Browsing by Author "Kumari, R"

Now showing 1 - 3 of 3
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    Corrosion inhibition and adsorption mechanism of Morus nigra on mild steel in acidic medium: A sustainable and green approach
    (2021-12) Kumar, H; Sharma, S; Kumari, R
    Morus nigra (Mulberry leaves) was tested as a green inhibitor for mild steel (MS) in 0.5 M HCl by theoretical, surface study, and experimental techniques. The impedance, polarization, microscopy, Langmuir, and DFT (computational) techniques were used for the adsorption and corrosion inhibition study. The experimental and theoretical study supports each other results. Adsorption parameters were observed by Langmuir, Gaussian09W (DFT), and BIOVIA Materials Studio Softwares. The surface study was carried out by metallurgical microscopy technique. The theoretical study includes chemical potential, electron-donating power, chemical hardness, HOMO, LUMO, metal inhibitor interaction energy, adsorption energy, etc. UV-visible, NMR, and FTIR studies show that aspartic acid is the major constituent present in the mulberry leaves extract. A 91.62 % corrosion protection was provided by the Morus nigra at 1000 ppm. Polarization study proved mixed inhibition. The green inhibitor follows both physical and chemical modes of adsorption. The biochemical and chemical oxygen demand of unused acid left after the gravimetric study was found in an acceptable range.
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    Developments in conducting polymer-, metal oxide-, and carbon nanotube-based composite electrode materials for supercapacitors: a review
    (2024-03) Tundwal, A; Kumar, H; Binoj, B; Sharma, R; Kumar, G; Kumari, R; Dhayal, A; Yadav, A; Singh, D; Kumar, P
    Supercapacitors are the latest development in the field of energy storage devices (ESDs). A lot of research has been done in the last few decades to increase the performance of supercapacitors. The electrodes of supercapacitors are modified by composite materials based on conducting polymers, metal oxide nanoparticles, metal–organic frameworks, covalent organic frameworks, MXenes, chalcogenides, carbon nanotubes (CNTs), etc. In comparison to rechargeable batteries, supercapacitors have advantages such as quick charging and high power density. This review is focused on the progress in the development of electrode materials for supercapacitors using composite materials based on conducting polymers, graphene, metal oxide nanoparticles/nanofibres, and CNTs. Moreover, we investigated different types of ESDs as well as their electrochemical energy storage mechanisms and kinetic aspects. We have also discussed the classification of different types of SCs; advantages and drawbacks of SCs and other ESDs; and the use of nanofibres, carbon, CNTs, graphene, metal oxide– nanofibres, and conducting polymers as electrode materials for SCs. Furthermore, modifications in the development of different types of SCs such as pseudo-capacitors, hybrid capacitors, and electrical double-layer capacitors are discussed in detail; both electrolyte-based and electrolyte-free supercapacitors are taken into consideration. This review will help in designing and fabricating high-performance supercapacitors with high energy density and power output, which will act as an alternative to Li-ion batteries in the future.
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    Exploring the Influence of Temperature and Time on the Formation and Properties of 3D Flower-Like MoS2 Nanostructures Synthesized via Hydrothermal Method
    (2023-08) Kumari, R; Kumar, R
    In this study, a simple hydrothermal method was employed to synthesize 3D flower-like MoS2 nanostructures. The influence of different synthesis temperatures on the structural, electronic, optical and morphological properties of the MoS2 nanostructures was thoroughly investigated, and the optimal temperature was identified as 220 °C. Additionally, we conducted further optimization to determine the most suitable reaction time, which was found to be 24 h. The characterization of the synthesized MoS2 nanostructures, employing various techniques such as X-ray diffraction, Raman spectroscopy, Mott-Schottky analysis, UV–vis- NIR spectroscopy and field emission scanning electron microscopy, unveiled well-defined crystallinity, reduced thickness and uniform morphology, under the optimized conditions. Notably, as the temperature increased from 180 °C to 220 °C, the band gap of MoS2 nanostructures exhibited a notable increase from 1.72 to 2.35 eV. The Mott-Schottky analysis further confirmed our findings, revealing lower values of flat band potential and carrier concentration for the optimized temperature (220 °C), indicative of higher crystallinity with fewer defects. These comprehensive findings not only underscore the significant impact of temperature and time on the properties of MoS2 nanostructures but also hold promising implications for diverse applications, including sensing, energy storage, as well as photocatalysis for hydrogen evolution reactions and organic pollutant degradation