Department Of Physics
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Item Economic and environment friendly carbon decorated electrode for efficient energy storage devices(Elsevier Ltd, 2023-04-26T00:00:00) Singh, Nirbhay; Tanwar, Shweta; Sharma, A.L.; Yadav, B.C.The most dependent storage technologies are secondary batteries and supercapacitors. Supercapacitors are more competent regarding faster energy supply, sustainability, and high-capacity retaining. However, in supercapacitors, most research comprises the least abundant materials that raise the cost and toxicity, which are unfavorable to the environment. Therefore, we have prepared activated carbon-based earth-abundant iron oxyhydroxide material via a low-temperature hydrothermal technique. The key finding of this research is sustainable materials, with co-related studies of TEM and GCD cyclic stability (pre and post-cycling characterizations up to 10k). The X-ray photoelectron spectroscopy analysis reveals the elemental composition of the optimized sample. The electrochemical performance has been tested via galvanostatic charge-discharge analysis, electrochemical impedance spectroscopy, and cyclic voltammetry. The cyclic stability evaluation is done to see the lasting usability of the device for the 10,000th number of charging-discharging cycles, which is supported by electrochemical impedance spectroscopy results in form of a Nyquist plot. The galvanostatic charge-discharge analysis revealed the specific capacitance of 372 F g?1 at 2 mA. The specific energy and power density were obtained as 40 Wh kg?1 and 4200 W kg?1, respectively. The ACF1 shows Coulombic efficiency and capacity retention as 96 % and 80 %, respectively, up to 10k cycles. We have proposed a charge storage mechanism for the fabricated electrode. A supercapacitor has been made-up and tested for the glow of LED, and the device can glow LED for 20 min. The device was repeated after two months and reproduced the LED glow for the same duration. � 2023 Elsevier LtdItem High-performance symmetric supercapacitor based on activated carbon-decorated nickel diselenide nanospheres(Springer, 2022-11-11T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.The vital challenge is to advance the electronic conductivity of the transition metal diselenide for their supercapacitor application. In this report, nickel diselenide nanospheres and their decoration by activated carbon are reported by a one-step, surfactant-free hydrothermal technique. The activated carbon-decorated NiSe2 nanospheres (NAC) electrode displays high electrochemical performance than pure NiSe2 nanospheres due to more active sites, enhanced conductivity, and reduced diffusion path of electrons and electrolyte ions for maximum energy storage. The NAC electrode depicts a specific capacity of about 119 C g?1 at 0.3 A g?1. The fabricated symmetric supercapacitor using an NAC electrode shows a high specific capacitance of about 282 F g?1 at 10�mV�s?1. The cycle stability of 70% for ten thousand cycles is exhibited for the fabricated symmetric supercapacitor. It manifests high specific energy of 28�W�h�kg?1 and specific power of value 980�W�kg?1 at 1 A g?1. Device applicability with load is tested at laboratory scale by glowing different color LEDs, and a panel of 26 red LEDs illuminated for 56�min effortlessly. A self-explanatory mechanism has also been proposed to make it easier to realize the readers about glowing LEDs, and their panels. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item High-performance different shape carbon decorated asteroidea-like cobalt diselenide electrode for energy storage device(Elsevier Ltd, 2022-08-18T00:00:00) Tanwar, Shweta; Singh, Nirbhay; Sharma, A.L.Presently, the selenides-based transition metal appears to be one of the encouraging materials utilized in energy conservation, and storage applications. In this report, we presented the pure cobalt diselenide (CoSe2) and its composite with different shaped carbon using the one-step hydrothermal method. The CoSe2 with activated carbon composite exhibited the highest electrochemical performance among all prepared samples. It depicts retention of capacitance at around 80 % for 5000 cycles. A symmetric device prototype cell has been designed using a CoSe2/activated carbon composite electrode which displays the highest specific energy and power density as 83 Wh kg?1 at 1622 W kg?1. The maximum specific capacitance displayed by it is 886 F g?1 for a constant 10 mV s?1 Further, a possible charge storage mechanism related to the fabricated cell is proposed. The fabricated device application in practical life has been tested via a glowing panel containing 17 light-emitting diodes (LEDs) and its performance remains the same after six months too. The noteworthy improved capacity, good cycling stability, and high specific energy for the CoSe2 with activated carbon composite material is possibly considered a potential candidate for energy storage devices, and portable electronics. � 2022 Elsevier LtdItem 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 Ltd