| 1. |
- 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
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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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| 2. |
- 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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| 3. |
- 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
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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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| 4. |
- 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
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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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| 5. |
- Aftab, Umair, et al.
(författare)
-
The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
- 2019
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Ingår i: Catalysis Science & Technology. - : ROYAL SOC CHEMISTRY. - 2044-4753 .- 2044-4761. ; 9:22, s. 6274-6284
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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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| 6. |
- 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
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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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| 7. |
- Solangi, Muhammad Yameen, et al.
(författare)
-
In-situ growth of nonstoichiometric CrO0.87 and Co3O4 hybrid system for the enhanced electrocatalytic water splitting in alkaline media
- 2023
-
Ingår i: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 48:93, s. 36439-36451
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Tidskriftsartikel (refereegranskat)abstract
- The development of electrocatalysts for electrochemical water splitting has received considerable attention in response to the growing demand for renewable energy sources and environmental concerns. In this study, a simple hydrothermal growth approach was developed for the in-situ growth of non-stoichiometric CrO0.87 and Co3O4 hybrid materials. It is apparent that the morphology of the prepared material shows a heterogeneous aggregate of irregularly shaped nanoparticles. Both CrO0.87 and Co3O4 have cubic crystal structures. Its chemical composition was governed by the presence of Co, Cr, and O as its main constituents. For understanding the role CrO0.87 plays in the half-cell oxygen evolu-tion reaction (OER) in alkaline conditions, CrO0.87 was optimized into Co3O4 nanostructures. The hybrid material with the highest concentration of CrO0.87 was found to be highly efficient at driving OER reactions at 255 mV and 20 mA cm(-2). The optimized material demonstrated excellent durability for 45 h and a Tafel slope of 56 mV dec(-1). Several factors may explain the outstanding performance of CrO0.87 and Co3O4 hybrid materials, including multiple metallic oxidation states, tailored surface properties, fast charge transport, and surface defects. An alternative method is proposed for the preparation of new generations of electrocatalysts for the conversion and storage of energy. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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| 8. |
- 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
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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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| 9. |
- Ali Soomro, Razium, et al.
(författare)
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Controlled synthesis and electrochemical application of skein-shaped NiO nanostructures
- 2015
-
Ingår i: Journal of Solid State Electrochemistry. - : Springer Verlag (Germany). - 1432-8488 .- 1433-0768. ; 19:3, s. 913-922
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Tidskriftsartikel (refereegranskat)abstract
- A simple, economical and mild solution chemistry method was used to synthesize diverse nickel oxide (NiO) nanostructures employing methionine as a growth-directing agent. The as-synthesized NiO nanostructures were observed to possess a unique skein-shape morphology with uniform spherical distribution. The NiO nanoskein (NiO NSk) formation was extensively studied using X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) techniques, respectively. The unique NiO NSks exhibited better electrocatalytic activity towards glucose oxidation in alkaline media, enabling the development of a highly sensitive non-enzymatic glucose sensor. The observed analytical properties included high sensitivity (1915 mu A mM(-1) cm(-2)), wide linear range (0.1-5.0 mM), low detection limit (0.7 mu M), higher stability and reproducibility. Moreover, the sensor is selective in the presence of interfering species such as ascorbic acid (AA), uric acid (UA) and dopamine (DP) during the non-enzymatic glucose sensing. The worthy-of-notice electrocatalytic activity and economical feasible preparation of NiO NSk-shaped electroactive material for direct glucose-sensing applications make the present study of high interest for the fabrication of low-cost devices. A NiO NSk-based glucose sensor has also been employed for glucose determination in human serum with adequate results, suggesting high potential for the routine monitoring of glucose from biotechnology, clinical and food industry samples.
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| 10. |
- Ali Soomro, Razium, et al.
(författare)
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Development of sensitive non-enzymatic glucose sensor using complex nanostructures of cobalt oxide
- 2015
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier. - 1369-8001 .- 1873-4081. ; 34, s. 373-381
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Tidskriftsartikel (refereegranskat)abstract
- The study reports the synthesis of cobalt oxide (Co3O4) nanostructures and their application in enzyme free electrochemical sensing of glucose. The synthesized nanostructures were elaborately characterized via number of analytical techniques including scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The as-synthesized nanostructures of Co3O4 were found to exhibited nanodisc like morphology with the size dimension in range of 300-500 nm. The obtained morphological features were evaluated for their electrochemical potential towards oxidation of glucose which enabled development of sensitive (27.33 mu A mM(-1) cm(-2)), and stable enzyme free glucose sensor. In addition, the developed sensor showed excellent linearity (r(2)=0.9995), wide detection range (0.5-5.0 mM), lower detection limit (0.8 mu M) and extreme selectivity towards glucose in the presence of common interferents like dopamine (DP), ascorbic acid (AA) and uric acid (UA). The successfully application of developed sensor for real blood glucose analysis further reflects its capability for routine glucose measurement.
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| 11. |
- Ali Soomro, Razium, et al.
(författare)
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Glycine-assisted preparation of Co3O4 nanoflakes with enhanced performance for non-enzymatic glucose sensing
- 2015
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Ingår i: MATERIALS EXPRESS. - : AMER SCIENTIFIC PUBLISHERS. - 2158-5849. ; 5:5, s. 437-444
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Tidskriftsartikel (refereegranskat)abstract
- In this study a simple, inexpensive and efficient route is proposed to synthesise attractive cobalt oxide (Co3O4) nanostructures using glycine as an effective growth controller and regulator. The as-synthesised Co3O4 nanostructures were observed to possess unique nanoflake shape morphological features with highly dense distribution. The formation of Co3O4 nanoflakes (Co3O4 NFKs) was elaborately explored using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM) respectively. The unique Co3O4 nanoflakes were known to possess excellent electro-catalytic potential for the oxidation of glucose in alkaline medium. This potential property allowed successful development of highly sensitive (1180 mu A mM(-1) cm(-2)), selective and stable non-enzymatic glucose sensor. In addition, the developed sensor had a wide working range (0.1-5.0 mM), low limit of detection (0.7 mu M), and excellent reproducibility, besides the capability of analysing real blood glucose samples.
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| 12. |
- Ali Soomro, Razium, et al.
(författare)
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Practice of diclofenac sodium for the hydrothermal growth of NiO nanostructures and their application for enzyme free glucose biosensor
- 2016
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Ingår i: Microsystem Technologies. - : SPRINGER. - 0946-7076 .- 1432-1858. ; 22:10, s. 2549-2557
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Tidskriftsartikel (refereegranskat)abstract
- In this study diclofenac sodium (DFS), an analgesic drug has been employed as an effective template for the synthesis of NiO nanostructures. The NiO nanostructures were synthesised using low temperature hydrothermal growth method, both in the presence and absence of the DFS drug. The synthesised nanostructures were studied for their structural, compositional and electrochemical properties using scanning electron microscopy, X-ray diffraction and cyclic voltammetry. The synthesised nanostructures were then utilised for the modification of glassy carbon electrode which were then utilised for the electro-catalytic enzyme free glucose sensing in alkaline media. The competitive experiments suggested that although, both nanostructures possess excellent capability of glucose sensing, the NiO nanoflakes modified electrode was found to be twice as much as sensitive (2584 A mu A mM(-1) cm(-2)) as nanoflowers based electrode (1154 A mu A mM(-1) cm(-2)). The NiO nanoflakes based sensor further demonstrated excellent anti-interference potential in the presence of common interferents like uric acid, ascorbic acid and dopamine. In addition, the successful application NiO nanoflakes based sensor to determine real blood glucose concentration further suggest its feasibility for real sample analysis.
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| 13. |
- Baloach, Qurrat-ul-Ain, et al.
(författare)
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A Robust, Enzyme-Free Glucose Sensor Based on Lysine-Assisted CuO Nanostructures
- 2016
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 16:11
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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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| 14. |
- Bhatti, Adeel Liaquat, et al.
(författare)
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Nanostructured Co3O4 electrocatalyst for OER : The role of organic polyelectrolytes as soft templates
- 2021
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 398
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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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| 15. |
- Hussain Ibupoto, Zafar, et al.
(författare)
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Glycine-assisted synthesis of NiO hollow cage-like nanostructures for sensitive non-enzymatic glucose sensing
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 5:24, s. 18773-18781
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a highly sensitive non-enzymatic glucose sensor was developed based on NiO hollow cage-like nanostructures (NiO HCs). The novel nanostructures were synthesized using hydrothermal growth route with glycine employed as an effecient growth director. The synthesized NiO HCs were characterized by using scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS) X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques for morphological, compositional and structural determination respectively. The prepared NiO HCs were directly integrated to be structured electrodes exhibiting enhanced electrocatalytic performance toward the oxidation of glucose with high sensitivity (2476.4 mu A mM(-1) cm(-2)), low detection limit (LOD) (0.1 mu M), wide detection range (0.1-5.0 mM) (r(2) = 0.9997) and excellent reproducibility. The developed nonenzymatic glucose sensor further demonstrated excellent anti-interference property in the presence of common interferents such as uric acid (UA), dopamine (DP) and ascorbic acid (AS). The role of glycine molecules as an efficient growth directing agent with a plausible growth mechanism has also been highlighted. In addition, the NiO HCs modified electrode was also used to analyze glucose concentration in human serum samples. The excellent sensing performance can be attributed to the unique morphology, which allowed increased electron transfer passages with lower charge transfer resistance, and enhanced molecular approach during electrochemical sensing offered from nanoscale "hollow cage" units of NiO structures.
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| 16. |
- Khokhar, Shams Parveen, et al.
(författare)
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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
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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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| 17. |
- Mugheri, Abdul Qayoom, et al.
(författare)
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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
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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.
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| 18. |
- Mugheri, Abdul Qayoom, et al.
(författare)
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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
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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.
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| 19. |
- Mugheri, Abdul Qayoom, et al.
(författare)
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Facile efficient earth abundant NiO/C composite electrocatalyst for the oxygen evolution reaction Electronic supplementary information (ESI) available. See DOI: 10.1039/c8ra10472g
- 2019
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Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 9:10, s. 5701-5710
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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.
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| 20. |
- Qayoom Mugheri, Abdul, et al.
(författare)
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Co3O4/ NiO bifunctional electrocatalyst for water splitting
- 2019
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Ingår i: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 306
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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.
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| 21. |
- Soomro, Razium Ali, et al.
(författare)
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Electrochemical sensing of glucose based on novel hedgehog-like NiO nanostructures
- 2015
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 209, s. 966-974
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Tidskriftsartikel (refereegranskat)abstract
- The present study reports the synthesis of novel hedgehog-like NiO nanostructures via hydrothermal method using L-cysteine as a structure directing agent. The as-synthesized hedgehog-like NiO nanostructures were characterized by scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS) X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques for morphological, compositional and structural studies respectively. The prepared NiO nanostructures were applied for the design and engineering of non-enzymatic glucose sensor in the alkaline medium. The electrode material for glucose sensing based on the hedgehog-like NiO nanostructures demonstrated extremely high electrochemical response with high sensitivity (1052.8 mu A mM(-1) cm(-2)), low detection limit (LOD) (1.2 mu M), high selectivity, wide linear range (0.1-5.0 mu M) (R-2 = 0.9982) and the outstanding reproducibility. A plausible growth mechanism has been proposed to explain the formation process of the hedgehog-like NiO nanostructures. The excellent sensing performance can be attributed to the unique surface architectures, which enhanced the electron transfer rate and the molecular approach during the electrochemical sensing of glucose. Furthermore, the sensor showed excellent performance for the quantification of glucose in real blood sera reflecting universal nature of the presented glucose sensor. (C) 2014 Elsevier B.V. All rights reserved.
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| 22. |
- Tahira, Aneela, et al.
(författare)
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An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media
- 2019
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Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry. - 2044-4753 .- 2044-4761. ; 9:11, s. 2879-2887
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Tidskriftsartikel (refereegranskat)abstract
- Developing highly active nonprecious metal and binder free bifunctional electrocatalysts for water splitting is a challenging task. In this study, we used a simple strategy to deposit a nickel iron layered double hydroxide (NiFeLDH) onto cobalt oxide (Co3O4) nanowires. The cobalt oxide nanowires are covered with thin nanosheets of NiFeLDH forming a core shell structure. The Co3O4 nanowires contain the mixed oxidation states of Co2+ and Co3+, and the surface modification of Co3O4 nanowires has shown synergetic effects due to there being more oxygen defects, catalytic sites, and enhanced electronic conductivity. Further, the core shell structure of Co3O4 nanowires demonstrated a bifunctional activity for water splitting in 1 M KOH aqueous solution. From the hydrogen evolution reaction (HER), a current density of 10 mA cm - 2 is achieved at a potential of - 0.303 V vs. reversible hydrogen electrode (RHE). Meanwhile for the case of the oxygen evolution reaction (OER), a current density of 40 mA cm - 2 is measured at a potential of 1.49 V vs. RHE. Also, this electrocatalyst has shown a considerable long- term stability of 15 h for both the HER and the OER. Importantly, electrochemical impedance spectroscopy has shown that the NiFeLDH integration onto cobalt oxide exhibited around 3 fold decrease of charge transfer resistance for both the HER and the OER in comparison with pristine cobalt oxide films, which reveals an excellent electrocatalytic activity for both faradaic processes. All these results confirm that the proposed electrocatalyst can be integrated into an efficient water splitting system.
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