Department Of Physics
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Item Aging impact of Se powder on the electrochemical properties of Molybdenum selenide: Supercapacitor application(Elsevier Ltd, 2022-02-10T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.In the present report, we have studied the impact of aging on selenium (Se) powder in hydrazine hydrate (act as reducing agent) during synthesis of pure molybdenum selenide (MoSe2) material. The MoSe2 as electrode material is prepared via single-step hydrothermal technique with aging Se powder in reducing agent for zero, one, and three days. The structural, microstructural, and chemical nature analysis of the samples was done via XRD, FESEM, and FTIR tools whereas the electrochemical study was performed via CV, GCD, and EIS techniques. The optimized material coded as M 39 (three days aged sample with pH 9) shows a high specific capacitance (Cs) of 368 F g?1 at the current density of value 0.5 A g?1 along with an energy density of 51 Wh kg?1 and power density of 250 W kg?1. Based on the electrode's electrochemical outcomes, it may be indicated that the electrochemical performance of MoSe2 material upsurges as the aging of Se increases from zero to three days. From the obtained results it is could be predicted that the M 39 material may stand appropriate for commercial supercapacitors. � 2022Item Structural and electrochemical performance of carbon coated molybdenum selenide nanocomposite for supercapacitor applications(Elsevier Ltd, 2021-12-14T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.Among the recent trends of supercapacitor electrode materials, transition metal dichalcogenides based composite materials have become popular due to their ability to have high electronic conductivity, variable oxidation states, large surface area, a porous structure. Herein we report, a composite material based on MoSe2 as electrode prepared using a standard single-step hydrothermal strategy. The structural and morphological study of the prepared material confirms the formation of the composite. The specific surface area has been estimated using BET technique and found to 522 m2 g ? 1 with average pore diameter as 4.6 nm. In all prepared composite electrodes, M@AC 1:5 electrode exhibits the highest specific capacity of 514 F g ? 1 at a scan rate of 10 mV s ? 1 for potential window 1 V in KOH electrolyte solution. The electrochemical impedance spectroscopy (EIS) study of the M@AC 1:5 electrode shows good agreement with cyclic voltammetry and galvanostatic charge-discharge storage mechanism. The aqueous symmetric cell fabricated of M@AC 1:5 with 6 M KOH electrolyte exhibits energy and power density 39.4 Wh kg?1 and 704.5 W kg?1 respectively. It shows long cycle stability with 90% capacitance retention and 100% coulombic efficiency even after 10,000 cycles. Further, the symmetric cell of M@AC 1:5 material was applied for lighting red LED, which illuminated for 22 min. The charging /discharging mechanism has been proposed based on finding of results through different characterizations. The asymmetric supercapacitor has also been designed using two different electrodes (first M@AC 1:5 and second synthetic MWCNT) and shows energy density of 14.9 Wh kg?1 and power density of 496 W kg?1 respectively. The capacitance retention is maintained up to 86.6% while coulombic efficiency recorded 100% for 10,000 cycles. Thus, obtained results highly encouraging and appropriate for the commercial applications. � 2021 Elsevier LtdItem Enhanced Electrochemical Performance of Hydrothermally Synthesized NiS/ZnS Composites as an Electrode for Super-Capacitors(Springer, 2021-08-22T00:00:00) Asghar, Ali; Yousaf, Muhammad Imran; Shad, Naveed Akhtar; Munir Sajid, M.; Afzal, Amir Muhammad; Javed, Yasir; Razzaq, Aamir; Shariq, Mohammad; Gulfam, Qurrat-ul-ain; Sarwar, Muhammad; Sharma, Surender K.In this study, nickel sulfide (NiS), zinc sulfide (ZnS), and their composites have been synthesized by using surfactant driven hydrothermal method. Synthesized materials are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy, UV�Vis and Photoluminescence spectroscopy. XRD results have shown the presence of corresponding structural planes. Crystallite size was much smaller (15�nm) in the case of ZnS nanomaterials, whereas, composite materials have shown size comparable to NiS nanomaterials. SEM images presented morphology of star-like, spherical, and mixture of two for NiS, ZnS, and NiS/ZnS nanocomposites respectively. EDX spectrum of composite materials showed Nickel, Zinc, and Sulfur, indicating the purity of the synthesized composite. Electrochemical measurements i.e. cyclic voltammetry and galvanostatic charge�discharge were determined for all three materials. Maximum specific capacitance is obtained as 1594.68 F�g?1 at a scan rate of 5�mV�S?1 for NiS/ZnS composite materials whereas a charging/discharging time of 461.97�s is observed. The composite materials have shown 95.4% retention for applied for 3000 charging�discharging cycles. The favorable behavior of NiS/ZnS composites indicated their potential as an electrode material for pseudo-capacitors. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Enhanced capacitive behaviour of graphene nanoplatelets embedded epoxy nanocomposite(Springer, 2021-01-06T00:00:00) Raval, Bhargav; Sahare, P.D.; Mahapatra, S.K.; Banerjee, I.For the development of advanced polymer nanocomposite processability, high-quality and cost-efficiency plays a crucial role which combines mechanical robustness with functional electrochemical properties. In this study, we fabricated the epoxy/graphene nanocomposite (EGNC) with different wt% ratio of graphene nanoplatelets (GNPs). The EGNCs were fabricated through a solution mixing process and used it as an electrode to enhance electrochemical properties. The GNPs and EGNCs characterized using XRD, Raman spectroscopy, ATR FT-IR, and FE-SEM for the structural conformation and surface morphological study. The electrochemical analysis results show significant improvement in the specific capacitance in the EGNC samples as compared to the blank epoxy film. Specific capacitance 17.74 Fg?1 was recorded at 10 mVs?1 scan rate in 1.0�M KOH electrolyte solution for the 1.0 wt% EGNC film by cyclic voltammetry analysis. The Galvanostatic charge�discharge and Ragone plots also show mended results by the addition of GNPs. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.Item Highly stable supercapacitive performance of one-dimensional (1D) brookite TiO2 nanoneedles(Royal Society of Chemistry, 2016) Devan, R.S.; Ma, Y.-R.; Patil, R.A.; Lukas, S.-M.We report the highly stable supercapacitive performance of one-dimensional (1D) nanoneedles of brookite (?) TiO2 synthesized on a conducting glass substrate. The 1D ?-TiO2 nanoneedles synthesized over a large area array utilizing hot-filament metal vapor deposition (HFMVD) were ?24-26 nm wide, ?650 nm long and tapered in a downward direction. X-ray photoemission spectroscopy (XPS) revealed their chemical properties and stoichiometric Ti and O composition. The 1D ?-TiO2 nanoneedles execute as parallel units for charge storage, yielding a specific capacitance of 34.1 mF g-1. Electrochemical impedance spectroscopy revealed that the large surface area and brookite crystalline nature of the 1D nanoneedles provided easy access to Na+ ions, and resulted in low diffusion resistance, playing a key role in their stable charging-discharging electrochemical mechanism. Moreover, the non-faradic mechanism of these nanoneedles delivered better durability and high stability up to 10000 cycles, and a columbic efficiency of 98%. Therefore, 1D ?-TiO2 nanoneedles hold potential as an electrode material for highly stable supercapacitive performance with long cycle lifetime. ? 2016 The Royal Society of Chemistry.