Browsing by Author "Subha Sadhu"

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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.
MAPI-MoS2 quantum dot composite films as active layers for efficient photovoltaics
(Royal Society of Chemistry, 2025) Subha Sadhu; Ankur Uttam Kambley; Talitha R.C. Santos; Abhijit Ganguly; Slavia Deeksha DSouza; Dilli Babu Padmanaban; Pagona Papakonstantinou; Paul Damian Maguire; V. Švrček; Davide Mariotti
In this work we have incorporated MoS2 quantum dots having outstanding optoelectronic properties with methyl ammonium lead iodide (MAPI) to form a composite absorber material for photovoltaic applications. The inclusion of MoS2 quantum dots in the perovskite layer improves the absorption and charge transport properties of the active layer, in part due to the quantum dots contributing to defect passivation at the MAPI grain interfaces. The photocurrent density increases when the MoS2 quantum dots are introduced in the device structure, resulting in efficiency improvements of 14% and 28% for devices fabricated in different laboratories. © 2025 RSC.
One-Step Synthesis and Deposition of Metal Oxides: NiO Quantum Dots as a Transport Layer for Perovskite Photovoltaics
(John Wiley and Sons Inc, 2024) Dilli babu Padmanaban; Subha Sadhu; Slavia Deeksha Dsouza; Warda Mushtaq; Zachary Holman; Vladimir Svrcek; Davide Mariotti
One-step synthesis and deposition of nickel oxide quantum dots using a gas-phase microplasma process is demonstrated and their applicability as a transport layer for solar cell devices is shown. The process uses a solid nickel metal wire as sacrificial electrode, and the concentration of oxygen gas required in the synthesis is investigated. The quantum dots are characterized for physical, chemical, and optical properties and critical process parameters such as the process throughput are also estimated. Direct one-step deposition directly on perovskite solar cells is carried out using a computer-controlled x–y stage and the performance of the solar cell device is assessed. © 2024 The Authors. Advanced Engineering Materials published by Wiley-VCH GmbH.