Department Of Chemistry
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Item 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.Item 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 KantaTransition-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.Item Green synthesis of hybrid papain/Ni3(PO4)2 rods electrocatalyst for enhanced oxygen evolution reaction(Royal Society of Chemistry, 2022-10-21T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Singh, Harjinder; Patil, Ranjit A.; Varshney, Rohit; Patra, Debabrata; Ma, Yuan-Ron; Haldar, Krishna KantaHydrogen production using electrocatalytic water splitting provides encouraging innovations for enduring and clean energy generation as an option in contrast to traditional energy sources. Improvement in exceptionally dynamic electrocatalysts is of tremendous interest for work on the proficiency of gas generation, which has been emphatically blocked because of the sluggish kinetics of the oxygen evolution reaction (OER). We have synthesized a noble rod-shaped papain/Ni3(PO4)2 catalyst, which was further explored for electrocatalytic OER activity. An environmentally benign approach was applied to prepare binary papain/Ni3(PO4)2 in the presence of papain obtained from green papaya fruit. The yield of Ni3(PO4)2 rod structures could be controlled by varying the amount of papain extract during reaction conditions. The morphology and structural properties of the biogenic papain/Ni3(PO4)2 electrocatalyst were investigated with various microscopic and spectroscopic techniques, for example, FE-SEM, XRD, XPS, and FTIR. To show how such a papain/Ni3(PO4)2 hybrid structure could deliver more remarkable electrocatalytic OER activity, we inspected the correlation between catalytic demonstrations of the papain/Ni3(PO4)2 catalyst and its constituents, and the role of papain on its own was studied during the OER process. A biosynthesised papain/Ni3(PO4)2 catalyst exhibits excellent electrochemical OER performance with the smallest overpotentials of 217 mV, 319 mV and 431 mV in alkaline, neutral and acidic conditions, respectively, at 10 mA cm?2 current density. Transport of ions and electrons is also assisted by the long peptide backbone present in papain, which plays an important role in boosting OER activity. Our results reveal that papain/Ni3(PO4)2 shows better electrocatalytic OER execution along with cyclic stability compared to its different counterparts, owing to synergism-assisted enhancement by several amino acids from papain with metal ions in Ni3(PO4)2 � 2022 The Royal Society of Chemistry.Item 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 KantaAmong 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.