| 1. |
- 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.
|
|
| 2. |
- 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.
|
|
| 3. |
- 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.
|
|
| 4. |
- 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.
|
|
| 5. |
- 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.
|
|
| 6. |
- 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.
|
|
| 7. |
- 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.
|
|
| 8. |
- 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.
|
|
| 9. |
- 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.
|
|
| 10. |
- Ujan, Zaheer Ahmed, et al.
(författare)
-
The Crystal Disorder into ZnO with Addition of Bromine and Its Outperform Role in the Photodegradation of Methylene Blue
- 2022
-
Ingår i: Journal of cluster science. - : SPRINGER/PLENUM PUBLISHERS. - 1040-7278 .- 1572-8862. ; 33:1, s. 281-291
-
Tidskriftsartikel (refereegranskat)abstract
- In this research work, bromine (Br) is successfully doped into ZnO nanostructures using solvothermal method. The morphology, crystalline features, and composition of Br doped ZnO nanostructures were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X ray spectroscopy (EDX) respectively. These newly prepared nanostructured materials were tested as photocatalysts for the photodegradation of methylene blue (MB) in aqueous solution under UV light. The kinetic rate constants were observed in the order (20% Br/ZnO > 15% Br/ZnO > 10% Br/ZnO > 5% Br/ZnO >pristine ZnO), thus they are indicating that the increasing Br dopant level has linear effect on the photodegradation of MB. The photocatalytic degradation efficiency of 60% was achieved for the pristine ZnO during the irradiation of UV light for 5 h, however 20% Br doped ZnO nanostructures has shown enhanced degradation efficiency of 97.63% during the irradiation of UV light for short interval of time of 2.2 h. The 20% Br/ZnO describes the highest rate constant value of (24.13 x 10(-3) min(-1)), for time period of 2.2 h and this values is about 8 and 4 times higher than the pristine ZnO (3.72 x 10(-3) min(-1)) and 5% Br/ZnO (6.13 x 10(-3) min(-1)), respectively. The obtained results of 20% Br doped ZnO sample are superior or equal in performance than the recently reported works. The catalytic mechanism is also proposed and it indicates the role of electrons coming from the bromine ion might act as radical for the degradation of MB. The present approach is simpler, environment friendly, scalable and could be of great consideration for the diverse energy and environment related applications. Graphic
|
|
