Chemistry - Research Publications

Permanent URI for this collectionhttps://kr.cup.edu.in/handle/32116/37

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Author: search.filters.author.Ahmed, ImtiazSubject: search.filters.subject.Hydrogen evolution reactions

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    Bio-assisted Synthesis of Au/Rh Nanostructure Electrocatalysts for Hydrogen Evolution and Methanol Oxidation Reactions: Composition Matters!
    (American Chemical Society, 2023-08-11T00:00:00) Biswas, Rathindranath; Dastider, Saptarshi Ghosh; Ahmed, Imtiaz; Biswas, Sayani; Mondal, Krishnakanta; Haldar, Krishna Kanta
    In the field of catalysis, bimetallic nanostructures have attracted much interest. Here, we discuss the effect of Au/Rh bimetallic composition-tuned nanostructure and electrocatalytic activity. A simple bio-assisted technique was used to fabricate multiple Au:Rh nanoplate ratios (25:75, 50:50, and 75:25). XRD and XPS studies show that both Au and Rh phases coexist in a bimetallic nanostructure, and electron microscopy confirms the formation of a triangle-shaped nanoplate. Au0.25Rh0.75 exhibited the maximum catalytic activity and good stability for hydrogen evolution reaction (HER) with an overpotential of 105 mV at a current density of 10 mA/cm2. On the other hand, Au0.50Rh0.50 exhibits a higher activity for methanol oxidation reaction (MOR) compared to the other compositions. Theoretical studies indicate that the electrocatalytic enhancement obtained for both HER and MOR relies on electronic modification effects of the surface, with the overall reaction energy profile being optimized due to Au/Rh d-band mixing. � 2023 American Chemical Society.
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    Coupling Nonstoichiometric Zn0.76Co0.24S with NiCo2S4Composite Nanoflowers for Efficient Synergistic Electrocatalytic Oxygen and Hydrogen Evolution Reactions
    (American Chemical Society, 2022-12-15T00:00:00) Biswas, Rathindranath; Thakur, Pooja; Ahmed, Imtiaz; Rom, Tanmay; Ali, Mir Sahidul; Patil, Ranjit A.; Kumar, Bhupender; Som, Shubham; Chopra, Deepak; Paul, Avijit Kumar; Ma, Yuan-Ron; Haldar, Krishna Kanta
    Transition-metal sulfide-based composite nanomaterials have garnered extensive interest not only for their unique morphological architectures but also for exploring as a noble-metal-free cost-effective, durable, and highly stable catalyst for electrochemical water splitting. In this work, we synthesized in situ nonstoichiometric Zn0.76Co0.24S with NiCo2S4binary composite flowers (Zn0.76Co0.24S/NiCo2S4) in one step by thermal decomposition of Zn2[PDTC]4and Ni[PDTC]2complexes by a solvothermal process in a nonaqueous medium from their molecular precursor, and their potential application in electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was investigated. Field-emission scanning electron microscopy and transmission electron microscopy analyses revealed the flower-shaped morphology of as-synthesized Zn0.76Co0.24S/NiCo2S4. Again, the structural and chemical compositions were confirmed through powder X-ray diffraction and X-ray photoelectron spectroscopy studies, respectively. The as-obtained 3D flower-type Zn0.76Co0.24S/NiCo2S4nanostructure was further subject to electrochemical OER and HER in alkaline and acidic media, respectively. Zn0.76Co0.24S/NiCo2S4showed low overpotential values of 248 mV (Tafel slope, 85 mV dec-1) and 141 mV (Tafel slope, 79 mV dec-1) for OER and HER activities, respectively, due to the synergistic effects of Zn0.76Co0.24S and NiCo2S4. Several long-term stability tests also affirmed that the Zn0.76Co0.24S/NiCo2S4composite nanostructure is a highly stable and efficient electrocatalyst toward OER and HER activities as compared to the recently reported superior bifunctional electrocatalysts as well as state-of-the-art materials. � 2023 American Chemical Society. All rights reserved.
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    Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2�8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions
    (Royal Society of Chemistry, 2022-01-28T00:00:00) Singh, Harjinder; Ahmed, Imtiaz; Biswas, Rathindranath; Mete, Shouvik; Halder, Krishna Kamal; Banerjee, Biplab; Haldar, Krishna Kanta
    Among the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2�8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2�8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed. This journal is � The Royal Society of Chemistry.