Browsing by Author "Haldar, Krishna K."

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    Construction of three-dimensional marigold flower-shaped Ni3V2O8 for efficient solid-state supercapacitor applications
    (John Wiley and Sons Inc, 2022-06-13T00:00:00) Haldar, Krishna K.; Biswas, Rathindranath; Arya, Anil; Ahmed, Imtiaz; Tanwar, Shweta; Sharma, Achchhe Lal
    Development of binary spinel-type mixed metal oxide and fabrication various morphological heterostructure nanomaterials having two distinct metals paid a wide attention in emerging field. Here, we prepared three-dimensional (3D) marigold flower-like Ni3V2O8 structure via a simple and facile technique for electrochemical supercapacitor applications. 3D Ni3V2O8 with thick petals as cathode materials exhibits high specific capacitance of 263.12 F g?1 at a scan rate of 0.5�mA cm?2. The high energy density of 32.98 W h kg?1 at power density of 189.96 W kg?1 is obtained by the cathode formation of marigold flower-shaped Ni3V2O8, indicating excellent ions accessibility and large charge storage ability of Ni3V2O8 structure. It is also observed that even after 5000 cycles charging-discharging profile analysis, Ni3V2O8 cathode retains 32% of its initial capacitance along with 100% Coulombic efficiency. This higher capacitance retention strengthens its adoption as a potential candidate for supercapacitor application. � 2022 John Wiley & Sons Ltd.
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    Experimental investigations on morphology controlled bifunctional NiO nano-electrocatalysts for oxygen and hydrogen evolution
    (Elsevier Ltd, 2022-09-27T00:00:00) Manjunath, Vishesh; Bimli, Santosh; Biswas, Rathindranath; Didwal, Pravin N.; Haldar, Krishna K.; Mahajan, Mangesh; Deshpande, Nishad G.; Bhobe, Preeti A.; Devan, Rupesh S.
    Developing a single electrocatalyst effective for both oxygen and hydrogen evolution remains challenging. Although an attempt to utilize a single electrocatalyst for overall water splitting is made, there still exist several issues of efficiency and stability of the electrocatalyst. Hence, the present study reports on morphology-controlled NiO electrocatalyst, a single electrocatalyst for oxygen and hydrogen evolution. The cubic phase NiO nanoparticles and nanoplates of diameter and thickness <10 nm delivered surface-to-volume ratios of 0.078 and 0.083, respectively. XRD and TEM confirm the formation of NiO nanostructures, where morphology transformed independently of the chemical composition. XPS and EXAFS confirm the 2+ oxidation state of Ni ions and its octahedral coordination with oxygen. The 0D nanoparticles providing a larger surface area and active sites offered the overpotentials of 373 and 268 mV for OER and HER activity, respectively, and performed well than the 2D porous NiO nanoplates. The chronoamperometry and repetitive LSV cyclic studies confirmed the excellent long-term stability of 0D NiO nanoparticles in basic and acidic mediums during electrocatalytic water splitting reactions, owing to its increased electrochemically exposed active sites. � 2022 Hydrogen Energy Publications LLC