Faculty Publications
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Item Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2(Institute of Physics Publishing michael.roberts@iop.org, 2016) Aravinda, L.S.; Nagaraja, K.K.; Nagaraja, H.S.; Bhat, K.U.; Badekai Ramachandra, B.R.We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg-1 in two-electrode configuration. © 2016 IOP Publishing 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 Sustainable energy storage: Mangifera indica leaf waste-derived activated carbon for long-life, high-performance supercapacitors(Royal Society of Chemistry, 2024) Hegde, S.S.; Badekai Ramachandra, B.R.Biomass waste-derived activated carbon has a wide range of applications, including air and water purification, gas separation, energy storage, and catalysis. This material has become increasingly popular in recent years as a result of the growing demand for sustainable and eco-friendly materials. In this study, Mangifera indica leaf waste-derived activated carbon has been investigated as an electrode material for high-performance supercapacitors. The dried Mangifera indica leaves were first carbonized using FeCl3 and then activated using KOH to increase their surface area and pore structure at different temperatures. The activated carbon prepared at 725 °C has shown a high specific capacitance of 521.65 F g−1 at a current density of 0.5 A g−1 and also achieved an energy density of 17.04 W h kg−1 at a power density of 242.50 W kg−1 in the 6 M KOH electrolyte. Significantly, it has demonstrated remarkable electrochemical cycling stability, retaining 96.60% of its initial capacity even after undergoing 10 001 cycles at a scan rate of 500 mV s−1. The superior electrochemical performance of the activated carbon can be attributed to its high surface area of 1232.63 m2 g−1, well-distributed pore size, and excellent degree of graphitization, which all facilitate the rapid diffusion of ions and enhance the accessibility of the electrolyte to the electrode surface. Hence, this study provides a promising route for utilizing waste biomass as a low-cost, sustainable electrode material for energy storage devices. © 2024 The Royal Society of Chemistry.Item Significance of transition metal (Co, Ni and Zn) doping on the nano MnSe for high-performance supercapacitor electrode(Elsevier Ltd, 2024) Mascarenhas, F.J.; Rodney, J.D.; Kim, B.C.; Badekai Ramachandra, B.R.The demand for electrode materials in supercapacitors necessitates designs with exceptional performance, superior structure, and environmental sustainability, all while remaining affordable and abundantly available. This study introduces an economical hydrothermal synthesis method for producing MxMn1-xSe (M=Co / Ni / Zn) nanomaterials at varying concentrations (x = 0.0, 0.01, 0.02, and 0.03). Diverse characterization methods confirm the successful formation of nanomaterials. Among the materials studied, Co0.01Mn0.99Se nanoclusters exhibit superior performance as electrode materials for supercapacitors, delivering a specific capacitance of 421 F/g at 5 mV/s and 377 F/g at 1 A/g in a 5 M KOH solution. A two-electrode symmetric configuration was established utilizing Co0.01Mn0.99Se as the active material in a 5 M KOH electrolyte, yielding a notable specific capacitance of 73 F/g at 0.5 A/g. The maximum energy density and power density achieved are 20.44 Wh/kg and 2838 W/kg respectively. This configuration demonstrates the exceptional electrochemical performance and energy storage capabilities of Co0.01Mn0.99Se in a two-electrode system. Impressively, the symmetric cell maintains a significant 70% capacitance retention even after 5000 charge-discharge cycles. Considering these findings, the developed Co0.01Mn0.99Se emerges as a pivotal advancement, providing a robust framework for the development of cutting-edge energy conversion and storage technologies. © 2024 Elsevier B.V.Item Unveiling the mass-loading effect on the electrochemical performance of Mn3O4 thin film electrodes: a combined computational and experimental study(Institute of Physics, 2024) Pramitha, A.; Hegde, S.S.; Badekai Ramachandra, B.R.; Yadav K, C.; Chakraborty, S.; Ravikumar, A.; George, S.D.; Sudhakar, Y.N.; Raviprakash, Y.The remarkable storage performance of manganese oxide (Mn3O4) makes it an appealing option for use as electrodes in electrochemical capacitors. However, the storage kinetics were significantly influenced by the mass loading of the electrode. Herein, we have inspected the dependency of mass loading on the storage performance of the spray pyrolyzed Mn3O4 thin film electrodes along with the correlation of structural and morphological characteristics. X-ray diffraction and Raman spectroscopic studies proven the formation of spinel Mn3O4 with a tetragonal structure. Morphological analysis revealed that all films exhibited fibrous structures with interconnected patterns at higher mass loadings. Moreover, the surface roughness and wettability of the electrode surface were influenced by variations in mass loading. Notably, thin-film electrode with a mass loading of 0.4 mg cm?2 exhibited the highest specific capacitance value of 168 F g?1 at 5 mV s?1 in a three-electrode system. Further, electrochemical impedance spectroscopic studies showed that there were noticeable changes in the capacitive behaviour of the electrode with respect to variations in mass loading. Moreover, the Dunn approach was employed to differentiate the underlying storage mechanism of the Mn3O4 electrode. Additionally, first-principles Density Functional Theory (DFT) studies were carried out in connection with the experimental study to comprehend the structure and electronic band structure of Mn3O4. This study underscores the critical importance of mass loading for enhancing the storage performance of Mn3O4 thin-film electrodes. © 2024 The Author(s). Published by IOP Publishing Ltd.Item Electrochemical insights into manganese-cobalt doped ?-Fe2O3 nanomaterial for cholesterol detection: a comparative approach(Royal Society of Chemistry, 2025) Sushmitha, S.; Ray, S.; Rao, L.; Nayak, M.P.; Carva, K.; Badekai Ramachandra, B.R.Herein, a self-assembled hierarchical structure of hematite (?-Fe2O3) was synthesized via a one-pot hydrothermal method. Subsequently, the nanomaterial was doped to obtain MxFe2?xO3 (M = Mn-Co; x = 0.01, 0.05, and 0.1) at precise concentrations. An electrode was fabricated by coating the resulting nanocomposite onto a nickel foam (NF) substrate. Electrochemical characterization demonstrated the excellent performance of cobalt-doped ?-Fe2O3, among which Co0.05Fe0.95O3 (CF5) exhibited a superior performance, showing a two-fold increase in sensitivity of 1364.2 ?A mM?1 cm?2 (±0.03, n = 3) in 0.5 M KOH, a limit of detection (LOD) of ?0.17 mM, and a limit of quantification (LOQ) of ?0.58 mM. The Density Functional Theory (DFT) was performed to understand the doping prompting in the reduced bandgap. The fabricated electrode displayed a rapid response time of 2 s and demonstrated 95% stability, excellent reproducibility, and selectivity, as confirmed by tests with several interfering species. A comprehensive evaluation of the electrode's performance using human blood serum highlighted its robustness and reliability for cholesterol detection in clinical settings, making it a promising tool for clinical and pharmaceutical applications. © 2025 The Royal Society of Chemistry.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.