School Of Basic And Applied Sciences
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Item Mesoporous carbon/titanium dioxide composite as an electrode for symmetric/asymmetric solid?state supercapacitors(Elsevier Ltd, 2022-08-27T00:00:00) Arya, Anil; Iqbal, Muzahir; Tanwar, Shweta; Sharma, Annu; Sharma, A.L.; Kumar, VijayThis paper reports the successful synthesis of mesoporous carbon/titanium dioxide (MC/TiO2) composite electrodes via the hydrothermal method for supercapacitor (SC) applications. The morphology and structural properties of MC/TiO2 composites were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectra (FTIR). The electrochemical properties were recorded by cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) with an electrolyte (6 M KOH) in symmetric/asymmetric configuration. The specific capacitance (Cs) evaluated by CV is about 280F/g for composite electrode (95 % capacitance retention after 1000 cycles) and pristine has 150F/g @ 10 mV/s. Enhancement in capacitance is owing to faster charge dynamics within electrode material. The fabricated asymmetric device demonstrates high energy density (30.31 Wh/kg), than the symmetric configuration (?27 Wh/kg). Finally, both symmetric/asymmetric supercapacitors have illuminated a red LED, and strengthens the candidature of composite electrode for energy storage technology. � 2022 Elsevier B.V.Item Nanofiller-assisted Na+-conducting polymer nanocomposite for ultracapacitor: structural, dielectric and electrochemical properties(Springer, 2021-01-04T00:00:00) Kamboj, Vashu; Arya, Anil; Tanwar, Shweta; Kumar, Vijay; Sharma, A.L.We report the preparation of ZrO2 nanofiller-incorporated polymer nanocomposite electrolyte based on the PEO-NaPF6 matrix via standard solution cast method. The structure and morphology of polymeric films have been examined with X-ray diffraction and field emission scanning electron microscopy. Different interactions between the polymer, salt and nanofiller have been examined by Fourier transform infrared technique. The temperature-dependent (40�100��C) electrical conductivity has been examined from complex impedance spectroscopy (CIS). The highest ionic conductivity is exhibited by 5�wt% nanofiller-based electrolyte and recorded ~ 2 � 10�4�S�cm?1 at 100��C. The voltage stability window of polymeric film checked from linear sweep voltammetry is about ~ 4�V, and ion transference number close to unity confirms the major contribution from ion conduction. The dielectric properties have been explored in terms of complex permittivity, loss tangent and complex conductivity. The dielectric plots have been further fitted with an associated equation to evaluate principal dielectric parameters. The optimized polymer electrolyte possesses the lowest relaxation time and the highest dielectric constant that suggests the highest ionic conductivity, which is in good correlation with impedance results. The dc conductivity is also highest for the optimum system, and relaxation time decreases with an increase in temperature. The thermal stability of polymer electrolytes is about 200��C, as examined by thermogravimetric analysis (TGA). The ion transport parameters n, ?, D have been evaluated via FTIR, impedance spectroscopy and Bandara and Mellander (B�M) approach. Finally, the optimized polymer nanocomposite film has been used as an electrolyte-cum-separator for the fabrication of a solid-state symmetric supercapacitor. The electrochemical parameters specific capacitance, energy density, power density have been examined from cyclic voltammetry and galvanostatic charge�discharge technique. It may be concluded that nanofiller incorporation is an effective strategy to enhance the properties of electrolyte and has the potential to adopt as an electrolyte-cum-separator for ultracapacitor. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.Item Coupling Nonstoichiometric Zn0.76Co0.24S with NiCo2S4Composite Nanoflowers for Efficient Synergistic Electrocatalytic Oxygen and Hydrogen Evolution Reactions(American Chemical Society, 2022-12-15T00:00:00) Biswas, Rathindranath; Thakur, Pooja; Ahmed, Imtiaz; Rom, Tanmay; Ali, Mir Sahidul; Patil, Ranjit A.; Kumar, Bhupender; Som, Shubham; Chopra, Deepak; Paul, Avijit Kumar; Ma, Yuan-Ron; Haldar, Krishna KantaTransition-metal sulfide-based composite nanomaterials have garnered extensive interest not only for their unique morphological architectures but also for exploring as a noble-metal-free cost-effective, durable, and highly stable catalyst for electrochemical water splitting. In this work, we synthesized in situ nonstoichiometric Zn0.76Co0.24S with NiCo2S4binary composite flowers (Zn0.76Co0.24S/NiCo2S4) in one step by thermal decomposition of Zn2[PDTC]4and Ni[PDTC]2complexes by a solvothermal process in a nonaqueous medium from their molecular precursor, and their potential application in electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was investigated. Field-emission scanning electron microscopy and transmission electron microscopy analyses revealed the flower-shaped morphology of as-synthesized Zn0.76Co0.24S/NiCo2S4. Again, the structural and chemical compositions were confirmed through powder X-ray diffraction and X-ray photoelectron spectroscopy studies, respectively. The as-obtained 3D flower-type Zn0.76Co0.24S/NiCo2S4nanostructure was further subject to electrochemical OER and HER in alkaline and acidic media, respectively. Zn0.76Co0.24S/NiCo2S4showed low overpotential values of 248 mV (Tafel slope, 85 mV dec-1) and 141 mV (Tafel slope, 79 mV dec-1) for OER and HER activities, respectively, due to the synergistic effects of Zn0.76Co0.24S and NiCo2S4. Several long-term stability tests also affirmed that the Zn0.76Co0.24S/NiCo2S4composite nanostructure is a highly stable and efficient electrocatalyst toward OER and HER activities as compared to the recently reported superior bifunctional electrocatalysts as well as state-of-the-art materials. � 2023 American Chemical Society. All rights reserved.Item Synthesis of in situ immobilized iron oxide nanoparticles (Fe3O4) on microcrystalline cellulose: Ecofriendly and recyclable catalyst for Michael addition(John Wiley and Sons Ltd, 2021-09-21T00:00:00) Kumar, Bhupender; Reddy, Marri Sameer; Dwivedi, Kartikey Dhar; Dahiya, Amarjeet; Babu, J. Nagendra; Chowhan, L. RajuMicrocrystalline cellulose-immobilized Fe3O4 magnetic nanoparticles (Fe3O4@MCC) with iron loading 5%�20% are synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The synthesized nanocomposites were studied for their catalytic activity towards Michael addition reaction by employing 1,3-cyclohexadione/dimedone and styrylisoxazole in an aqueous ethanolic medium. The catalyst with 15% iron loading showed the highest efficiency with an excellent yield. Michael addition reaction is one of the most important reaction for the creation of a carbon�carbon bond and widely used in organic synthesis under mild condition. The prepared catalyst performed well in Michael addition reaction and afforded the product in excellent yield. The products were isolated by simple filtration without use of any chromatographic techniques. The scale-up experiment on 10-mmol scale proved the sustainability of the methodology. The catalyst was recycled, and the recovered catalyst data showed no considerable depreciation in catalytic activity even after 5 consecutive cycles. The advantages of this green and safe procedure include a simple reaction set-up, very mild reaction conditions, high yields, moderate reaction time, recyclable catalyst, and easy separation of the products without use of any tedious separation techniques. � 2021 John Wiley & Sons, Ltd.Item Morpho-molecular assessment of Acetabularia jalakanyakae Sp. Nov. (Dasycladales, Chlorophyta) - a new species from Andaman and Nicobar Islands, India(National Institute of Science Communication and Policy Research, 2021-09-01T00:00:00) Saini, K.C.; Madhu, A.; Kohli, R.K.; Gupta, K.; Bast, F.Acetabularia (Dasycladales) is an extant genus of a single-celled green alga. There are four species of this genus reported from India, three reported from Andaman and Nicobar Islands. For this study, Acetabularia isolate was collected from a rocky intertidal habitat in the Andaman and Nicobar Islands. Light microscopy and Scanning Electron Microscopy were used for the morphological characterization. The distinct traits of caps of the thalli were prioritized because, traditionally, species delimitations in Acetabularia mainly were based on cap morphology. Our isolate showed morphological similarity with Acetabularia crenulata. However, the number of hairs in the inner ring of lobes of caps and the stalk length were observed to be different from A. crenulata and other closely related species. The phylogenetic tree constructed for partial 18S rDNA using the Maximum Likelihood (ML) method revealed the evolutionary affinity of this new species with Acetabularia dentata. Based on morphological and molecular synapomorphy, a new species of Acetabularia, Acetabularia jalakanyakae is formally proposed herein, and the further implications of this species discovery are discussed. � 2021 National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.Item Morpho-molecular assessment of Acetabularia jalakanyakae Sp. Nov. (Dasycladales, Chlorophyta) - a new species from Andaman and Nicobar Islands, India(National Institute of Science Communication and Policy Research, 2021-09-01T00:00:00) Saini, K.C.; Madhu, A.; Kohli, R.K.; Gupta, K.; Bast, F.Acetabularia (Dasycladales) is an extant genus of a single-celled green alga. There are four species of this genus reported from India, three reported from Andaman and Nicobar Islands. For this study, Acetabularia isolate was collected from a rocky intertidal habitat in the Andaman and Nicobar Islands. Light microscopy and Scanning Electron Microscopy were used for the morphological characterization. The distinct traits of caps of the thalli were prioritized because, traditionally, species delimitations in Acetabularia mainly were based on cap morphology. Our isolate showed morphological similarity with Acetabularia crenulata. However, the number of hairs in the inner ring of lobes of caps and the stalk length were observed to be different from A. crenulata and other closely related species. The phylogenetic tree constructed for partial 18S rDNA using the Maximum Likelihood (ML) method revealed the evolutionary affinity of this new species with Acetabularia dentata. Based on morphological and molecular synapomorphy, a new species of Acetabularia, Acetabularia jalakanyakae is formally proposed herein, and the further implications of this species discovery are discussed. � 2021 National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.