Department Of Physics
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Item Predominated capacitive behavior of Ag-doped magnesium vanadate as a novel electrode material for supercapacitors(Elsevier Ltd, 2023-06-11T00:00:00) Umair, Muhammad; Shad, Naveed Akhtar; Hussain, S.; Jilani, Asim; Sajid, Muhammad Munir; Arshad, Muhammad Imran; Hasnain Rana, Hafiz Talha; Sharma, Surender Kumar; Mishra, Yogendra Kumar; Javed, YasirTransition metal vanadate nanostructures are getting significant importance as an efficient electrode material for modern energy storage applications. In this work, a simple hydrothermal method is employed for the synthesis of magnesium vanadate (MgV2O5) and Ag-doped magnesium vanadate (Ag doped MgV3O8) nanomaterials. The X-ray diffraction (XRD) analysis reveals the formation of an orthorhombic structure for magnesium vanadate, whereas the Ag-doped magnesium vanadate results in a monoclinic structure. Interestingly, the optical bandgap is observed to increase from 2.85 eV to 3.92 eV with the increase in Ag-doping as revealed from Tauc's plot of the UV-visible absorption spectrum. The electrochemical performance of magnesium vanadate electrodes is thoroughly investigated by cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy. The Ag-doped magnesium vanadate shows higher specific capacitance (Cs = 706 Fg?1) in comparison to undoped (325 Fg?1) at a current density J = 5 Ag?1. The theoretical investigations through Dunn's model demonstrate a major contribution arises from surface-controlled processes, which increase as high as 91% at scan rate of 60 mVsec?1. Our findings indicate that Ag-doping significantly improves the overall electrochemical response of magnesium vanadate as an efficient electrode material for supercapacitor applications. � 2023 Hydrogen Energy Publications LLCItem Bi-phasic BiPO4 prepared through template-assisted hydrothermal method with enhanced electrochemical response for hybrid supercapacitor applications(Springer Science and Business Media B.V., 2023-03-27T00:00:00) Monteles, Iara A.; Penha, Bruno V.; Fonseca, Weliton S.; Silva, Let�cia M. B.; Santos, Evelyn C. S.; de Souza, Luiz K. C.; Santos, C.C.; de Menezes, A.S.; Sharma, Surender K.; Javed, Yasir; Khawar, Muhammad R.; Tanaka, Auro A.; Almeida, Marcio A. P.Abstract: We report the structural evolution of BiPO4 prepared in aqueous under different synthesis conditions viz., templates and temperatures to explore their electrochemical performance for supercapacitor applications. The templates [(hexadecyltrimethylammonium bromide (CTAB)), sodium dodecyl sulfate (SDS)] were added in bismuth precursor solution at 60��C, alternatively ethylene glycol (EG), a less toxic additive was incorporated at 90��C. BiPO4 exhibits a monoclinic phase, whereas a hexagonal structure was observed with the addition of the templates SDS and CTAB. Interestingly, both monoclinic and hexagonal phases were obtained by the addition of EG. The presence of mixed phase was thoroughly validated through Raman spectra, where vibrational modes for both monoclinic and hexagonal phases of BiPO4-EG were witnessed. The effect of template was clearly seen through electron microscopy with a rod-like morphology with (no template) and unfaceted (template). The electrochemical behavior of the synthesized materials was investigated, and it was found that the mixed structure of BiPO4-EG exhibited the highest specific capacity (167.15 C�g?1) at a scan rate of 5�mV�s?1, good capacitance retention at high current densities of up to 10 A�g?1 and the lowest electrochemical series resistance (ESR) of 57 ?. Graphical abstract: [Figure not available: see fulltext.]. � 2023, The Author(s), under exclusive licence to Springer Nature B.V.Item Fabrication of activated carbon coated MSe2 (M=Mo, Co, and Ni) nanocomposite electrode for high-performance aqueous asymmetric supercapacitor(Elsevier B.V., 2023-03-09T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.Transition metal diselenides are trendy electrode materials for supercapacitors. The main reason behind it is their high specific capacitance. But, they suffer from poor electronic conductivity and agglomeration issues which hinder their practical use. Herein, we present the preparation of nanocomposites including transition metal diselenide MSe2 (M=Mo, Co, and Ni) with activated carbon using the facial hydrothermal route. Inspiring from the high electrochemical results of a hybrid nanocomposites symmetric cell, an aqueous asymmetric ultracapacitor cell (AUC) comprised of different shaped carbon-coated MSe2 (positive electrode) as well as activated carbon (AC) (negative electrode) has been fabricated. The NAC//6KOH//AC asymmetric cell displays the best outcomes among all fabricated devices. The specific capacitance observed is about 3740 F g?1 at 10 mV s?1. It delivers a high energy density of 69 Wh kg?1 along with a power density of 687 W kg?1 at 1 A g?1. The electrochemical results motivate us to explore the practical usability of the prepared NAC//6KOH//AC device via illuminating 26 red LED panels which glow for 26 min. The findings in this report indicate that MSe2-based nanocomposite has the scope and is a potential material in the energy storage field. � 2023 Elsevier B.V.Item Structural, Electrical and Electrochemical Properties of Fe Doped Orthosilicate Cathode Materials(Springer Nature, 2021-12-02T00:00:00) Singh, Nirbhay; Kanwar, Komal; Tanwar, Shweta; Sharma, A.L.; Yadav, B.C.We report the paper related to the effect of Fe doping on the Li2FexMn1?xSiO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) cathode materials synthesized by Sol-Gel technique. X-Ray Diffraction evidences the monoclinic structure with space group Pn(7) and crystal size decreases from 43 to 35�nm on doping Fe in Li2MnSiO4. Field emission scanning electron microscopy (FESEM) confirms that particle size reduces from 60 to 21�nm with increase of Fe concentration. The impedance analysis shows that highest electrical conductivity was 4.5 � 10�5 Scm?1 for Li2Fe0.4Mn0.6SiO4 cathode material. The initial specific capacity was 152 mAhg?1 at the rate of 0.1 C and 131 mAhg?1 after the 50th cycle with 86% capacity retention. The doping of Fe enhanced the conductivity by reducing its charge transfer resistance and increasing Li-ion diffusion coefficient than the pure Li2MnSiO4 cathode material. � 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.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.