Browsing by Author "Sharma, Rohit"

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    Access to carbon nanofiber composite hydrated cobalt phosphate nanostructure as an efficient catalyst for the hydrogen evolution reaction
    (Frontiers Media S.A., 2023-02-23T00:00:00) Ahmed, Imtiaz; Biswas, Rathindranath; Sharma, Rohit; Burman, Vishal; Haldar, Krishna Kanta
    Attractive technology for producing sustainable hydrogen with water electrolyzers was foreseen as one of the most promising ways to meet the increasing demands of renewable resources and electricity storage. Mainly used for the efficient generation of H2, water electrolysis involving hydrogen evolution reactions (HERs) depends on efficient and affordable electrocatalysts. Hydrogen is an effective fuel that can be produced by splitting water. Hence, the search for highly efficient HER catalysts is a major challenge as efficient hydrogen evolution catalysts are sought to replace catalysts such as platinum. Here, we describe a low-cost and highly effective electrocatalyst for the proper incorporation of the HER electrocatalyst with low overpotential, effective charge transfer kinetics, low Tafel slope, and good durability. By using a simple hydrothermal approach to produce Co3(PO4)2.8H2O/CNF, it is possible to attach Co3(PO4)2.8H2O to the surface of carbon nanofibers (CNFs), which also exhibit remarkable HER activity at an overpotential of 133�mV and produce a current density of 10�mA/cm2 and a 48�mV/decade for the Tafel slope. Large electrochemical surface areas and easy charge transfer from Co3(PO4)2.8H2O to the electrode through conductive Co3(PO4)2.8H2O/CNF composites are the reasons for the improved performance of Co3(PO4)2.8H2O/CNF. Copyright � 2023 Ahmed, Biswas, Sharma, Burman and Haldar.
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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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    Effect of lattice defects on the structural and optical properties of Ni1 − XAgXO (where X = 0.0, 0.01, 0.03, 0.05, 0.10 and 0.15) nanoparticles
    (Springer, 2018) Sharma, Rohit; Yadav, Kamlesh
    The Ni1 − XAgXO (where X = 0, 0.01, 0.02, 0.03, 0.05, 0.10, and 0.15) nanoparticles are synthesized by sol–gel technique. The effects of Ag-doping in NiO nanoparticle on the structural and optical properties are studied. XRD analysis confirms that the prepared samples are single phase and oxygen deficient in nature. The unit cell volume decreases with the increase in the Ag-doping content. The crystallite size decreases from 23 to 19 nm with increasing the Ag-doping content up to X = 0.10. The strain increases with increase in Ag-doping concentration. FESEM analysis confirms that the pure sample of NiO is quasi-spherical and this shape is deformed as the Ag content increases in the NiO samples. The increase in the agglomeration of nanoparticles with the increase in doping content is also observed. UV–Visible analysis shows that the calculated optical band gap of the pure NiO sample is 3.70 eV which is less than the reported value 4.42 eV of NiO nanoparticles. The optical band gap increases as the Ag-doping content increases in the host NiO lattice. The change in band gap is increased rapidly for the X = 0.01 sample and then become slow for the rest of the samples. FT–IR analysis gives all the information regarding the functional group present in the samples. The effect of disorder created due to Ag-doping in NiO lattice leads to the formation of lattice defects and affects the structural and optical properties, which have been discussed in this paper in detail.