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| 2. |
- Gupta, Divyani, et al.
(författare)
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High yield selective electrochemical conversion of N-2 to NH(3)via morphology controlled silver phosphate under ambient conditions
- 2022
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:38, s. 20616-20625
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Tidskriftsartikel (refereegranskat)abstract
- Development of a highly active catalyst for the synthesis of ammonia via the electrochemical dinitrogen reduction reaction (e-NRR) is an immense challenge. We report the modification of metallic Ag with inorganic phosphate to obtain Ag3PO4 as an effective electrocatalyst for the e-NRR in alkaline media under ambient conditions. The designed Ag3PO4 catalyst can effectually suppress the HER. The e-NRR activity was improved by fine-tuning the morphology by a template free one-pot synthesis. The synthesised Ag3PO4 having cuboidal morphology is shown to have superior activity and stability towards the e-NRR witnessed from a high faradaic efficiency of 26.67%, yield rate of 456.75 mu g h(-1) mg(cat)(-1) and TOF value of 0.46 h(-1) at a positive potential of 0 V vs. RHE in 0.1 M KOH. Careful examination of any N-contaminants present in catalyst/electrolyte/gas-feed is carried out by UV-vis spectroscopy and gas-purification methods prior to e-NRR measurements to eliminate any false NH3 production. Also, the true source of NH3 production is confirmed by means of N-15-isotope labelling experiments via(1)H-NMR spectroscopy.
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| 3. |
- Gupta, Divyani, et al.
(författare)
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Local electrocatalytic activity of PtRu supported on nitrogen-doped carbon nanotubes towards methanol oxidation by scanning electrochemical microscopy
- 2021
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 9:37, s. 21291-21301
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by treating HNO3-oxidized carbon nanotubes (CNTs) in an NH3 flow at different temperatures. PtRu nanoparticles were decorated over NCNTs. The PtRu catalysts were prepared by an impregnation-reduction method from metal chloride precursors with a total metal loading of about 10 wt%. The electrocatalytic activity with respect to methanol oxidation was studied using electrochemical and scanning electrochemical microscopy (SECM) measurements. Transmission electron microscopy revealed the spherical shape and narrow particle size distribution of the PtRu particles over NCNTs with average particle sizes of similar to 3-5 nm. A detailed X-ray photoelectron spectroscopy study was performed to quantitatively identify different nitrogen functional groups and to evaluate their role in the observed enhanced catalytic activity towards methanol oxidation. The determination of the local electrocatalytic activity of the proposed catalyst towards methanol oxidation and simultaneous evaluation of the intermediates produced during methanol oxidation were achieved using SECM. Density functional theory studies were performed to understand the adsorption sites of methanol and intermediates on different reactive sites and to investigate possible reaction mechanisms.
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| 4. |
- Gupta, Divyani, et al.
(författare)
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Self-powered NH3 synthesis by trifunctional Co2B-based high power density Zn-air batteries
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:23, s. 12223-12235
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Tidskriftsartikel (refereegranskat)abstract
- The electrochemical production of NH3 by Zn-air batteries is a viable and economical approach to realize sustainable and competent energy conversion. We report the environment friendly, cost-effective, and energy efficient sonochemical synthesis of amorphous Co2B nanosheets for trifunctional electrocatalysis. The catalyst exhibits a high NH3 yield rate (2.98 mg h(-1) mg(cat.)(-1)), F.E (20.45%), and TOF of 0.74 h(-1) at -0.3 V vs. RHE, thereby unveiling an outstanding performance for the artificial ammonia synthesis. The reliable and true NH3 production is premediated by following rigorous protocol that involves the purification of gas supplies, elimination of N-contaminants, and quantification of NH3 by different methods, UV-Vis spectroscopy and N-15(2) isotope labelling experiments. More interestingly, DFT calculations on the Co2B catalyst surface shed light on the efficient NRR owing to the presence of Co active sites and possible HER suppression. The optimized Co2B catalyst shows outstanding oxygen bifunctional activity. When employed as an air-cathode for Zn-air batteries, it exhibited remarkable electrocatalytic activity delivering an open circuit potential of 1.45 V with a high power density of 500 mW cm(-2) and an energy density of 1078 W h kg(-1), which can perform NH3 generation with an overall NH3 production yield rate of 1.048 mg h(-1) mg(cat.)(-1).
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| 5. |
- Kaur, Sukhjot, et al.
(författare)
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Efficient CO2 utilization and sustainable energy conversion via aqueous Zn-CO2 batteries
- 2023
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- Looking towards the economical and efficient carbon dioxide (CO2) utilization, metal-CO2 batteries uphold a great potential to enhance the efficiency of CO2 conversion to fuels. Pertaining to this, we have fabricated B, N -containing carbon with tubular morphology (C-BN@600) derived from ionic liquid (IL) and metal-organic framework (MOF) composite as cathode catalyst with Zn foil anode for aqueous rechargeable Zn-CO2 battery. The C-BN@600 catalyst demonstrate a remarkable activity towards electrochemical CO2 reduction to methanol with a Faradaic efficiency of 74% and a Yield rate of 2665 mu g h-1 mg-cat..1 The assembled battery consumes CO2 continuously and electrochemically convert it to methanol during discharge and simultaneously produces electrical energy with a remarkable energy density of 330 Wh kg- 1 and a power density of 5.42 mW cm-2 which is stable for more than 12 days (>300 h, 800 cycles) at 1 mA cm-2, providing a platform to serve a dual purpose of CO2 reduction and energy storage.
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