School Of Basic And Applied Sciences

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    Tunable photocatalytic water splitting and solar-to-hydrogen efficiency in ?-PdSe2monolayer
    (Royal Society of Chemistry, 2021-08-18T00:00:00) Jakhar, Mukesh; Kumar, Ashok
    Direct production of hydrogen from photocatalytic water splitting is a potential solution to overcome global energy crisis. Herein, based on first-principles calculations, we demonstrate that the two-dimensional ?-PdSe2 monolayer is a promising candidate for efficient photocatalytic water splitting in acidic and alkaline media as well as neutral medium with highly efficient solar-to-hydrogen efficiency. ?-PdSe2 monolayer shows low cleavage energy which endorses the possibility of its mechanical exfoliation from layered bulk ?-PdSe2. Remarkably, ?-PdSe2 monolayer is semiconducting with indirect band gap of 1.96 eV with perfect engulfing the redox potential of water in a wide range of pH of medium. ?-PdSe2 monolayer exhibits good light harvesting ability and adequate driving forces for water redox reaction in wide range of pH (0 to 12). Comprehensive investigation of pH dependent water splitting indicates that the ?-PdSe2 monolayer is a better candidate for efficient water splitting in alkaline media rather than acidic or neutral medium. In addition, high solar-to-hydrogen efficiency as high as ?17% is obtained that shows ?-PdSe2 monolayer a promising candidate for overall photocatalytic water-splitting. � The Royal Society of Chemistry.
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    Cu-Metal Organic Framework Derived Multilevel Hierarchy (Cu/CuxO@NC) as a Bifunctional Electrode for High-Performance Supercapacitors and Oxygen Evolution Reaction
    (American Chemical Society, 2023-05-25T00:00:00) Abbas, Zahir; Hussain, Nissar; Ahmed, Imtiaz; Mobin, Shaikh M.
    The development of a MOFs-derived multilevel hierarchy in a single step still remains a challenging task. Herein, we have synthesized novel Cu-MOF via a slow diffusion method at ambient temperature and further utilized it as a precursor source for MOF-derived multilevel hierarchy (Cu/CuxO@NC, x = 1 and 2). This studies suggest that the organic ligands served as a source of an N-doped carbon matrix encapsulated with metal oxide nanoparticles which were confirmed by various characterization techniques; further BET analysis reveals a surface area of 178.46 m2/g. The synthesized multilevel hierarchy was utilized as an electro-active material in a supercapacitor that achieved a specific capacitance of 546.6 F g-1 at a current density of 1 A g-1 with a higher cyclic retention of 91.81% after 10 000 GCD cycles. Furthermore, the ASC device was fabricated using Cu/CuxO@NC as the positive electrode and carbon black as the negative electrode and utilized to enlighten the commercially available LED bulb. The fabricated ASC device was further employed for a two-electrode study which achieved a specific capacitance of 68 F g-1 along with a comparable energy density of 13.6 Wh kg-1. Furthermore, the electrode material was also explored for the oxygen evolution reaction (OER) in an alkaline medium with a low overpotential of 170 mV along with a Tafel slope of 95 mV dec-1 having long-term stability. The MOF-derived material has high durability, chemical stability, and efficient electrochemical performance. This work provides some new thoughts for the design and preparation of a multilevel hierarchy (Cu/CuxO@NC) via a single precursor source in a single step and explored multifunctional applications in energy storage and an energy conversion system. � 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.