Chemistry - Research Publications

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

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Author: search.filters.author.Haldar, Krishna Kanta

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    Bifunctional electrochemical OER and HER activity of Ta2O5 nanoparticles over Fe2O3 nanoparticles
    (Royal Society of Chemistry, 2023-08-23T00:00:00) Ahmed, Imtiaz; Burman, Vishal; Biswas, Rathindranath; Roy, Ayan; Sharma, Rohit; Haldar, Krishna Kanta
    Hydrogen production via electrocatalytic water splitting offers encouraging innovations for sustainable and clean energy production as an alternative to conventional energy sources. The improvement of extraordinarily dynamic electrocatalysts is of great interest for work on the performance of gas generation, which is firmly blocked due to the sluggish kinetics of the oxygen evolution reaction (OER). The development of highly efficient base metal catalysts for electrochemical hydrogen and oxygen evolution reactions (HER and OER) is a challenging and promising task. In the present work, a particle over particles of Fe2O3 and Ta2O5 was successfully produced by hydrothermal treatment. The prepared composite shows promising catalytic performance when used as an electrochemical catalyst for OER and HER in alkaline and acidic electrolytes with low overpotentials of 231 and 201 mV at 10 mV cm?2, small Tafel slopes of 71 and 135 mV dec?1, respectively, and good stability properties. The calculated electrochemical surface area (ECSA) for composites is five times higher than that of the original oxides. The result of the OER is significantly better than that of commercial IrO2 catalysts and offers a promising direction for the development of water-splitting catalysts. � 2023 The Royal Society of Chemistry.
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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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    Porous nanorods by stacked NiO nanoparticulate exhibiting corn-like structure for sustainable environmental and energy applications
    (Royal Society of Chemistry, 2023-07-20T00:00:00) Manjunath, Vishesh; Bimli, Santosh; Singh, Diwakar; Biswas, Rathindranath; Didwal, Pravin N.; Haldar, Krishna Kanta; Deshpande, Nishad G.; Bhobe, Preeti A.; Devan, Rupesh S.
    A porous 1D nanostructure provides much shorter electron transport pathways, thereby helping to improve the life cycle of the device and overcome poor ionic and electronic conductivity, interfacial impedance between electrode-electrolyte interface, and low volumetric energy density. In view of this, we report on the feasibility of 1D porous NiO nanorods comprising interlocked NiO nanoparticles as an active electrode for capturing greenhouse CO2, effective supercapacitors, and efficient electrocatalytic water-splitting applications. The nanorods with a size less than 100 nm were formed by stacking cubic crystalline NiO nanoparticles with dimensions less than 10 nm, providing the necessary porosity. The existence of Ni2+ and its octahedral coordination with O2? is corroborated by XPS and EXAFS. The SAXS profile and BET analysis showed 84.731 m2 g?1 surface area for the porous NiO nanorods. The NiO nanorods provided significant surface-area and the active-surface-sites thus yielded a CO2 uptake of 63 mmol g?1 at 273 K via physisorption, a specific-capacitance (CS) of 368 F g?1, along with a retention of 76.84% after 2500 cycles, and worthy electrocatalytic water splitting with an overpotential of 345 and 441 mV for HER and OER activities, respectively. Therefore, the porous 1D NiO as an active electrode shows multifunctionality toward sustainable environmental and energy applications. � 2023 The Royal Society of Chemistry.
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    BiFeO3/g-C3N4/f-CNF ternary nanocomposite as an efficient photocatalyst for methylene blue dye degradation under solar light irradiation
    (Elsevier Ltd, 2023-06-21T00:00:00) Deeksha; Kour, Pawanpreet; Ahmed, Imtiaz; Haldar, Krishna Kanta; Yadav, C.S.; Sharma, Surender Kumar; Yadav, Kamlesh
    The development of Perovskite oxide photocatalysts with superior dye degradation efficiency under solar light irradiation has gained attention in recent years, owing to their extraordinary flexibility, chemical composition, and tunability. Herein, we report the facile synthesis of a novel ternary composite composed of BiFeO3 (BFO) perovskite, g-C3N4, and functionalized carbon nanofibers (f-CNF), referred to as BFO/g-C3N4/f-CNF using a simple solution method as a photocatalyst to accelerate the degradation of methylene blue dye. Detailed structural and microstructural features confirm the formation of a ternary composite composed of BFO nanoparticles and f-CNFs mounted on g-C3N4 nanosheets. The photocatalytic activity of the sample for the degradation of methylene blue dye was studied in solar light using UV�visible spectroscopy. The BFO/g-C3N4/f-CNF ternary composite displays excellent photocatalytic activity with a degradation rate of 87 % after illumination for 120 min under solar light than BFO, g-C3N4, and binary composites BFO/g-C3N4 and BFO/f-CNF. The highest rate constant (k = 0.01675 min?1) for BFO/g-C3N4/f-CNF further confirms improved photocatalytic efficiency. The red shift in the UV�visible absorption spectrum of BFO/g-C3N4/f-CNF indicates a reduced band gap (1.9 eV) compared to that of pure BFO (2.28 eV) and g-C3N4 ( 2.72 eV). A decrease in the photoluminescence intensity of the ternary composite compared to that of BFO indicates the inhibition of photoexcited electron recombination which results in the availability of more charge carriers for the photocatalytic process. The enhanced efficiency of BFO/g-C3N4/f-CNF can be explained by the synergistic effect between BFO and g-C3N4 and the incorporation of f-CNF further promotes the migration rate of electrons from BFO to g-C3N4. � 2023 Elsevier B.V.
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    Efficient MoS2/V2O5 Electrocatalyst for Enhanced Oxygen and Hydrogen Evolution Reactions
    (Springer, 2023-04-29T00:00:00) Haldar, Krishna Kanta; Ahmed, Imtiaz; Biswas, Rathindranath; Mete, Shouvik; Patil, Ranjit A.; Ma, Yuan-Ron
    Electrochemical (EC) water splitting is a promising approach for the generation of renewable hydrogen (H2) fuels and oxygen (O2) evolution. Composite structured molybdenum disulphide (MoS2)/vanadium pentoxide (V2O5) with low overpotential is a promising electrocatalyst for anodic and cathodic material for an alternative energy source. We fabricated a flower shape MoS2/V2O5 composite via a hydrothermal approach where V2O5grew on the surface of the MoS2 petals. The unique flower-type composite structure alleviates the surface expansion of electrode material. The electrochemical studies show that the composite possesses good stability with low overpotential and smaller Tafel slope compared to its constituents. It has been found that the MoS2/V2O5 composite exhibits a stable rate performance under the current density of 10�mA�cm?2 which indicates that the MoS2/V2O5 composite might be a good candidate for both oxygen and hydrogen evolution reactions.; Graphical Abstract: [Figure not available: see fulltext.] � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Europium Molybdate/Molybdenum Disulfide Nanostructures with Efficient Electrocatalytic Activity for the Hydrogen Evolution Reaction
    (American Chemical Society, 2023-04-26T00:00:00) Ghosh, Debarati; Ghosal Chowdhury, Monojit; Biswas, Rathindranath; Haldar, Krishna Kanta; Patra, Amitava
    The design of hybrid nanostructures of molybdenum disulfide (MoS2) has been extensively explored as potent electrocatalysts for hydrogen generation reactions. Here, we report the in situ synthesis of a nanocomposite containing europium molybdate [Eu2(MoO4)3] and molybdenum disulfide (MoS2) for an enhanced electrochemical hydrogen evolution reaction (HER). The characteristic X-ray diffraction (XRD) peaks of both 2H-MoS2 and ?-Eu2(MoO4)3 confirm the formation of the nanocomposite. The nanoflower (NF) architecture of MoS2 coupled with flakes of europium molybdate is observed in the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, which lead to an enhanced surface area of the nanocomposite. Raman and X-ray photoelectron spectroscopy (XPS) studies reveal a variation in the layer thickness of MoS2 and a significant interfacial electronic interaction between Eu2(MoO4)3 and MoS2. As evident from the small onset potential of ?0.05 V vs reversible hydrogen electrode (RHE) and a lower overpotential value of 186 mV (at a current density of 10 mA/cm2), the nanocomposite outperforms pristine MoS2 nanoflowers in terms of electrocatalytic HER. The charge-transfer resistance of the nanocomposite (80.02 ?) is significantly low compared to pristine MoS2 (158.37 ?), thus confirming the enhanced interfacial charge transfer. The Tafel slope value of the nanocomposite (189 mV/dec) is notably less than that of pristine MoS2 (313 mV/dec), indicating the enhanced HER activity of the nanocomposite. The fabrication of lanthanide-containing MoS2 nanocomposites appears to be promising for an efficient electrocatalytic activity for the hydrogen evolution reaction. � 2023 American Chemical Society
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    Does Water Play a Crucial Role in the Growth of ZnO Nanoclusters in ZnO/Cu Catalyst?
    (American Chemical Society, 2023-05-04T00:00:00) Dastider, Saptarshi Ghosh; Panigrahi, Abhishek Ramachandra; Banerjee, Arup; Haldar, Krishna Kanta; Fortunelli, Alessandro; Mondal, Krishnakanta
    The catalytically active configuration of ZnO/Cu in the commercial ZnO/Cu/Al2O3 catalyst for methanol synthesis from CO2 is still not clear. In this study, we employ density functional theory based methods to shed light on the structure and stoichiometry of ZnO clusters both free in the gas phase and also deposited on the Cu(111) surface under methanol synthesis conditions. Specifically, we investigate the structural evolution of ZnO clusters in the presence of hydrogen and water. We find that the stability of ZnO clusters increases with the concentration of water until the ratio of Zn and OH in the clusters reaches 1:2, with a morphological transition from planar to 3D configurations for clusters containing more than 4 Zn atoms. These clusters exhibit weak interaction with CO2, and water is predicted to block the active center. The Cu(111) surface plays an important role in enhancing the adsorption of CO2 on the ZnO/Cu(111) systems. We infer that ZnO nanostructures covered with OH species may be the morphology of the ZnO during the methanol synthesis from the hydrogenation of CO2 on the industrial catalyst. � 2023 American Chemical Society.
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    NiS/MoS2 Anchored Multiwall Carbon Nanotube Electrocatalyst for Hydrogen Generation and Energy Storage Applications
    (John Wiley and Sons Inc, 2023-04-05T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Iqbal, Muzahir; Roy, Ayan; Haldar, Krishna Kanta
    Although sulfide-based materials are known to be efficient catalysts for oxygen evolution reactions (OER), hydrogen evolution reactions (HER), and supercapacitor applications, improving the catalytic activity of sulfide materials for both electrochemical water splitting and supercapacitors remains a challenging problem. Here, an easy and one-step integrated methodology is implemented to develop NiS/MoS2 anchored multiwall carbon nanotubes (MWCNT/NiS/MoS2) catalysts that can effectively and robustly catalyze both the HER and OER. The MWCNT/NiS/MoS2 hybrid composite offers the lowest overpotential of 201 mV and 193 mV to achieve a current density of 10 mA/cm2 and ?10 mA/cm2 with a small Tafel slope of 58 mV/dec 41 mV/dec for OER and HER, respectively, in alkaline and acidic conditions. The obtained multi-walled carbon nanotubes anchored with intertwined NiS/MoS2 have a significant number of active sites and defects throughout the structure. The hybrid composite electrode delivered a specific capacitance of >371.45 F/g at 2 A/g in a two-electrode system, along with high energy density of 51.63 Wh/kg (ED) along with the power density (PD) of 953.63 W/kg, and good capacitance retention ?82% after 2000 cycles. Therefore, a tandem electron transfer mechanism between NiS and MoS2 (MoS2?NiS) is believed to have an electrical synergistic effect that promotes both HER and OER activity. This research opens a new path for the construction of multi-component, cheap electrocatalysts that are highly effective for overall water splitting and energy storage applications. � 2023 Wiley-VCH GmbH.
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    Synergistic photophysical and electrochemical response of Te @ PANI for energy harvesting
    (Springer, 2023-01-07T00:00:00) Rani, Pinki; Jewariya, Yogesh; Haldar, Krishna Kanta; Biswas, Rathindranath; Alegaonkar, Prashant S.
    Materials with synergistic functionality are of great importance in consumer electronics. We report on the preparation and assessments of Te @ PANI composite for energy conversion and storage application. Initially, (5�15%) Te @ PANI composites were synthesized by the facile, room temperature, time and cost-effective solid-state synthesis technique followed by characterizations using Fourier transform infra-red, UV-Visible, energy dispersive spectroscopic including X-ray diffractometry and field electron scanning microscopy. Te exfoliates polymeric segments of PANI by bonding benzenoid rings through sulphonated impurity sites which have a profound impact on symmetry molecular bond vibrations. Its analysis is presented. In photophysical application, both dark and luminescent I-V measurements have been performed that showed a linear variation with minimum photo-resistance offered by 10% composite and reaching current > 10�mA under 1.5�V biased conditions. In storage response, Te @ PANI supercapacitor devices are dominating in inductive coupling over capacitive coupling by ten times. Corresponding shunt impedance is seen to be favourably lower for 10% composition, and respective charge transfer impedance has also followed identical behaviour over other classes of samples. The quality factor of the device for 10% is found to be almost twelve times better. However, at a low scan rate (10�mV/s), the presence of Te has changed the tendency of ion migration, thereby, reducing the magnitude of ion current by about three times with an increase in Te from 5 to 15%. Thus, fabricated composite demonstrated synergistic aspects of energy. � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Facile Fabrication of Ni9S8/Ag2S Intertwined Structures for Oxygen and Hydrogen Evolution Reactions
    (John Wiley and Sons Inc, 2022-12-21T00:00:00) Biswas, Rathindranath; Ahmed, Imtiaz; Manna, Priyanka; Mahata, Partha; Dhayal, Rajendra S.; Singh, Amol; Lahtinen, Jouko; Haldar, Krishna Kanta
    Here, we report the fabrication of the unique intertwined Ni9S8/Ag2S composite structure with hexagonal shape from their molecular precursors by one-pot thermal decomposition. Various spectroscopic and microscopic techniques were utilized to confirm the Ni9S8/Ag2S intertwined structure. Powder X-ray Powder Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis suggest that there is an enrichment of Ni9S8 phase in Ni9S8/Ag2S. The presence of Ag2S in Ni9S8/Ag2S improves the conductivity by reducing the interfacial energy and charge transfer resistance. When Ni9S8/Ag2S is employed as an electrocatalyst for electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity, it requires a low overpotential of 152 mV for HER and 277 mV for OER to obtain the geometrical current density of 10 mA cm?2, which is definitely superior to that of its components Ni9S8 and Ag2S. This work provides a simple design route to develop an efficient and durable electrocatalyst with outstanding OER and HER performance and the present catalyst (Ni9S8/Ag2S) deserves as a potential candidate in the field of energy conversion systems. � 2022 Wiley-VCH GmbH.