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Sökning: WFRF:(Tahira Aneela)

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1.
  • Aftab, Umair, et al. (författare)
  • Mixed CoS2@Co3O4 composite material: An efficient nonprecious electrocatalyst for hydrogen evolution reaction
  • 2020
  • Ingår i: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 45:27, s. 13805-13813
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydrogen evolution reaction (HER) has been identified as a sustainable and environment friendly technology for a wide range of energy conversion and storage applications. The big barrier in realizing this green technology requires a highly efficient, earth-abundant, and low-cost electrocatalyst for HER. Various HER catalysts have been designed and reported, still, their performance is not up to the mark of Pt. Among them, cobalt-based, especially cobalt disulfide (CoS2) has shown significant HER activity and found suitable candidature for HER due to its low cost, simple to prepare, and exhibits good stability. Herein, we synthesized various nanostructured materials including pure CoS2, Co3O4 and their composites by wet chemical methods and found them active for HER. The scanning electron microscopy (SEM) has revealed a morphology of composite as a mixture of nanowires and round shape spherical nanoparticles with several microns in dimension. The X-ray diffraction (XRD) confirmed the cubic phase of CoS2 and cubic phase of Co3O4 in the composite materials. The chemical deposition of CoS2 onto Co3O4 has tailored the HER activity of CoS2@Co3O4 composite material. Two CoS2@Co3O4 composite materials were produced with varying amounts of Co3O4 and labeled as samples 1 and 2. The Co3O4 reduced the adsorption energy for hydrogen, decreased the aggregation of CoS2 and uplifted the stability of CoS2@Co3O4 a composite material in alkaline media. Sample 1 requires an overpotential of 320 mV to reach a current density of 10 mA/cm(2) and it exhibits a Tafel slope of 42 mVdec(-1) which is the key indicator for the fast HER kinetics on sample 1. The sample 1 is highly durable for 50 h and also it has excellent stability. The electrochemical impedance spectroscopy (EIS) revealed a small charge transfer resistance of 28.81 Ohms for the sample 1 with high capacitance double-layer value of 0.81 mF. EIS has supported polarization and Tafel slope results. Based on the partial physical characterization and the electrochemical results, the as-obtained sample 1 (CoS2@Co3O4 composite material) will find potential applications in an extended range of energy conversion and storage devices owing to its low cost, high abundance, and excellent efficiency. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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2.
  • Aftab, Umair, et al. (författare)
  • Nickel-cobalt bimetallic sulfide NiCo(2)S(4)nanostructures for a robust hydrogen evolution reaction in acidic media
  • 2020
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:37, s. 22196-22203
  • Tidskriftsartikel (refereegranskat)abstract
    • There are many challenges associated with the fabrication of efficient, inexpensive, durable and very stable nonprecious metal catalysts for the hydrogen evolution reaction (HER). In this study, we have designed a facile strategy by tailoring the concentration of precursors to successfully obtain nickel-cobalt bimetallic sulfide (NiCo2S4) using a simple hydrothermal method. The morphology of the newly prepared NiCo(2)S(4)comprised a mixture of microparticles and nanorods, which were few microns in dimension. The crystallinity of the composite sample was found to be excellent with a cubic phase. The sample that contained a higher amount of cobalt compared to nickel and produced single-phase NiCo(2)S(4)exhibited considerably improved HER performance. The variation in the salt precursor concentration during the synthesis of a material is a simple methodology to produce a scalable platinum-free catalyst for HER. The advantageous features of the multiple active sites of cobalt in the CN-21 sample as compared to that for pristine CoS and NiS laid the foundation for the provision of abundant active edges for HER. The composite sample produced a current density of 10 mA cm(-2)at an overpotential of 345 mV. Also, it exhibited a Tafel value of 60 mV dec(-1), which predominantly ensured rapid charge transfer kinetics during HER. CN-21 was highly durable and stable for 30 hours. Electrochemical impedance spectroscopy showed that the charge transfer resistance was 21.88 ohms, which further validated the HER polarization curves and Tafel results. CN-21 exhibited a double layer capacitance of 4.69 mu F cm(-2)and a significant electrochemically active surface area of 134.0 cm(2), which again supported the robust efficiency for HER. The obtained results reveal that our developed NiCo(2)S(4)catalyst has a high density of active edges, and it is a non-noble metal catalyst for the hydrogen evolution reaction. The present findings provide an alternative strategy and an active nonprecious material for the development of energy-related applications.
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3.
  • Aftab, Umair, et al. (författare)
  • The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
  • 2019
  • Ingår i: Catalysis Science & Technology. - : ROYAL SOC CHEMISTRY. - 2044-4753 .- 2044-4761. ; 9:22, s. 6274-6284
  • Tidskriftsartikel (refereegranskat)abstract
    • The fabrication of efficient, alkaline-stable and nonprecious electrocatalysts for the oxygen evolution reaction is highly needed; however, it is a challenging task. Herein, we report a noble metal-free advanced catalyst, i.e. the chemically reduced mixed transition metal oxide CuO-Co3O4 composite, with outstanding oxygen evolution reaction activity in alkaline media. Sodium borohydride (NaBH4) was used as a reducing agent for the mixed transition metal oxide CuO-Co3O4. The chemically reduced composite carried mixed valence states of Cu and Co, which played a dynamic role in driving an excellent oxygen evolution reaction process. The X-ray photo-electron spectroscopy (XPS) study confirmed high density of active sites in the treated sample with a large number of oxygen vacancies. The developed electrocatalyst showed the lowest overpotential of 144.5 mV vs. the reversible hydrogen electrode (RHE) to achieve the current density of 40 mA cm(-2) and remained stable for 40 hours throughout the chronoamperometry test at the constant potential of 1.39 V vs. RHE. Moreover, the chemically reduced composite was highly durable. Electrochemical impedance spectroscopy (EIS) confirmed the low charge transfer resistance of 13.53 ohms for the chemically reduced composite, which was 50 and 26 times smaller than that of Co3O4 and untreated CuO-Co3O4, respectively. The electrochemically active surface area for the chemically reduced composite was found to be greater than that for pristine CuO, Co3O4 and untreated pristine CuO-Co3O4. These findings reveal the possibility of a new gateway for the capitalization of a chemically reduced sample into diverse energy storage and conversion systems such as lithium-ion batteries and supercapacitors.
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4.
  • Aftab, Umair, et al. (författare)
  • Two step synthesis of TiO2–Co3O4 composite for efficient oxygen evolution reaction
  • 2021
  • Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 46:13, s. 9110-9122
  • Tidskriftsartikel (refereegranskat)abstract
    • For an active hydrogen gas generation through water dissociation, the sluggish oxygen evolution reaction (OER) kinetics due to large overpotential is a main hindrance. Herein, a simple approach is used to produce composite material based on TiO2/Co3O4 for efficient OER and overpotential is linearly reduced with increasing amount of TiO2. The scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) investigations reveal the wire like morphology of composite materials, formed by the self-assembly of nanoparticles. The titania nanoparticles were homogenously distributed on the larger Co3O4 nanoparticles. The powder x-ray diffraction revealed a tetragonal phase of TiO2 and the cubic phase of Co3O4 in the composite materials. Composite samples with increasing TiO2 content were obtained (18%, 33%, 41% and 65% wt.). Among the composites, cobalt oxide-titanium oxide with the highest TiO2 content (CT-20) possesses the lowest overpotential for OER with a Tafel slope of 60 mV dec−1 and an exchange current density of 2.98 × 10−3A/cm2. The CT-20 is highly durable for 45 h at different current densities of 10, 20 and 30 mA/cm2. Electrochemical impedance spectroscopy (EIS) confirmed the fast charge transport for the CT-20 sample, which potentially accelerated the OER kinetics. These results based on a two-step methodology for the synthesis of TiO2/Co3O4 material can be useful and interesting for various energy storage and energy conversion systems.
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5.
  • Ahmed Khand, Aftab, et al. (författare)
  • Synthesis of Sheet Like Nanostructures of NiO Using Potassium Dichromate as Surface Modifying Agent for the Sensitive and Selective Determination of Amlodipine Besylate (ADB) Drug
  • 2021
  • Ingår i: Electroanalysis. - : WILEY-V C H VERLAG GMBH. - 1040-0397 .- 1521-4109. ; 33:5, s. 1121-1128
  • Tidskriftsartikel (refereegranskat)abstract
    • The monitoring of hypertension drugs is very critical and important to sustain a healthy life. In this study, we have synthesized nickel oxide (NiO) nanostructures using potassium dichromate as surface modifying agent by hydrothermal method. These NiO nanostructures were found highly active for the oxidation of ADB besylate (ADB). The unit cell structure and morphology were investigated by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) techniques. The SEM study has confirmed the nano sheet like morphology and XRD analysis has described the cubic unit arrays of NiO. After the physical characterization, NiO nanostructures were used to modify the surface of glassy carbon electrode (GCE) by drop casting method. Then cyclic voltammetry (CV) was used to characterize the electrochemical activity of NiO nanostructures in the0.1 M phosphate buffer solution of pH 10.0 and a well resolved oxidation peak was identified at 0.70 V. The linear range for the NiO nanostructures was observed from 20-90 nM with a regression coefficient of 0.99 using CV. The calculated limit of detection (LOD) was 2.125 nM and the limit of quantification (LOQ) was 4.08 nM. Further to validate the CV calibration plot, an amperometry experiment was performed on the NiO nanostructures and sensors exhibited a linear range of 10 nM to 115 nM with LOD of 1.15 nM. The proposed approach was successfully used for the determination of ADB from commercial tablets and it reveals that the sensor could be capitalized to monitor ADB concentrations from pharmaceutical products. The use of potassium dichromate as a surface modifying agent for the metal oxide nanostructures may be of great interest to manipulate their crystal and surface properties for the extended range of biomedical and energy related applications.
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6.
  • Albaqami, Munirah D., et al. (författare)
  • The fast nucleation/growth of Co3O4 nanowires on cotton silk : the facile development of a potentiometric uric acid biosensor
  • 2022
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 12:29, s. 18321-18332
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we have used cotton silk as a source of abundant hydroxyl groups for the fast nucleation/growth of cobalt oxide (Co3O4) nanowires via a hydrothermal method. The crystal planes of the Co3O4 nanowires well matched the cubic phase. The as-synthesized Co3O4 nanowires mainly contained cobalt and oxygen elements and were found to be highly sensitive towards uric acid in 0.01 M phosphate buffer solution at pH 7.4. Importantly, the Co3O4 nanowires exhibited a large surface area, which was heavily utilized during the immobilization of the enzyme uricase via a physical adsorption method. The potentiometric response of the uricase-immobilizing Co3O4 nanowires was measured in the presence of uric acid (UA) against a silver/silver chloride (Ag/AgCl) reference electrode. The newly fabricated uric acid biosensor possessed a low limit of detection of 1.0 +/- 0.2 nM with a wide linear range of 5 nM to 10 mM and sensitivity of 30.6 mV dec(-1). Additionally, several related parameters of the developed uric acid biosensor were investigated, such as the repeatability, reproducibility, storage stability, selectivity, and dynamic response time, and these were found to be satisfactory. The good performance of the Co3O4 nanowires was verified based on the fast charge-transfer kinetics, as confirmed via electrochemical impedance spectroscopy. The successful practical use of the uric acid biosensor was demonstrated based on the recovery method. The observed performance of the uricase-immobilizing Co3O4 nanowires revealed that they could be considered as a promising and alternative tool for the detection of uric acid under both in vitro and in vivo conditions. Also, the use of cotton silk as a source of abundant hydroxyl groups may be considered for the remarkably fast nucleation/growth of other metal-oxide nanostructures, thereby facilitating the fabrication of functional electrochemical devices, such as batteries, water-splitting devices, and supercapacitors.
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7.
  • Ali Soomro, Razium, et al. (författare)
  • A highly selective and sensitive electrochemical determination of melamine based on succinic acid functionalized copper oxide nanostructures
  • 2015
  • Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 5:127, s. 105090-105097
  • Tidskriftsartikel (refereegranskat)abstract
    • This study presents the development of a highly selective and sensitive electrochemical sensor for the determination of melamine from aqueous environments. The sensor system is based on functionalised marigold-like CuO nanostructures fabricated using a controlled hydrothermal process, where the utilised succinic acid is considered to play a dual role as a functionalising and growth controlling agent (modifier). The fabricated nanostructures exhibit sharp and well-ordered structural features with dimensions (thickness) in the range of 10-50 nm. The sensor system exhibits strong linearity within the concentration range of 0.1 x 10(-9) to 5.6 x 10(-9) M and demonstrates an excellent limit of detection up to 0.1 x 10(-10) M. The extreme selectivity and sensing capability of the developed sensor is attributed to the synergy of selective interaction between succinic acid and melamine moieties, and the high surface area of marigold-like CuO nanostructures. In addition to this, the developed sensor was also utilised for the determination of melamine from real milk samples collected from different regions of Hyderabad, Pakistan. The obtained excellent recoveries proved the feasibility of the sensor for real life applications. The sensor system offers an operative measure for detecting extremely low melamine content with high selectivity in food contents.
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8.
  • Ali Soomro, Razium, et al. (författare)
  • Amino acid assisted growth of CuO nanostructures and their potential application in electrochemical sensing of organophosphate pesticide
  • 2016
  • Ingår i: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 190, s. 972-979
  • Tidskriftsartikel (refereegranskat)abstract
    • This work reports a highly sensitive electrochemical sensor for organophosphate pesticide (malathion) based on unique and attractive CuO nanostructures. The discussed nanostructures were synthesized using low temperature hydrothermal growth method utilizing green amino acids such as glycine, serine, threonine and histidine as effective bio-compatible templates. The morphological evaluation demonstrated formation of unique and attractive 1-D nanostructures reflecting the effective growth controlling and directing capabilities of the utilized amino acids. The as-synthesized CuO nanostructures were noted to possess high affinity towards malathion which enabled their application as electrode material for the development of affinity based electrochemical sensor. Although, the as-synthesized morphologies were all sensitive towards malathion but the glycine directed triangular flake-like nanostructures exhibited greater sensitivity compared to other competitors. The electrochemical behaviour of the modified electrodes was studied using cyclic voltammetry (CV) whereas, differential pulse voltammetry (DPV) was utilized for the analytical evaluation of the sensor. The developed sensor demonstrated high reproducibility, stability, wide detection window (1-12 nM), and sensitivity to detect malathion up to 0.1 nM based on suppressive signal measurement. In addition, the sensor system exhibited high anti-interference capability in the presence of common co-existing pesticides like lindane, carbendazim, and trichlorfon. The developed sensor provides an effective measure for detecting extremely low concentration of malathion with wide applicability in various fields. (C) 2015 Elsevier Ltd. All rights reserved.
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9.
  • Ali Soomro, Razium, et al. (författare)
  • Glutaric Acid Assisted Fabrication of CuO Nanostructures and their Application in Development of Highly Sensitive Electrochemical Sensor System for Carbamates
  • 2016
  • Ingår i: Electroanalysis. - : WILEY-V C H VERLAG GMBH. - 1040-0397 .- 1521-4109. ; 28:7, s. 1634-1640
  • Tidskriftsartikel (refereegranskat)abstract
    • This work describes the fabrication of unique arrow head shaped CuO nanostructures using simple hydrothermal treatment method. The highly attractive features were obtained by the application of glutaric acid utilised simultaneous as template and functionalising agent. The functionalised nanostructures were known to possess excellent potential towards the electro-catalytic oxidation of carbofuran pesticide. The generated intense electrochemical signal with lower potential value enabled sensitive and selective determination of carbofuran up to 1 x 10(-3) mu M with wide sensing window in range of 0.01 to 0.16 mu M. The feasibility of the developed sensor system for the practical application was also studied by testing its potential in real sample extracts of various vegetables. The excellent recoveries demonstrated the analytical robustness of the developed sensor system. The sensor system utilises a new and simple approach towards sensitive determination of toxic pesticides reflecting its wide spectrum application in various fields.
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10.
  • Alshgari, Razan A., et al. (författare)
  • Manipulation of CuO morphology for efficient potentiometric detection of urea via slow nucleation/growth kinetics exerted by mixed solvents
  • 2022
  • Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 33, s. 25250-25262
  • Tidskriftsartikel (refereegranskat)abstract
    • Controlling the reaction kinetics during the nucleation/growth of cupric oxide (CuO) nanostructures is very critical in order to achieve a specific and well-defined morphology. For this purpose, we have slowed down the reaction speed using a mixed solvent concept and successfully obtained a chain-like morphology of CuO nanostructures using hydrothermal method. The CuO chain-like morphology was synthesized using a 1:1 (v/v) ratio of ethylene glycol and water. The morphology and crystalline features of CuO were studied by scanning electron microscopy (SEM) and powder X-ray diffraction techniques. The high resolution transmission electron microscopy revealed 5 nm crystallite size for the CuO material prepared in the mixed solvents. The obtained results have shown that the prepared CuO chains had a monocline phase, containing only Cu and O as main elements as confirmed by energy dispersive spectroscopy. This unique morphology obtained from mixed solvent process has provided a better surface for the loading of urease enzyme, thus it enabled the development of sensitive and selective urea biosensor in phosphate buffer solution of pH 7.4. The physical adsorption method was used to immobilize urease enzyme onto the nano surface of CuO. The fabricated biosensor based on urease/CuO chains has shown a dynamic linear range from 0.0005 to15 mM with a low limit of detection 0.0001 mM. Additionally, a fast response time aroudn1s, h high selectivity, stability, repeatability, storage time, and reproducibility were observed. The effect of pH and temperature on the potentiometric signal of the developed biosensor was also examined. Importantly, the practical aspects of the fabricated urea biosensor were probed and the obtained percent recovery results revealed an outstanding performance. The strategy of using mixed solvent with equal volume ratio would be useful for the preparation of other metal oxides with improved catalytic properties for a wide range of clinical, biomedical and other related applications.
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11.
  • Amin, Sidra, et al. (författare)
  • A practical non-enzymatic urea sensor based on NiCo 2 O 4 nanoneedles
  • 2019
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo 2 O 4 ) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo 2 O 4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo 2 O 4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo 2 O 4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co 3 O 4 . The GCE-modified electrode is highly sensitive towards urea, with a linear response (R 2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
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12.
  • Amin, Sidra, et al. (författare)
  • A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles
  • 2019
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 mu M) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R-2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 mu M. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
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13.
  • Amin, Sidra, et al. (författare)
  • A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles
  • 2019
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:25, s. 14443-14451
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R2 = 0.99) over the concentration range 0.01–5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.
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14.
  • Amin, Sidra, et al. (författare)
  • A sensitive enzyme-free lactic acid sensor based on NiO nanoparticles for practical applications
  • 2019
  • Ingår i: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 11, s. 3578-3583
  • Tidskriftsartikel (refereegranskat)abstract
    • A facile and efficient electrochemical sensing platform has been successfully exploited for the first time for the determination of lactic acid using a nickel oxide (NiO) nanoparticle-modified glassy carbon electrode (GCE). Nickel oxide nanoparticles were prepared by a chemical growth method using different quantities of arginine as a soft template. The structural and morphological properties of NiO nanoparticles were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cyclic voltammetry (CV) was used to study the electrochemical properties of various samples. The modified electrode is highly sensitive and presents a linear response over a wide range (0.005–5 mM) of lactic acid concentrations in 0.1 M NaOH. The detection limit for the sensor was found to be 5.7 μM, and it exhibits good stability. Furthermore, the sensor shows excellent selectivity in the presence of common interfering species. The lactic acid sensor showed good viability for lactic acid analysis in real samples (milk, yogurt and red wine) and demonstrated significant advancement in sensor technology for practical applications.
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15.
  • Amin, Sidra, et al. (författare)
  • Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media
  • 2020
  • Ingår i: Electroanalysis. - : John Wiley & Sons. - 1040-0397 .- 1521-4109. ; 32:5, s. 1052-1059
  • Tidskriftsartikel (refereegranskat)abstract
    • Nickel oxide (NiO) nanostructures are employed in the basic medium for the oxidation of ethanol. A variety of NiO nanostructures are synthesized by wet chemical growth method, using different hydroxide (OH−) ion sources, particularly from ammonia, hexamethylenetetramine, urea and sodium hydroxide. The use of urea as (OH−) ion source results in flower‐like NiO structures composed by extremely thin nanowalls (thickness lower than 10 nm,), which demonstrated to be the most active for ethanol oxidation. All the samples exhibit NiO cubic phase, and no other impurity was detected. The cyclic voltammetry (CV) curves of NiO nanostructures were found linear over the concentration range 0.1–3.5 mM (R2=0.99) of ethanol, with the limit of detection estimated to be 0.013 mM for ethanol. The NiO nanostructures exhibit a selective signal towards ethanol oxidation in the presence of different members of alcohol family. The proposed NiO nanostructures showed a significant practicality for the reproducible and sensitive determination of ethanol from brandy, whisky, mixture of brandy and rum, and vodka samples. The nanomaterial was used as a surface modifying agent for the glassy carbon electrode and it showed a stable electro‐oxidation activity for the ethanol for 16 days. These findings indicate that the presented NiO nanomaterial can be applied in place of noble metals for ethanol sensing and other environmental applications (like fuel cells).
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16.
  • Amin, Sidra, et al. (författare)
  • MoSx-Co3O4 Nanocomposite for Selective Determination of Ascorbic Acid
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2595-2603
  • Tidskriftsartikel (refereegranskat)abstract
    • Designing a nanocomposite with sensitive and selective determination of ascorbic acid is challenging task. It is possible through the exploitation of attractive features of nanoscience and nanotechnology for the synthesis of nanostructured materials. Herein, we report the decoration of nanoparticle of MoSx on the surface of Co3O4 nanowires by hydrothermal method. The MoSx nanoparticles shared the large surface on the Co3O4 nanowires, thus it supported in the development enzyme free ascorbic acid sensor. Non-enzymatic sensor based on MoSx-Co3O4 composite was found very selective for the determination of ascorbic acid (AA) in phosphate buffer solution of pH 7.4. The MoSx-Co3O4 nanocomposite was used to modify the glassy carbon electrode to measure AA from variety of practical samples. The MoSx-Co3O4 nanocomposite was used to modify the glassy carbon electrode and it has shown the attractive analytical features such as a low working potential +0.3 V, linear range of concentration from 100-7000 mu M, low limit of detection 14 mu M, and low limit of quantification (LOQ) of 42 mu M. The developed sensor is highly selective and stable. Importantly, it was applied successfully for the practical applications such as detection of AA from grapefruit, tomato and lemon juice. The excellent electrochemical properties of fabricated MoSx-Co3O4 nanocomposite can be attributed to the increasing electro active surface area of MoSx. The presented nanocomposite is earth abundant, environment friendly and inexpensive and it holds promising features for the selective and sensitive determination of AA from practical applications. The nanocomposite can be capitalized into the wide range of biomedical applications.
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17.
  • Baloach, Qurrat-ul-Ain, et al. (författare)
  • A Robust, Enzyme-Free Glucose Sensor Based on Lysine-Assisted CuO Nanostructures
  • 2016
  • Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 16:11
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of a nanomaterial with enhanced and desirable electrocatalytic properties is of prime importance, and the commercialization of devices containing these materials is a challenging task. In this study, unique cupric oxide (CuO) nanostructures were synthesized using lysine as a soft template for the evolution of morphology via a rapid and boiled hydrothermal method. The morphology and structure of the synthesized CuO nanomaterial were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The prepared CuO nanostructures showed high potential for use in the electrocatalytic oxidation of glucose in an alkaline medium. The proposed enzyme-free glucose sensor demonstrated a robust response to glucose with a wide linear range and high sensitivity, selectivity, stability, and reproducibility. To explore its practical feasibility, the glucose content of serum samples was successfully determined using the enzyme-free sensor. An analytical recovery method was used to measure the actual glucose from the serum samples, and the results were satisfactory. Moreover, the presented glucose sensor has high chemical stability and can be reused for repetitive measurements. This study introduces an enzyme-free glucose sensor as an alternative tool for clinical glucose quantification.
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18.
  • Baloach, Qurrat-ul-ain, et al. (författare)
  • An amperometric sensitive dopamine biosensor based on novel copper oxide nanostructures
  • 2017
  • Ingår i: Microsystem Technologies. - : SPRINGER. - 0946-7076 .- 1432-1858. ; 23:5, s. 1229-1235
  • Tidskriftsartikel (refereegranskat)abstract
    • It is highly important to explore the influence of counter anions on the morphology in order to have a desired nanostructure with unique properties. Therefore, in this research work the influence of counter anions on the morphology of copper oxide (CuO) nanostructures is presented using copper chloride and copper acetate salts. A significant role of counter anions on the morphology of CuO nanostructures is observed. The hydrothermal method is used to carry out the synthesis of CuO nanomaterial. The prepared CuO nanostructures are characterized by scanning electron microscopy and X-ray diffraction techniques. The prepared CuO nanomaterial exhibits porous nature with thin nanowires and sponge like morphologies. The dopamine sensing application was carried for exploring the electrocatalytic properties of CuO nanostructures. The presented dopamine biosensor exhibited wide linear range for detection of dopamine from 5 to 40 A mu M with sensitivity of 12.8 A mu A mM(-1) cm(-2). The limit of detection and limit of quantification were estimated in order 0.11 and 0.38 A mu M respectively. The developed dopamine biosensor is highly sensitive, selective, stable and reproducible. The common interfering species such as glucose, ascorbic acid and uric acid showed negligible change in the current when same concentration of dopamine and these interfering species was used. The fabricated biosensor could be used for the determination of dopamine from real blood samples.
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19.
  • Bhatti, Adeel Liaquat, et al. (författare)
  • An Efficient and Functional Fe3O4/Co3O4 Composite for Oxygen Evolution Reaction
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2675-2680
  • Tidskriftsartikel (refereegranskat)abstract
    • The design of efficient, stable, durable and noble metal free electro catalysts for oxygen evolution reaction (OER) are of immediate need, but very challenging task. In this study, iron induction into cobalt oxide (Co3O4) has resulted composite structure by wet chemical method. The iron impurity has brought an electronic disorder into Fe3O4/cobalt oxide composite thereby efficient oxygen evolution reaction is demonstrated. An addition of iron content into composite resulted the alternation of morphology from Nano rods to clusters of nanoparticles. The successive addition of iron into composite system reduced the onset potential of OER as compared to the pristine cobalt oxide. A Tafel slope of 80 mVdec(-1) indicates the favorable oxygen evolution reaction kinetics on the sample 4. An over-potential of 370 mV is required to reach a 10 mAcm(-2) current density which is acceptable for a nonprecious catalyst. The catalyst is highly durable and stable for 30 hours. Electrochemical impedance spectroscopy further provided a deeper insight on charge transfer resistance and sample 4 has low charge transfer resistance that supported the OER polarization curves. The sample 4 has more electrochemical active surface area of 393.5 cm(2). These obtained results are exciting and highlighting the importance of composite structure and leave a huge space for the future investigations on composite materials for energy related applications.
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20.
  • Bhatti, Adeel Liaquat, et al. (författare)
  • Facile doping of nickel into Co3O4 nanostructures to make them efficient for catalyzing the oxygen evolution reaction
  • 2020
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:22, s. 12962-12969
  • Tidskriftsartikel (refereegranskat)abstract
    • Designing a facile and low-cost methodology to fabricate earth-abundant catalysts is very much needed for a wide range of applications. Herein, a simple and straightforward approach was developed to tune the electronic properties of cobalt oxide nanostructures by doping them with nickel and then using them to catalyze the oxygen evolution reaction (OER) in an aqueous solution of 1.0 M KOH. The addition of a nickel impurity improved the conductivity of the cobalt oxide, and further increased its activity towards the OER. Analytical techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and powder X-ray diffraction (XRD) were used to investigate, respectively, the morphology, composition and crystalline structure of the materials used. The nickel-doped cobalt oxide material showed randomly oriented nanowires and a high density of nanoparticles, exhibited the cubic phase, and contained cobalt, nickel and oxygen as its main elements. The nickel-doped cobalt oxide also yielded a Tafel slope of 82 mV dec(-1) and required an overpotential of 300 mV to reach a current density of 10 mA cm(-2). As an OER catalyst, it was shown to be durable for 40 h. Electrochemical impedance spectroscopy (EIS) analysis showed a low charge-transfer resistance of 177.5 ohms for the nickel-doped cobalt oxide, which provided a further example of its excellent OER performance. These results taken together indicated that nickel doping of cobalt oxide can be accomplished via a facile approach and that the product of this doping can be used for energy and environmental applications.
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21.
  • Bhatti, Adeel Liaquat, et al. (författare)
  • Nanostructured Co3O4 electrocatalyst for OER : The role of organic polyelectrolytes as soft templates
  • 2021
  • Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 398
  • Tidskriftsartikel (refereegranskat)abstract
    • Designing an efficient electrocatalyst for the oxygen evolution reaction (OER) in alkaline media is highly needed but very challenging task. Herein, we used organic polyelectrolytes such as (carboxymethyl cellulose) CMC and polyacrylamide polymers for the growth of Co3O4 nanostructures by aqueous chemical growth method. The morphology and composition studies were performed on scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) techniques. The structural properties and the surface chemistry of the Co3O4 electrocatalysts were correlated to the OER performance, and the enhancement mechanism with respect to pristine Co3O4 was observed to be specifically related to the polyelectrolyte templating role.Co3O4@CMC composites displayed reduced crystallite size, producing OER overpotential as low as 290 mV at 10 mAcm−2 in 1.0 KOH and Tafel slope of 71 mVdec−1, suggesting fast transfer of intermediates and electrons during water electrolysis. On the other hand, the use of polyacrylamide and its different templating mechanism resulted in similar crystallite size, but preferential exposed faces and larger surface vacancies content, as demonstrated by HR-TEM and XPS, respectively. Consistently, this material displays cutting-edge OER performance, such as overpotential of 260 mV at 10 mAcm−2 and a low Tafel slope of 63 mVdec−1. The proposed strategy for the preparation of Co3O4 nanostructures in the presence of CMC and polyacrylamide is facile, mass production, thus it could equally contributed towards the realization of hydrogen energy. Therefore, these nanostructures of Co3O4 can be regarded as an alternative and promising materials for the different electrochemical applications including fuel cells, metal air batteries, overall water electrolysis and other energy storage devices.
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22.
  • Bhatti, Muhammad Ali, et al. (författare)
  • Efficient photo catalysts based on silver doped ZnO nanorods for the photo degradation of methyl orange
  • 2019
  • Ingår i: Ceramics International. - Oxford : Elsevier. - 0272-8842 .- 1873-3956. ; 45:17, Part B, s. 23289-23297
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, the doped ZnO nanorods with silver (Ag) as photosensitive material are prepared by the solvothermal method. The structural and optical characterization is carried out by the scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and UV–visible spectroscopy. The use of Ag as dopant did not alter the morphology of ZnO except sample 4 which has flower like morphology. The Ag, Zn and O are the main constituent of doped materials. The XRD revealed a hexagonal phase for ZnO and cubic phase for silver and confirmed the successful doping of Ag. The photocatalytic activity of Ag doped ZnO nanorods was investigated for the photo degradation of methyl orange. The photocatalytic measurements show that 88% degradation of methyl orange by the sample 4 within the 2 h of UV light treatment (365 nm) is significant advancement in the photocatalyst and provide the inexpensive and promising materials for the photochemical applications. © 2019 Elsevier Ltd and Techna Group S.r.l.
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23.
  • Bhatti, Muhammad Ali, et al. (författare)
  • Enzymes and phytochemicals from neem extract robustly tuned the photocatalytic activity of ZnO for the degradation of malachite green (MG) in aqueous media
  • 2021
  • Ingår i: Research on chemical intermediates (Print). - : SPRINGER. - 0922-6168 .- 1568-5675. ; 47:4, s. 1581-1599
  • Tidskriftsartikel (refereegranskat)abstract
    • The malachite green (MG) is very difficult to degrade in water; thus, it needs an efficient photocatalyst. In this study, neem extract was used to tune the surface and crystal properties of ZnO nanostructures for the photodegradation of MG. The biosynthesized ZnO samples were prepared by hydrothermal method in the presence of 5, 10 and 15 mL of neem extract. The structural characterization has shown nanoparticle like morphology of ZnO as revealed by scanning electron microscopy (SEM) and hexagonal phase was confirmed by powder X-ray diffraction (XRD) technique. The XRD analysis has shown a shift in the 2 theta towards lower angle for ZnO with increasing amount of neem extract. Also, the crystallite particle size of ZnO was decreased with increasing neem extract. The UV-visible spectroscopy has shown the decrease in the optical band gap of ZnO, and the lowest band gap is possessed by ZnO sample produced with 15 mL of neem extract. The ZnO sample obtained with 15 mL of neem extract has shown approximately 99% degradation efficiency for MG for 70 min in aqueous solution. The superior photocatalytic activity of ZnO sample with 15 mL of neem extract could be attributed from the decrease in charge recombination rate due to the decreased optical band gap and particle size.
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24.
  • Bhatti, Muhammad Ali, et al. (författare)
  • Low Temperature Aqueous Chemical Growth Method for the Doping of W into ZnO Nanostructures and Their Photocatalytic Role in the Degradration of Methylene Blue
  • 2022
  • Ingår i: Journal of cluster science. - : SPRINGER/PLENUM PUBLISHERS. - 1040-7278 .- 1572-8862. ; 33:4, s. 1445-1456
  • Tidskriftsartikel (refereegranskat)abstract
    • In this research work, we have produced tungsten (W) doped ZnO nanostructures via low-temperature aqueous chemical growth method. The morphology, crystal arrays and composition was investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and energy dispersive X-rays (EDX) respectively. The SEM results indicate the nanowire morphology before and after the doping of W into ZnO and XRD study has shown the hexagonal crystallography of W doped ZnO samples. The EDX study has confirmed the successful doping of W into ZnO crystal lattices. The photodegradation performance of methylene blue was evaluated with W doped ZnO samples and pristine ZnO in aqueous solution. The measured degradation efficiencies for the different W doped ZnO samples were 5 wt%, 10 wt%, 15 wt% and 20 wt% at pH 5 are 87.8%, 92.3%, 92.8% and 96.9%), at pH 9 (72.1%, 90.7%, 92.1%, and 96.4%) and at pH 11 (80%, 85%, 87% and 89%) for the time interval of 90 min respectively. The pH of dye solution has significant effect on the degradation efficiency. These findings show that the W doped ZnO samples have superior degradation efficiency of 96.6% in a very short interval of time. The swift degradation kinetics for the W doped ZnO samples is attributed to the reduction in the energy band gap, decrease in particle size, enhanced surface area, decrease in the recombination rate and foster charge separation process. The obtained results are exciting and providing efficient earth-abundant photocatalysts for the energy and environmental purposes.Kindly confirm the Given names and Family names for all the authors.They are correct.
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25.
  • Bhatti, Muhammad Ali, et al. (författare)
  • TiO2/ZnO Nanocomposite Material for Efficient Degradation of Methylene Blue
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2511-2519
  • Tidskriftsartikel (refereegranskat)abstract
    • In this research work, we have produced a composite material consisting titanium dioxide (TiO2) and zinc oxide (ZnO) nanostructures via precipitation method. Scanning electron microscopy (SEM) study has shown the mixture of nanostructures consisting nanorods and nano flower. Energy dispersive spectroscopy (EDS) study has confirmed the presence of Ti, Zn and O as main elements in the composite. X-ray diffraction (XID) study has revealed that the successful presence of TiO2 and ZnO in the composite. The composite material exhibits small optical energy band gap which led to reduction of the charge recombination rate of electron-hole pairs. The band gap for the composite TiO2/ZnO samples namely 1, 2, 3 and 4 is 3.18, 3.00, 2.97 and 2.83 eV respectively. Small optical bandgap gives less relaxation time for the recombination of electron and hole pairs, thus favorable photodegradation is found. The degradation efficiency for the TiO2/ZnO samples for methylene blue in order of 55.03%, 75.7%, 85.14% and 90.08% is found for the samples 1, 2, 3 and 4 respectively. The proposed study of titanium dioxide addition into ZnO is facile and inexpensive for the development of efficient photocatalysts. This can be capitalized at large scale for the energy and environmental applications.
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26.
  • Chang, Abdul Sattar, et al. (författare)
  • Pd-Co3O4-based nanostructures for the development of enzyme-free glucose sensor
  • 2022
  • Ingår i: Bulletin of Materials Science. - : INDIAN ACAD SCIENCES. - 0250-4707 .- 0973-7669. ; 45:2
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we report enzyme-free glucose sensors based on palladium (Pd) nanoparticles deposited onto Co3O4 nanostructures. A simple, low-temperature aqueous method was used for the fabrication of Co3O4 nanostructures. Then, Pd nanoparticles were decorated onto Co3O4 nanostructures using the ultraviolet reduction method. Morphology, elemental composition and crystalline features of the proposed composite nanostructures were investigated by powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. Cyclic voltammetry and linear sweep voltammetry were used to investigate the electrochemical behaviour of Pd-Co3O4 nanostructures during glucose sensing. The proposed nanostructures showed excellent electrochemical activity for the quantitative detection of glucose at a potential of 0.6 V vs. Ag/AgCl. Importantly, the fabricated enzyme-free glucose sensor shows a linear response over the range of 1-6.0 mM glucose, with a limit of detection of 0.01 mM. The interference study was also carried out to probe the selectivity of Pd-Co3O4 nanostructures towards glucose detection in the presence of different interfering substances. The combined results attest that the as-synthesized Pd-Co3O4 nanostructures are highly stable and selective for the detection of glucose, suggesting their great potential for the quantitative determination of glucose in different biological fluids.
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27.
  • Gulzar, Ali, et al. (författare)
  • Functional CuO Microstructures for Glucose Sensing
  • 2018
  • Ingår i: Journal of Electronic Materials. - : Springer. - 0361-5235 .- 1543-186X. ; 47:2, s. 1519-1525
  • Tidskriftsartikel (refereegranskat)abstract
    • CuO microstructures are produced in the presence of water-soluble amino acids by hydrothermal method. The used amino acids include isoleucine, alpha alanine, and arginine as a soft template and are used for tuning the morphology of CuO nanostructures. The crystalline and morphological investigations were carried out by x-ray diffraction (XRD) and scanning electron microscopy techniques. The XRD study has shown that CuO material obtained in the presence of different amino acids is of high purity and all have the same crystal phase. The CuO microstructures prepared in the presence of arginine were used for the development of sensitive and selective glucose biosensor. The linear range for the glucose detection are from 0.001 mM to 30 mM and limit of detection was found to be 0.0005 mM. The sensitivity was estimated around 77 mV/decade. The developed biosensor is highly selective, sensitive, stable and reproducible. The glucose biosensor was used for the determination of real human blood samples and the obtained results are satisfactory. The CuO material is functional therefore can be capitalized in wide range of applications such as lithium ion batteries, all oxide solar cells and supercapacitors.
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28.
  • Hanan, Abdul, et al. (författare)
  • PdO@CoSe2 composites: efficient electrocatalysts for water oxidation in alkaline media
  • 2022
  • Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 13:1, s. 743-755
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we have prepared cobalt selenide (CoSe2) due to its useful aspects from a catalysis point of view such as abundant active sites from Se edges, and significant stability in alkaline conditions. CoSe2, however, has yet to prove its functionality, so we doped palladium oxide (PdO) onto CoSe2 nanostructures using ultraviolet (UV) light, resulting in an efficient and stable water oxidation composite. The crystal arrays, morphology, and chemical composition of the surface were studied using a variety of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It was also demonstrated that the composite systems were heterogeneous in their morphology, undergoing a shift in their diffraction patterns, suffering from a variety of metal oxidation states and surface defects. The water oxidation was verified by a low overpotential of 260 mV at a current density of 20 mA cm(-2) with a Tafel Slope value of 57 mV dec(-1). The presence of multi metal oxidation states, rich surface edges of Se and favorable charge transport played a leading role towards water oxidation with a low energy demand. Furthermore, 48 h of durability is associated with the composite system. With the use of PdO and CoSe2, new, low efficiency, simple electrocatalysts for water catalysis have been developed, enabling the development of practical energy conversion and storage systems. This is an excellent alternative approach for fostering growth in the field.
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29.
  • Hussain Ibupoto, Zafar, et al. (författare)
  • The Synthesis of Functional Cobalt Oxide Nanostructures, and their Sensitive Glucose Sensing Application
  • 2017
  • Ingår i: Electroanalysis. - : WILEY-V C H VERLAG GMBH. - 1040-0397 .- 1521-4109. ; 29:1, s. 213-222
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, a novel approach is adapted for the synthesis of new nanostructures of cobalt oxide (Co3O4) by low temperature aqueous chemical growth method in the presence of water soluble amino acids such as L-arginine, L-aspartic acid, L-isoleucine, L-leucine, Lserine and L-threonine. The synthesized nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The nanostructures exhibit well defined morphology and are of high purity. To explore the potential application of the prepared nanostructures of cobalt oxide, the non-enzymatic glucose sensor is developed by modifying the glassy carbon electrode. Serine assisted cobalt oxide nanostructures showed excellent sensitivity of 4169.00 mu A/mMcm(2), wide linear range of 0.01 mM to 20 mM and detection limit was estimated as 0.001 mM (S/N= 3). The analytical parameters for the serine assisted cobalt oxide nanostructures based glucose sensor were evaluated and it was found that the sensor is highly selective, reproducible, repeatable, reversible, and stable. Finally, the practical application of the serine assisted cobalt oxide nanostructures based glucose sensor was examined by measuring the glucose concentrations from real human blood samples.
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30.
  • Ibupoto, Zafar Hussain, et al. (författare)
  • Synthesis of Heart/Dumbbell-Like CuO Functional Nanostructures for the Development of Uric Acid Biosensor
  • 2018
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 11:8
  • Tidskriftsartikel (refereegranskat)abstract
    • It is always demanded to prepare a nanostructured material with prominent functional properties for the development of a new generation of devices. This study is focused on the synthesis of heart/dumbbell-like CuO nanostructures using a low-temperature aqueous chemical growth method with vitamin B-12 as a soft template and growth directing agent. CuO nanostructures are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. CuO nanostructures are heart/dumbbell like in shape, exhibit high crystalline quality as demonstrated by XRD, and have no impurity as confirmed by XPS. Apparently, CuO material seems to be porous in structure, which can easily carry large amount of enzyme molecules, thus enhanced performance is shown for the determination of uric acid. The working linear range of the biosensor is 0.001 mM to 10 mM with a detection limit of 0.0005 mM and a sensitivity of 61.88 mV/decade. The presented uric acid biosensor is highly stable, repeatable, and reproducible. The analytical practicality of the proposed uric acid biosensor is also monitored. The fabrication methodology is inexpensive, simple, and scalable, which ensures the capitalization of the developed uric acid biosensor for commercialization. Also, CuO material can be used for various applications such as solar cells, lithium ion batteries, and supercapacitors.
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31.
  • Ibupoto, Zafar, et al. (författare)
  • MoSx@NiO Composite Nanostructures : An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media
  • 2019
  • Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 29:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The design of the earth‐abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge‐like morphology and are completely covered by the sheet‐like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm−2 current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2‐based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost‐effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.
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32.
  • Izyumskaya, N., et al. (författare)
  • Review-Electrochemical Biosensors Based on ZnO Nanostructures
  • 2017
  • Ingår i: ECS Journal of Solid State Science and Technology. - : Electrochemical Society. - 2162-8769 .- 2162-8777. ; 6:8, s. Q84-Q100
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent years, electrochemical biosensors based on semiconductor and metal nanostructures have attracted a great deal of attention as new instruments in the healthcare arsenal that could substantially enhance early diagnostics capabilities and thus enable active health management. Among numerous materials studied, nanostructured ZnO has been recognized as a promising platform for biomedical applications owing to its low cost, relative ease of preparation leading to a rich variety of nanostructures with high aspect ratios (nanowires, nanobelts, nanoflakes), proven biocompatibility in the bulk form, electronic properties supporting various device types, and catalytic surface activity. In this contribution, we review the recent progress in development of enzymatic and non-enzymatic biosensors based on ZnO nanostructures. After a critical discussion of biocompatibility of nanostructured ZnO, we segue into the discussion of ZnO-based devices for detection of physiologically important analytes, including glucose, cholesterol, L-lactic acid, uric acid, metal ions, and pH. Special attention is given to ZnO nanorod based sensors for intracellular measurements.
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33.
  • Khokhar, Shams Parveen, et al. (författare)
  • An Efficient Nickel Sulfide@NiO Nanocomposite Catalyst with High Density of Active Sites for the Hydrogen Evolution Reaction in Alkaline Media
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2520-2528
  • Tidskriftsartikel (refereegranskat)abstract
    • Efficient hydrogen evolution reaction (HER) catalysts based on the earth-abundant materials are highly vital to design practical and environmentally friendly water splitting devices. In this study, we present an optimized strategy for the development of active catalysts for hydrogen evolution reaction HER. The composite catalysts are prepared with the nanosurface of NiO for the deposition of NiS by hydrothermal method. In alkaline electrolyte, the NIS/NiO nanocomposite has shown excellent catalytic HER properties at the low onset potential and small Tafel slope of 72 mV dec(-1). A current density of 10 mA/cm(2) is achieved by the nanocomposite obtained with 0.4 gram of NiO as nanosurface for the deposition of NiS (sample 4) at the cost of 429 mV versus RHE. The sample 4 carries more active sites that allow it to act as excellent HER catalyst. Based on this study, we conclude that increasing the nickel oxide content into composite sample facilitates the HER process. Additionally, a long term HER stability for 10 hours and good durability is also demonstrated by the sample 4. Our findings reveal that the optimization of nickel oxide content in the preparation of catalyst leads to the excellent HER activity for the design of practical water splitting devices and other related applications.
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34.
  • Kumar, Raj, et al. (författare)
  • Synthesis of Sheet Like Morphology of NiO for Sensitive and Selective Determination of Urea
  • 2017
  • Ingår i: Sensor Letters. - : American Scientific Publishers. - 1546-198X .- 1546-1971. ; 15:10, s. 803-810
  • Tidskriftsartikel (refereegranskat)abstract
    • An efficient and simple method has been demonstrated for the synthesis of nickel oxide nanostructures using urea as a capping agent. The nanosheet-like morphology was confirmed by scanning electron microscopy, crystalline nature was studied by using the X-ray diffraction (XRD) and surface area of nanomaterial was investigated by automated sorption analyzer. Then synthesized NiO nanostructures were used to fabricate the surface of glassy carbon electrode (GCE). The electrocatalytic parameters of modified NiO/GCE electrode were investigated by using various techniques such as electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV), differential pulse voltammetry (DPV), normal pulse voltammetry (NPV) and cyclic voltammetry (CV) and chronoamperometry. Various working experimental conditions were optimized in order to attain the highest sensitivity for the determination of urea and the highest peak current 1032 μA of response were obtained at 100 μM concentration of urea. A linear calibration plot was obtained for peak current versus concentration of urea in the range of 10 μM urea to 80 μM urea with a good detection limit of 2 μM. The proposed working strategy was successfully employed for the estimation of urea in human urine samples and the obtained results are found satisfactory. The newly functional urea sensor can be exploited at large scale as an alternative analytical device beside to the other reported urea sensors
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35.
  •  
36.
  • Kumar, Shusheel, et al. (författare)
  • Transforming NiCo2O4 nanorods into nanoparticles using citrus lemon juice enhancing electrochemical properties for asymmetric supercapacitor and water oxidation
  • 2023
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 13:27, s. 18614-18626
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, the nanostructured nickel–cobalt bimetallic oxide (NiCo2O4) material with high electrochemical activity has received intensive attention. Beside this, the biomass assisted synthesis of NiCo2O4 is gaining popularity due to its advantageous features such as being low cost, simplicity, minimal use of toxic chemicals, and environment-friendly and ecofriendly nature. The electrochemical activity of spinel NiCo2O4 is associated with its mixed metal oxidation states. Therefore, much attention has been paid to the crystal quality, morphology and tunable surface chemistry of NiCo2O4 nanostructures. In this study, we have used citrus lemon juice consisting of a variety of chemical compounds having the properties of a stabilizing agent, capping agent and chelating agent. Moreover, the presence of several acidic chemical compounds in citrus lemon juice changed the pH of the growth solution and consequently we observed surface modified and structural changes that were found to be very effective for the development of energy conversion and energy storage systems. These naturally occurring compounds in citrus lemon juice played a dynamic role in transforming the nanorod morphology of NiCo2O4 into small and well-packed nanoparticles. Hence, the prepared NiCo2O4 nanostructures exhibited a new surface-oriented nanoparticle morphology, high concentration of defects on the surface (especially oxygen vacancies), sufficient ionic diffusion and reaction of electrolytic ions, enhanced electrical conductivity, and favorable reaction kinetics at the interface. The electrocatalytic properties of the NiCo2O4 nanostructures were studied in oxygen evolution reaction (OER) at a low overpotential of 250 mV for 10 mA cm−2, Tafel slope of 98 mV dec−1, and durability of 40 h. Moreover, an asymmetric supercapacitor was produced and the obtained results indicated a high specific capacitance of (Cs) of 1519.19 F g−1, and energy density of 33.08 W h kg−1 at 0.8 A g−1. The enhanced electrochemical performance could be attributed to the favorable structural changes, surface modification, and surface crystal facet exposure due to the use of citrus lemon juice. The proposed method of transformation of nanorod to nanoparticles could be used for the design of a new generation of efficient electrocatalyst materials for energy storage and conversion uses.
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37.
  • Lal, Ramesh, et al. (författare)
  • Chemically Coupled Multiwall Carbon Nanotubes with Leaf-Like Nanostructures of NiO for Sensitive and Selective Determination of Uric Acid
  • 2021
  • Ingår i: Journal of Electronic Materials. - : SPRINGER. - 0361-5235 .- 1543-186X. ; 50:5, s. 2852-2859
  • Tidskriftsartikel (refereegranskat)abstract
    • The chemical coupling of NiO nanostructures with thermally treated multiwall carbon nanotubes (MWCNTs) is not reported as it provides an enhanced dispersion of composite material in water. The dispersion of MWCNTs has been considered a big challenge. For this purpose, we first thermally treated MWCNTs at 1000 degrees C in air for 30 min. Then, thermally treated MWCNTs were chemically coupled with NiO nanostructures by a hydrothermal method. The material characterization in terms of structure, morphology, and composition is well studied by different analytical techniques. The NiO composite (sample 2) with highest weight of MWCNTs had a leaf-like morphology and it exhibits a cubic phase of NiO. Cyclic voltammetry (CV) was used to study the electrochemical activity of prepared composite material towards the oxidation of uric acid in the phosphate buffer solution of pH 7.0. Sample 2 showed a well-behaved anodic peak with enhanced peak current and exhibited a linear range from 0.01 mM to 2.5 mM for uric acid with a low limit of detection 0.001mM. Sample 2 was found to be very selective under the environment of competing interferents such as urea, glucose, lactic acid and ethanol. This sample exhibits significant stability, thus it is a potential protocol for the monitoring of uric acid from real samples. This study provides a low-cost platform for the fabrication of efficient materials for various applications such as batteries, fuel cells and water splitting.
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38.
  • Mahar, Ihsan Ali, et al. (författare)
  • Glucose sensing via green synthesis of NiO-SiO2 composites with citrus lemon peel extract
  • 2024
  • Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 35:7
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, NiO-SiO2-based composites were synthesized through low-temperature aqueous chemical growth utilizing a facile, low-cost, and environmentally friendly approach. The composite systems were prepared using a combination of silica gel and citrus lemon peel extract. Due to the remarkable green chemicals in orange peel extract, porous nanostructures have been developed with thin sheet-like properties. The composite materials were examined in terms of their crystalline structure, morphology, optical band gap, and surface chemical composition. An advanced non-enzymatic glucose sensor developed from NiO-SiO2 composites exhibits rich surface oxygen vacancies and abundant catalytic sites. Based on sample 2, cyclic voltammetry revealed a linear glucose concentration range between 0.1 and 20 mM, chronoamperometry exhibited glucose concentration ranges between 0.1 and 14 mM, and linear sweep voltammetry revealed glucose concentration ranges from 0.1 to 10 mM. In enzymatic glucose sensors, the minimum level of detection was estimated to be 0.08 mM. A number of sensor characterization parameters were examined, including selectivity, stability, reproducibility, and real-time applications. In addition, electrochemical impedance spectroscopy (EIS) has shown that the NiO-SiO2 composite performs well in non-enzymatic glucose sensing due to its low charge transfer resistance and high electrochemical active surface area (ECSA). NiO-SiO2 composites could have significant biomedical, energy conversion, and storage applications based on the results obtained.
  •  
39.
  • Mangrio, Sanjha, et al. (författare)
  • Advanced Urea Precursors Driven NiCo2O4 Nanostructures Based Non-Enzymatic Urea Sensor for Milk and Urine Real Sample Applications
  • 2023
  • Ingår i: Biosensors. - : MDPI. - 2079-6374. ; 13:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The electrochemical performance of NiCo2O4 with urea precursors was evaluated in order to develop a non-enzymatic urea sensor. In this study, NiCo2O4 nanostructures were synthesized hydrothermally at different concentrations of urea and characterized using scanning electron microscopy and X-ray diffraction. Nanostructures of NiCo2O4 exhibit a nanorod-like morphology and a cubic phase crystal structure. Urea can be detected with high sensitivity through NiCo2O4 nanostructures driven by urea precursors under alkaline conditions. A low limit of detection of 0.05 and an analytical range of 0.1 mM to 10 mM urea are provided. The concentration of 006 mM was determined by cyclic voltammetry. Chronoamperometry was used to determine the linear range in the range of 0.1 mM to 8 mM. Several analytical parameters were assessed, including selectivity, stability, and repeatability. NiCo2O4 nanostructures can also be used to detect urea in various biological samples in a practical manner.
  •  
40.
  • Mugheri, Abdul Qayoom, et al. (författare)
  • A Low Charge Transfer Resistance CuO Composite for Efficient Oxygen Evolution Reaction in Alkaline Media
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2613-2620
  • Tidskriftsartikel (refereegranskat)abstract
    • An efficient, simple, environment-friendly and inexpensive cupric oxide (CuO) electrocatalyst for oxygen evolution reaction (OER) is demonstrated. CuO is chemically deposited on the porous carbon material obtained from the dehydration of common sugar. The morphology of CuO on the porous carbon material is plate-like and monoclinic crystalline phase is confirmed by powder X-ray diffraction. The OER activity of CuO nanostructures is investigated in 1 M KOH aqueous solution. To date, the proposed electrocatalyst has the lowest possible potential of 1.49 V versus RHE (reversible hydrogen electrode) to achieve a current density of 20 mA/cm(2) among the. CuO based electrocatalysts and has Tafel slope of 115 mV dec(-1). The electrocatalyst exhibits an excellent long-term stability for 6 hours along with significant durability. The enhanced catalytic active centers of CuO on the carbon material are due to the porous structure of carbon as well as strong coupling between CuO-C. The functionalization of metal oxides or other related nanostructured materials on porous carbon obtained from common sugar provides an opportunity for the development of efficient energy conversion and energy storage systems.
  •  
41.
  • Mugheri, Abdul Qayoom, et al. (författare)
  • An advanced and efficient Co3O4/C nanocomposite for the oxygen evolution reaction in alkaline media
  • 2019
  • Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:59, s. 34136-34143
  • Tidskriftsartikel (refereegranskat)abstract
    • The design of efficient nonprecious catalysts for the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) is a necessary, but very challenging task to uplift the water-based economy. In this study, we developed a facile approach to produce porous carbon from the dehydration of sucrose and use it for the preparation of nanocomposites with cobalt oxide (Co3O4). The nanocomposites were studied by the powder X-ray diffraction and scanning electron microscopy techniques, and they exhibited the cubic phase of cobalt oxide and porous structure of carbon. The nanocomposites showed significant OER activity in alkaline media, and the current densities of 10 and 20 mA cm(-2) could be obtained at 1.49 and 1.51 V versus reversible hydrogen electrode (RHE), respectively. The impedance study confirms favorable OER activity on the surface of the prepared nanocomposites. The nanocomposite is cost-effective and can be capitalized in various energy storage technologies.
  •  
42.
  • Mugheri, Abdul Qayoom, et al. (författare)
  • Chemically Coupled Cobalt Oxide Nanosheets Decorated onto the Surface of Multiwall Carbon Nanotubes for Favorable Oxygen Evolution Reaction
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2660-2667
  • Tidskriftsartikel (refereegranskat)abstract
    • Cobalt oxide has been widely investigated among potential transition metal oxides for the electrochemical energy conversion, storage, and water splitting. However, they have inherently low electronic conductivity and high corrosive nature in alkaline media. Herein, we propose a promising and facile approach to improve the conductivity and charge transport of cobalt oxide Co3O4 through chemical coupling with well-dispersed multiwall carbon nanotubes (MWCNTs) during hydrothermal treatment. The morphology of prepared composite material consisting of nanosheets which are anchored on the MWCNTs as confirmed by scanning electron microscopy (SEM). A cubic crystalline system is exhibited by the cobalt oxide as confirmed by the X-ray diffraction study. The Co, O, and C are the only elements present in the composite material. FTIR study has indicated the successful coupling of cobalt oxide with MWCNTs. The chemically coupled cobalt oxide onto the surface of MWCNTs composite is found highly active towards oxygen evolution reaction (OER) with a low onset potential 1.44 V versus RHE, low overpotential 262 mV at 10 mAcm(-2) and small Tafel slope 81 mV dec(-1). For continuous operation of 40 hours during durability test, no decay in activity was recorded. Electrochemical impedance study further revealed a low charge transfer resistance of 70.64 Ohms for the composite material during the electrochemical reaction and which strongly favored OER kinetics. This work provides a simple, low cost, and smartly designing electrocatalysts via hydrothermal reaction for the catalysis and energy storage applications.
  •  
43.
  • Mugheri, Abdul Qayoom, et al. (författare)
  • Efficient tri-metallic oxides NiCo2O4/CuO for the oxygen evolution reaction
  • 2019
  • Ingår i: RSC ADVANCES. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 9:72, s. 42387-42394
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, a simple approach was used to produce nonprecious, earth abundant, stable and environmentally friendly NiCo2O4/CuO composites for the oxygen evolution reaction (OER) in alkaline media. The nanocomposites were prepared by a low temperature aqueous chemical growth method. The morphology of the nanostructures was changed from nanowires to porous structures with the addition of CuO. The NiCo2O4/CuO composite was loaded onto a glassy carbon electrode by the drop casting method. The addition of CuO into NiCo2O4 led to reduction in the onset potential of the OER. Among the composites, 0.5 grams of CuO anchored with NiCo2O4 (sample 2) demonstrated a low onset potential of 1.46 V vs. a reversible hydrogen electrode (RHE). A current density of 10 mA cm(-2) was achieved at an over-potential of 230 mV and sample 2 was found to be durable for 35 hours in alkaline media. Electrochemical impedance spectroscopy (EIS) indicated a small charge transfer resistance of 77.46 ohms for sample 2, which further strengthened the OER polarization curves and indicates the favorable OER kinetics. All of the obtained results could encourage the application of sample 2 in water splitting batteries and other energy related applications.
  •  
44.
  • Mugheri, Abdul Qayoom, et al. (författare)
  • Facile efficient earth abundant NiO/C composite electrocatalyst for the oxygen evolution reaction Electronic supplementary information (ESI) available. See DOI: 10.1039/c8ra10472g
  • 2019
  • Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 9:10, s. 5701-5710
  • Tidskriftsartikel (refereegranskat)abstract
    • Due to the increasing energy consumption, designing efficient electrocatalysts for electrochemical water splitting is highly demanded. In this study, we provide a facile approach for the design and fabrication of efficient and stable electrocatalysts through wet chemical methods. The carbon material, obtained by the dehydration of sucrose sugar, provides high surface area for the deposition of NiO nanostructures and the resulting NiO/C catalysts show higher activity towards the OER in alkaline media. During the OER, a composite of NiO with 200 mg C can produce current densities of 10 and 20 mA cm(-2) at a bias of 1.45 V and 1.47 V vs. RHE, respectively. Electrochemical impedance spectroscopy experiments showed the lowest charge transfer resistance and the highest double layer capacitance in the case of the NiO/C composite with 200 mg C. The presence of C for the deposition of NiO nanostructures increases the active centers and consequently a robust electrocatalytic activity is achieved. The obtained results in terms of the low overpotential and small Tafel slope of 55 mV dec(-1) for non-precious catalysts are clear indications for the significant advancement in the field of electrocatalyst design for water splitting. This composite material based on NiO/C is simple and scalable for widespread use in various applications, especially in supercapacitors and lithium-ion batteries.
  •  
45.
  • Mustafa, Elfatih, et al. (författare)
  • Efficient Ni–Fe layered double hydroxides/ZnO nanostructures for photochemical water splitting
  • 2019
  • Ingår i: Journal of Solid State Chemistry. - : Academic Press. - 0022-4596 .- 1095-726X. ; 273, s. 186-191
  • Tidskriftsartikel (refereegranskat)abstract
    • Zinc oxide (ZnO) nanostructures are widely investigated for photocatalytic applications but the functional properties are limited by the fast carrier recombination rate, which is an intrinsic property of ZnO. To optimize the recombination rate of ZnO, a study is carried out in which it is covered with Ni-Fe layered double hydroxides and synergistic effects are created which boosted the photocatalytic activity of ZnO. The nanostructured materials are synthesized by the low temperature aqueous chemical growth and electrodeposition methods. These nanostructures are characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) technique. SEM study has revealed a Ni–Fe LDH coated ZnO NRs. The powder XRD has showed a cubic phase of the Ni-Fe layered double hydroxide on the ZnO NRs having an excellent crystalline quality. The optical characterization has shown low scattering of light for the Ni–Fe LDH coated ZnO NRs sample. The sample prepared with deposition time of 25 s showed excellent photochemical water splitting properties compared to counter photo-anodes in alkaline media. The photo response was highly stable and fast. The incident photon to current conversion efficiency for the photo-anode of Ni–Fe(LDHs)/ZnO over 25 s was 82% at a maximum absorption of 380 nm compared to the pristine ZnO NRs which has 70% at the same wavelength. This study is providing a simple, cost effective, earth abundant and environment friendly methodology for the fabrication of photo-anodes for diverse applications specifically water oxidation and solar radiation driven water splitting.
  •  
46.
  •  
47.
  • Qayoom Mugheri, Abdul, et al. (författare)
  • Co3O4/ NiO bifunctional electrocatalyst for water splitting
  • 2019
  • Ingår i: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 306
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of noble metal free and active bifunctional catalysts for water splitting in alkaline media is highly demanded but very challenging. Herein, synergetic effects developed between two nonprecious metal oxides, Co3O4 and NiO, are reported, with the resulting composite showing promising properties as a catalyst for alkaline water electrolysis. The activity of the composite material towards both the HER and the OER was enhanced and the dynamic potential decreased, as compared with its counterparts. Importantly, low Tafel slopes of 101 and 61 mVdec(-1) are found for the composite catalyst for OER and HER respectively. EIS measurements revealed a decreased impedance response of the composite dominated by the intermediate frequency relaxation, related to the adsorption of intermediates. Moreover, based on the structural features the improved catalytic activity of the composite is also due to high electroactive surface area, swift electron transfer kinetics, and excellent electrical chemical coupling between Co3O4 and NiO. (c) 2019 Elsevier Ltd. All rights reserved.
  •  
48.
  • Saeed, Sumbul, et al. (författare)
  • Realization of Peptone Biosensor Based on Newly Prepared NiO Nanostructures
  • 2017
  • Ingår i: Sensor Letters. - : American Scientific Publishers. - 1546-198X .- 1546-1971. ; 15:10, s. 822-826
  • Tidskriftsartikel (refereegranskat)abstract
    • The present study authenticates the fabrication of nickel oxide porous shaped nanostructure by hydrothermal method. The novel and functionalized nickel oxide nanomaterial were visualized by using scanning electron microscopy (SEM) and X-ray diffraction techniques (XRD). NiO nanomaterial advertised sensitive, selective and attracted morphology for the development of peptone biosensor. Phenylalanine displays a soft template and growth directing agent for the developing of nickel oxide low dimension nanostructures. The nickel oxide nanomaterial together with protease possesses tremendous role towards the oxidation potential phenomena and transfer of anodic electro-catalytic current for the peptone. The generation of low potential electrochemical signals exhibited the determination of peptone by utilizing different electrochemical techniques for the given concentration ranging from 0.1 mM to 2.5 mM with the measured limit of detection about 0.002 mM with a sensitivity of 107200 μA/mMCm2. The well-defined and highly developed sensor system provides the standard platform for the fabrication and functioning of new devices that are helpful for the determination of many biological macromolecules. The presented peptone biosensor is highly selective, sensitive, and reproducible that could also be useful for the determination of peptone from various milk samples.
  •  
49.
  • Shah, Aqeel Ahmed, et al. (författare)
  • Facile synthesis of copper doped ZnO nanorods for the efficient photo degradation of methylene blue and methyl orange
  • 2020
  • Ingår i: Ceramics International. - Oxford : Elsevier. - 0272-8842 .- 1873-3956. ; 46:8, part A, s. 9997-10005
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, zinc oxide (ZnO) nanorods are doped with copper by low temperature aqueous chemical growth method using different concentrations of copper 5 mg, 10 mg, 15 mg and 20 mg and labeled as sample 1, 2, 3 and 4 respectively. The morphology and phase purity of nanostructures was investigated by scanning electron microscopy, and powder X-ray diffraction techniques. The optical characterization was carried out through UV–Vis spectrophotometer. The band gap of coper doped ZnO has brought reduction at 250–600 nm and it indicates the fewer time for the recombination of electron and hole pairs, thus enhanced photo degradation efficiency is found. ZnO exhibits nanorods like shape even after the doping of copper. The photo degradation efficiency for the two chronic dyes such as methyl orange MO and methylene blue MB was found to be 57.5% and 60% respectively for a time of 180 mints. This study suggests that the copper impurity in ZnO can tailor its photocatalytic activity at considerable rate. The proposed photo catalysts are promising and can be used for the waste water treatment and other environmental applications. © 2019 Elsevier Ltd and Techna Group S.r.l.
  •  
50.
  • Shah, Aqeel Ahmed, et al. (författare)
  • Tin as an Effective Doping Agent into ZnO for the Improved Photodegradation of Rhodamine B
  • 2021
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2529-2537
  • Tidskriftsartikel (refereegranskat)abstract
    • We have fabricated ZnO nano rods by hydrothermal method and successively doped them with tin (Sn) using different concentrations of 25, 50, 75 and 100 mg of tin chloride. XRD of the fabricated structures showed that ZnO possess hexagonal wurtzite phase. Scanning electron microscopy (SEM) was used to explore the morphology and it shows nanorod like morphology for all samples and no considerable change in the structural features were found. The dimension of nanorod is 200 to 300 nm. The doped materials were then investigated for their photo catalytic degradation of environmental pollutant Rhodamine B. The performance of doped ZnO is compared with the pristine ZnO. Scanning electron microscopy (SEM) was used to explore the morphology and it shows nanorod like morphology for all samples and no considerable change in the structural features were found. The dimension of nanorod is 200 to 300 nm. XRD of the fabricated structures showed that ZnO possess hexagonal wurtzite phase. Photo catalytic activity of rhodamine B was investigated under UV light and a maximum degradation efficiency of 85% was obtained. The optical property reveals the reduction in band gap of upto 17.14% for 100 mg Sn doped ZnO. The degradation is followed by the pseudo order kinetics. The produced results are unique in terms of facile synthesis of Sn doped ZnO and excellent photo degradation efficiency, therefore these materials can be used for other environmental applications.
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