Browsing by Author "Vivek Kumar Agrahari"

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Efficacy of Methylammonium Iodobismuthate: A Green Catalyst for Reduction of Nitrate to Ammonia
(American Chemical Society, 2025) Vivek Kumar Agrahari; Abhik Bhuin; Ankur Yadav; Sujoy Sarkar; Subha Sadhu; Daya Shankar Pandey
Ammonia (NH3) is vital in agriculture and industry, yet its large-scale production remains energy-intensive and environmentally hostile. Herein, for the first time we report the development of lead-free nontoxic hexagonal methylammonium iodobismuthate metal halide perovskite (MABI) as a highly efficient and sustainable electrocatalyst for green ammonia production from nitrate reduction. The unique structure of MABI, featuring an isolated BiI6octahedron stabilized by a methylammonium cation, offers a highly tunable electronic environment required for nitrogen activation and hydrogenation. The experimental and computational studies categorically established the formation of an interconnected pure hexagonal structure with a band gap of ∼2.1 eV. Electrocatalytic nitrate reduction revealed that MABI displays a remarkable ammonia yield (27.53 μg mg–1h–1) with excellent stability and a quite impressive Faradaic efficiency (40%). This work highlights the potential of halide bismuthate perovskites as an alternative to traditional catalysts to produce ammonia in ambient conditions that address the dual challenges of energy efficiency and environmental sustainability. © 2025 American Chemical Society
Fabrication of a solution-processed low voltage TFT by using colloid 2D ZnO nanosheets and its application as a UV photodetector
(Royal Society of Chemistry, 2025) Abhik Bhuin; Akhilesh Kumar Yadav; Utkarsh S. Pandey; Debdyuti Mukherjee; Vivek Kumar Agrahari; Caroline Ponraj; Subha Sadhu; Bhola Nath Pal; Sujoy Sarkar
ZnO nanostructures have been extensively employed in optoelectronic devices because of their unique optoelectronic properties; however, these devices have been developed using physical vapor deposition techniques, which are costly and need a state-of-the-art fabrication facility. Hence, a solution-processed, cost-effective, low-temperature method is required for the large-scale fabrication of 2D material-based electronic devices. In this contribution, we report template, polymer, and surfactant-free wet chemical synthesis of 2D ZnO nanostructures having dimensions of ∼200 nm and thickness of ∼30 nm following the hydrothermal method. Detailed structural, morphological, and optical investigation revealed the formation of a pure hexagonal wurtzite phase of ZnO nanosheets. Utilizing the as-synthesized nanosheets, solution-processed thin film transistors (TFTs) are fabricated under low annealing temperatures that exhibit a high carrier mobility of 8.05 cm2 V−1 s−1 and an on-off ratio of ∼105. Also, these TFTs show high photosensitivity and can be used as UV detectors. Thus, our study highlights low-temperature facile fabrication of 2D ZnO TFTs, which may have promising applications in electronic displays, logic circuits, UV detectors, biosensors, and portable electronics. © 2025 The Royal Society of Chemistry.
Impact of polymorphism vs. shape of titania nanocrystals on the hydrogen evolution reaction
(Royal Society of Chemistry, 2024) Ankur Yadav; Vivek Kumar Agrahari; Yuriy Pihosh; Mamiko Nakabayashi; Wojciech Nogala; Balendu Sekhar Giri; Kazunari Domen; Daya Shankar Pandey; Bhavana Gupta; Subha Sadhu
Herein, we investigated the impact of polymorphism vs. dimension control of titania nanocrystals towards hydrogen generation. Two different forms of titania nanoparticles have been synthesized following the solvothermal method, leading to the formation of two distinct physicochemical features. Detailed structural, morphological, and optical studies revealed that the formation of titania nanorods correspond to rutile while granular particles correspond to the anatase phase. Among various titania polymorphs, anatase is well known for its superior photocatalytic activity; however, to our surprise, the as-synthesized rutile nanorods exhibited higher catalytic activity in comparison to anatase spheres, and hydrogen evolution was considerably enhanced after the addition of a minute amount of Pt as the co-catalyst. Thus, despite the higher catalytic activity of anatase, the enhanced hydrogen evolution of rutile nanorods may be related to the creation of a 1D structure. Our study highlights the importance of considering not only TiO2 polymorphism but also shape and dimension in optimizing photocatalytic H2 production. © 2024 RSC.