Faculty Publications
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Publications by NITK Faculty
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Item Enhanced Power Density of Graphene Oxide–Phosphotetradecavanadate Nanohybrid for Supercapacitor Electrode(Springer, 2021) Maity, S.; Anandan Vannathan, A.A.; Kumar, K.; Das, P.P.; Mal, S.S.Successful exploration of supercapacitor (SC) material to integrate with high energy and high power density storage device still remains a daunting challenge. Conducting carbon nanostructures have been primarily used for this purpose; however, most of their surface area remains unutilized throughout the storage process. Herein, a new type of hybrid material has been reported by effectively using active sides of carbon nanostructures. Insertion of faradaic-type polyoxometalates (POMs), namely phosphotetradecavanadate (Na7[H2PV14O42], hereafter described as PV14), into the graphene oxide (GO) matrix creates a novel hybrid material for SC applications. Owing to the formation of nanohybrid, it can store charges both electrostatically and electrochemically. PV14/GO composite’s electrochemical behavior in different electrolyte (acidic/neutral) solutions shows different types of characteristics. The PV14/GO composite as a working electrode exhibits a high galvanostatic capacitance of 139 F/g while maintaining at a power density of 97.94 W/kg in 0.25 M H2SO4 electrolyte. The specific energy density was also found out to be around 56.58 Wh/kg at a 5 mV/s scan rate for the same electrolyte. Furthermore, in 1 M Na2SO4 solution, PV14/GO composite demonstrates a specific capacitance of 85.4 F/g at a scan rate of 5 mV/s. The equivalent series resistance for the device was found to be approximately 0.51 ? with a circuit resistance of 3.881 ?, using electrochemical impedance spectroscopy. The cell capacitance, employing the Nyquist plot, was calculated to be around 2.78 mF. © 2021, ASM International.Item Understanding Solidification Behavior of Salt Phase Change Material with Added Carbon Nanoparticles Using Computer-Aided Cooling Curve Analysis(Springer, 2022) R, S.; K.n, P.In recent years, nanoparticle-dispersed salt-based phase change materials (PCMs) have emerged to be suitable for thermal energy storage applications. In this work, the carbon nanostructures of graphite, multiwall carbon nanotube (MWCNT) and graphene were separately dispersed in potassium nitrate. Solidification of these nanosalt-PCMs was analyzed using a computer-aided cooling curve analysis technique. The technique is much more effective in comparison with other alternatives such as differential scanning calorimetry, as it is simple and low cost and employs large sample sizes. In the present study, PCM sample size of 1kg was fixed with nanoparticle concentration varying from 0.1 to 0.5% by weight of the sample. The solidification time of the PCM was observed to decrease significantly on addition of nanoparticles indicating an enhancement in the heat removal rate. It is beneficial as the same amount of stored thermal energy can then be withdrawn at a much higher rate. Graphite and MWCNT additions decreased the thermal diffusivity property of the base PCM, while the graphene additions resulted in higher thermal diffusivity. However, the benefits of addition of nanoparticles to the salt-PCM reduced on thermal cycling. SEM images show that the deterioration in the observed enhancements occurred due to agglomeration of nanoparticles. This was observed in the initial 3-4 thermal cycles, and the nanosalt-PCM remained stable thereafter. The PCM developed here offers higher heat transfer rates with superior energy density. © 2021, ASM International.