Faculty Publications
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Item Activated carbon derived from non-metallic printed circuit board waste for supercapacitor application(Elsevier Ltd, 2016) Rajagopal, R.R.; Aravinda, L.S.; Rajarao, R.; Badekai Ramachandra, B.R.; Sahajwalla, V.Activated carbons (ACs) have been synthesized by using waste PCBs via physical activation subsequent to pyrolysis processes. The physical and chemical properties of the produced activated carbons were studied using nitrogen adsorption, FT-IR spectroscopy, RAMAN spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy techniques. Among the synthesized ACs, AC with the highest surface area of 700 m2 g-1 produced at 850 °C for a time interval of 5 h was subjected to electrochemical studies. Capacitance behaviour of the obtained AC sample has been evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GC-D) measurements and electrochemical impedance spectroscopy (EIS) technique. Specific capacitance (Cspec) values vary from 220, 185 and 156 F g-1 for corresponding scan rate of 30, 50 and 100 mV s-1 respectively. The well-developed surface area properties and good capacitance values associated with nitrogen functionalities indicates the AC developed is a good and suitable candidate for the supercapacitor fabrication. © 2016 Elsevier Ltd.Item Properties of Mn3O4 thin film electrodes prepared using spray pyrolysis for supercapacitor application(Elsevier Ltd, 2023) Pramitha, A.; Hegde, S.S.; Badekai Ramachandra, B.R.; George, S.D.; Sudhakar, S.N.; Raviprakash, R.Film electrodes are made by depositing a thin layer of an electroactive material onto a conductive substrate. The performance of thin film electrodes in energy storage devices is significantly governed by their preparative conditions, particularly the molar concentration of the initial precursor. In the current study, the preparation of Mn3O4 thin film electrodes utilizing the chemical spray pyrolysis technique is discussed. The effect of molar concentration on the structural, morphological, and electrochemical properties of the thin film electrodes was thoroughly investigated using techniques including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) studies. Additionally, X-ray photoelectron spectroscopy (XPS) was employed to gain more insight into the oxidation states of the sample with the best electrochemical performance. Findings suggested that the molar concentration considerably affects the crystallite size, surface area, surface roughness, and wettability, which would directly impact the functionality of the electrode. It was concluded that the electrode deposited using the molar concentration of 0.06 M showed significantly improved performance according to the electrochemical measurements. The areal capacitance of up to 105.3 mF/cm2 in the aqueous electrolyte was recorded from CV measurements at a scan rate of 5 mVs−1. These electrodes could be an option for low-cost, environmentally friendly electrochemical capacitors if prepared under optimal deposition conditions. © 2023 Elsevier B.V.Item Biomass waste-derived porous graphitic carbon for high-performance supercapacitors(Elsevier Ltd, 2024) Hegde, S.S.; Badekai Ramachandra, B.R.Porous carbons possess considerable appeal and are in high demand as materials that can be produced from biomass waste. This study presents the transformation of Tectona grandis (Teak) sawdust into porous carbon materials, referred to as Tectona grandis sawdust-derived porous carbon (TPC), through a cost-effective FeCl3-assisted carbonization process, followed by a KOH activation. TPC samples were synthesized by carbonization at different temperatures (650–850 °C) and characterized comprehensively. Structural analysis via X-Ray diffraction (XRD), Raman, and Fourier Transform Infrared Spectroscopy (FTIR) revealed a progressive enhancement in graphitic structure and reduction of functional groups with increasing activation temperature. Field emission scanning electron microscopy (FESEM) displayed the development of intricate hollow tube-like porous networks in TPC-850, with the highest specific surface area (1767.66 m2/g) and pore volume (1.43 cm3/g). Electrochemical investigations showcased the superior performance of TPC-850 as a supercapacitor electrode due to its high graphitic nature, large surface area, and well-structured porosity. The galvanostatic charge-discharge (GCD) measurements exhibited a high specific capacitance of 572 F/g at 0.5 A/g in a 6 M KOH electrolyte. The high-frequency semicircle and low-frequency steeper region in electrochemical impedance spectroscopy (EIS) further indicated reduced resistance and enhanced ion diffusion in TPC-850. Significantly, TPC-850 demonstrated remarkable electrochemical cyclic stability, retaining 95.83 % of its initial capacity even after undergoing 4500 cycles at a scan rate of 500 mV/s. The findings underscore the viability of TPC-850 as a high-performance supercapacitor electrode material, providing insights into harnessing renewable resources for advanced energy solutions. This work highlights the potential of utilizing waste biomass for energy storage applications and demonstrates the feasibility of converting it into efficient porous carbon materials with substantial graphitization and porosity. © 2023 Elsevier LtdItem Enhancing supercapacitor performance with zinc doped MnSe nanomaterial(Springer, 2024) Mascarenhas, F.J.; Badekai Ramachandra, B.R.The decreasing availability of fossil fuels and the increasing demand for energy highlight the pressing need for sustainable energy sources. Electrochemical technologies, notably supercapacitors, play a key role. They promise renewable energy storage, necessitating high-performing, safe, and affordable electrode materials. In this study, we present a novel hydrothermal synthesis method for producing MnSe and ZnxMn1-xSe materials across a range of concentrations (x = 0.01, 0.02, and 0.03). Characterization techniques including XRD, FESEM, HRTEM, BET and Raman analysis were employed. Among the synthesized compositions, Zn0.03Mn0.97Se emerged as the most promising material for supercapacitor applications. Evaluation through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) revealed specific capacitance values of 135 F/g at 3 mV/s and 95 F/g at 0.5 A/g for Zn0.03Mn0.97Se. Furthermore, the material demonstrated impressive stability, retaining 97% of its capacitance after 1000 cycles. Additionally, to validate the potential of the synthesized electrode, we assembled a two-electrode symmetric cell using Zn0.03Mn0.97Se as both positive and negative electrode material in a 5 M KOH electrolyte. Extensive characterization techniques, including CV, GCD, and long-term cyclic stability tests, revealed compelling evidence of the material’s robust electrochemical behavior. These findings underscore the potential of Zn0.03Mn0.97Se for supercapacitors, contributing to the advancement of sustainable energy storage. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.Item Silver-doped zirconium copper oxide nanohybrid for electrochemical identification of dihydroxybenzene isomers(Springer Science and Business Media Deutschland GmbH, 2025) Achar, S.; Bhat, R.S.; Sajankila, S.P.; Badekai Ramachandra, B.R.The transition metal oxide (TMO) nanohybrids are the optimal electrode materials for the electrochemical recognition of the dihydroxybenzene isomers (DHBIs). The DHBIs includes mainly catechol (CA), hydroquinone (HY), and resorcinol (RE). In the current study, Ag-ZrCuO nanohybrid is synthesized by the efficient combustion method. The crystal structure of the synthesized nanohybrid is analyzed using X-ray diffraction (XRD) analysis. The morphological features and elemental compositions are investigated through field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis. The presence of different vibrational modes is studied by Raman spectroscopy. As synthesized Ag-ZrCuO nanohybrid is deposited on the glassy carbon electrode (GCE) and electropolymerized with L-valine, resulting in poly-valine-reduced graphene oxide-silver doped zirconium oxide/copper oxide nanohybrid-GCE (PV-rGO-Ag-ZrCuO-GCE). The fabricated electrode exhibits superior electrochemical redox activity compared to the bare GCE, as confirmed by electrochemical impedance spectroscopy (EIS) and Tafel plots. The modified electrode is implemented for the electrochemical recognition of DHBIs by employing linear sweep voltammetry (LSV), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) techniques. The PV-rGO-Ag-ZrCuO-GCE detects CA, HY, and RE, with a limit of detection (LOD) determined to be 0.026 µM, 0.005 µM, and 0.082 µM. The corresponding linear ranges were 0.2–3.4 µM, 0.3–5.5 µM, and 0.2–1.4 µM. In addition, the prepared electrode shows excellent response for commercially available samples and the ternary mixture of DHBIs. The fabricated electrode displays a high percentage of repeatability, reproducibility, stability, and selectivity for the electrochemical detection of DHBIs. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.Item Electrochemical determination of ascorbic acid using carbon paste electrode modified with cobalt oxide nanoparticles(Elsevier Ltd, 2025) G, B.A.; Bhat, R.S.; Hegde, S.S.; Badekai Ramachandra, B.R.The present work introduces a cobalt oxide nanoparticle-modified carbon paste electrode (Co2O3/CPE) as a simple, low-cost, and efficient platform for the electrochemical determination of ascorbic acid. This study shows the excellent selectivity of the electrode against common interferents, linear detection range, low detection limit, and reproducibility, making it a promising substitute to expensive noble-metal-based sensors for real-sample ascorbic acid analysis. An eco-friendly novel electrochemical study is carried out to detect ascorbic acid (ACA) using a Congo red (CR) modified cobalt oxide nanoparticle (Co3O4) composite carbon paste electrode (CRMCCCPE). This CRMCCCPE significantly enhanced the electrochemical performance for the selective and sensitive analysis of ACA. The elemental analysis of the synthesised Co3O4 by EDX (energy-dispersive X-ray spectroscopy), the phase structure through XRD (X-ray diffraction), and the absorbance peaks by Raman spectrometry with 37.41 nm. The surface topography by FESEM (field emission scanning electron microscopy). Voltammetric techniques and EIS (electrochemical impedance spectroscopy) are investigated for the electrochemical redox response of ACA in phosphate buffer (PB) of 0.1 M concentration across the various ranges of pH at a 0.1 V/s scan rate. The ACA detection through the impact of pH, impact of scan rate, concentration, interference, simultaneous detection, and real sample analysis, indicating CV at 0.2 ?M to 2.4?M, DPV at 0.2 ?M to 2.6?M and LSV at 0.2 ?M to 2.4?M, with a lower limit of detection (LOD) were CV is 1.4 ??, DPV is 0.7 ?M, and LSV is 1.5 µ? and quantification (LOQ) was CV is 4.8 ?M, DPV is 2.6 µM, and LSV is 5.0 ?M. The fabricated CRMCCCPE exhibits the novelty of excellent stability, reproducibility, and repeatability, suggesting its potential application for the electrochemical recognition of ACA in complex matrices. The results indicate that CRMCCCPE is a reliable and effective platform for voltammetric sensing of ACA, offering promising applications in food quality control and medicinal diagnostics. © 2025 Elsevier Ltd.