School Of Basic And Applied Sciences
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Item All-redox hybrid supercapacitors based on carbon modified stacked zinc cobaltite nanosheets(Royal Society of Chemistry, 2023-09-12T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.The role of energy in the present century has increased with the fast advancement of the global economy. In this regard, hybrid supercapacitors (HSCs) as energy storage systems have become an extensive research focus worldwide. This study reports the synthesis of carbon-loaded ZnCo2O4 stacked nanosheets via an in situ hydrothermal process followed by annealing. The electrochemical response was tested in a 2-electrode system. The optimized composite exhibited a capacitance of ?527.6 F g?1 at 5 mV s?1. The symmetric SC (SSC) possessed an energy density (Ed) of ?17.3 W h kg?1 corresponding to a power density (Pd) of 2.25 kW kg?1. Two asymmetric all-redox HSCs have also been fabricated using an optimized composite material as the positive electrode. The previously synthesized MnCo2O4/AC (HSC1) and MnO2/AC (HSC2) were taken as negative electrodes. HSC1 exhibited an Ed of ?24.4 W h kg?1 corresponding to a Pd of ?0.8 kW kg?1. On the other hand, HSC2 exhibited the highest Ed of ?30.8 W h kg?1 at 2.4 kW kg?1. The real-time application of the composite is tested with the fabricated HSCs. HSC1 exhibited a capacitive retention of ?72.2% after 10 000 cycles. On the other hand, HSC2 exhibited a capacitive retention of ?73.4% after 10 000 cycles. The SSC, HSC1, and HSC2 illuminated a 39 red LED panel for ?3 min, 7 min, and 13 min, respectively. The results suggested the promising performance of all-redox HSCs. The overall results present a sustainable approach for creating hierarchical energy materials for the construction of future energy-storage systems. � 2023 The Royal Society of Chemistry.Item Self-assembled carbon wrapped manganese cobaltite nano-composite with promising electrochemical performance for symmetric and asymmetric supercapacitor device(Elsevier Ltd, 2023-05-27T00:00:00) Kour, Simran; Kour, Pawanpreet; Sharma, A.L.The growing energy requirements of modern society have led to an intensive search for advanced supercapacitor (SC) electrode materials. Binary transition metal oxides with excellent supercapacitive performance are among the most promising materials. However, the phase transformation of these metal oxides during repeated charging/discharging is a major concern, which depletes their cyclic performance. Coating metal oxides with carbon can provide structural stability to the metal oxide, thereby increasing their cyclic life. In addition, the highly conductive carbon enhances the capacitance of metal oxides by allowing the effective transfer of charges from MnCo2O4 to the current collector. In this study, self-assembled carbon-wrapped MnCo2O4 composite has been prepared through a two-step process involving hydrothermal and solution-mixing processes. The structural/electrochemical performances of the composites have been investigated. The optimized composite offered a maximum capacitance of 626.8 Fg?1 withholding 98 % of capacitance for 6000 cycles. Furthermore, the electrochemical performance of the composite has also been tested in an all-redox symmetric SC (SSC) as well asymmetric (ASC) configuration. In the symmetric cell, 30.2 Whkg?1 of energy is reported for 1.6 kWkg?1 of power. The asymmetric cell with the optimized composite as a cathode and MnO2/Activated carbon as an anode was fabricated. The ASC displayed 45.5 Whkg?1 of energy corresponding to 10 kWkg?1. Three SSCs/ASCs in series illuminated a panel of 39 red-LEDs for 9 and 15 min, respectively. The results suggest the promising performance of such composites for hybrid supercapacitors. Thus, the fabrication of all-redox-type SSCs/ASCs can be a futuristic approach for hybrid storage systems. � 2023 Elsevier LtdItem Aging impact on morphological and electrochemical performance of MoSe2 composite for supercapacitor application(Elsevier Ltd, 2023-02-27T00:00:00) Tanwar, Shweta; Sharma, A.L.The report is associated with the investigation of the impact of selenium powder aging in hydrazine hydrate acting as a reducing agent on the electrochemical performance of the molybdenum diselenide/activated carbon (MoSe2@AC) composite-based electrodes, and its supercapacitor application. The MoSe2@AC composite is formulated via the simple hydrothermal method. The composite formation is validated via structural, chemical bond, and morphology investigation. Among all synthesized samples, six days aged sample coded M6AC appears to exhibit the best electrochemical performance. The specific capacitance estimated for M6AC material-based fabricated symmetric cell is around 394 F g?1 at the 1 A g?1 using KOH (6 M) electrolyte. The energy and power density delivered by the same cell at 1 A g?1 is about 55 W h kg?1 and 845 W kg?1 correspondingly. Furthermore, we have tested the real-world usability of the M6AC symmetric cell by illuminating different voltage cum colors light emitting diodes (LEDs). The 26 red LEDs in the parallel connection illuminate for approximately 32 min with the aid of our fabricated symmetric cell as the power source. For easy understanding of the readers, we also report the self-proposed charge storage mechanism linked with the glowing LEDs using our obtained experimental results. Thereby, the observed outcomes associated with the M6AC material indicate that it has immense potential for scaling its performance at the industrial cum commercial level to resolve the energy crisis problem of the society. � 2023Item 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 Maps for when the living gets tough: Maneuvering through a hostile energy landscape(Elsevier B.V., 2016) Mondeel, T.D.G.A.; Rehman, S.; Zhang, Y.; Verma, M.; D?rre, P.; Barberis, M.; Westerhoff, H.V.With genome sequencing of thousands of organisms, a scaffold has become available for data integration: molecular information can now be organized by attaching it to the genes and their gene-expression products. It is however, the genome that is selfish not the gene, making it necessary to organize the information into maps that enable functional interpretation of the fitness of the genome. Using flux balance analysis one can calculate the theoretical capabilities of the living organism. Here we examine whether according to this genome organized information, organisms such as the ones present when life on Earth began, are able to assimilate the Gibbs energy and carbon that life needs for its reproduction and maintenance, from a relatively poor Gibbs-energy environment. We shall address how Clostridium ljungdahlii may use at least two special features and one special pathway to this end: gear-shifting, electron bifurcation and the Wood-Ljungdahl pathway. Additionally, we examined whether the C. ljungdahlii map can also help solve the problem of waste management. We find that there is a definite effect of the choices of redox equivalents in the Wood-Ljungdahl pathway and the hydrogenase on the yield of interesting products like hydroxybutyrate. We provide a drawing of a subset of the metabolic network that may be utilized to project flux distributions onto by the community in future works. Furthermore, we make all the code leading to the results discussed here publicly available for the benefit of future work. ? 2017