Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
10 results
Search Results
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 Utilization of newly configured carbazole-cyanopyridone structural hybrids towards achieving high-performance cyan fluorescent organic light-emitting diodes(Royal Society of Chemistry, 2024) Vishrutha, K.S.; Ulla, H.; Raveendra Kiran, M.; Badekai Ramachandra, B.R.; Vasudeva Adhikari, A.V.Herein, we report the synthesis, characterization, and device fabrication of novel D-A-D (donor-acceptor-donor) type cyanopyridone-based cyan light-emitting organic materials. These small molecules feature a strong electron-donating N-alkylated carbazole unit affixed to a powerful electron-withdrawing cyanopyridone core that is appended with varying secondary donor groups, producing bipolarity in their structures. All the synthesized molecules were well characterized by employing FT-IR, 1H NMR, and 13C NMR spectroscopy, followed by in-depth photophysical, thermal, electrochemical, and electroluminescent studies. Furthermore, we used the density functional theory (DFT) computational approach in the theoretical investigations to gain deeper insights into their electron cloud distributions and structural features. These fluorophores exhibit emission in the 489-510 nm range accompanied by high Stokes shift values, and their TGA data validate the excellent thermal stability (384 °C). As estimated by cyclic voltammetry, the HOMO and LUMO energy levels were found to be 5.35-5.69 eV and 2.92-3.02 eV, respectively, with band gaps of 2.36-2.74 eV. The optical and electrochemical properties of the luminogens have been successfully fine-tuned by varying the auxiliary donors at the carbazole-cyanopyridine hybrids. Electroluminescent studies proved the compatibility of the novel compounds to be an efficient cyan emissive layer with good performance characteristics. Interestingly, amongst the luminophores, Cz-CyP5 bearing a 4-hydroxyphenyl moiety exhibited a maximum current efficiency of 13.16 cd A−1, high power efficiency of 9.85 lm W−1, and good external quantum efficiency of 5.41%. © 2024 RSC.Item 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 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 Growth of octahedral structured AgBiS2 single crystals and its insights on the high performance electrocatalytic hydrogen generation(Elsevier Ltd, 2024) Jauhar, R.O.M.; Ramachandran, K.; Deepapriya, S.; Joshi, S.; Ghfar, A.A.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.; Vadivel, V.; Raji, R.; Kim, B.C.; Rodney, J.D.Given the enormous depletion of fossil fuels and growing environmental concerns, there is an immediate need to develop alternative and clean energy sources. Hydrogen (H2), recognized for its cleanliness and renewability, is poised to meet future energy requirements. Consequently, ongoing research is focused on the development of electro-active, durable, and cost-effective catalysts to replace expensive noble metal-based electrocatalysts. In this study, microscale AgBiS2 chalcogenide derived from a single crystal is reported as promising electrocatalysts for the Hydrogen Evolution Reaction (HER) with a remarkably low overpotential. The physico-chemical characterization of the AgBiS2 catalyst has been investigated using various analytical techniques. The synthesized AgBiS2 catalyst exhibits excellent HER activity, manifesting a low overpotential of 86 mV at a current density of 10 mA cm−2 and a Tafel slope of 44 mV dec−1, along with superior stability even after 24 h in HER at a very high current density. The developed AgBiS2 also showcased stable production when subjected to a two-electrode system. The enhanced alkaline HER activity of AgBiS2 can be attributed to its phase purity, high crystallinity, and the presence of high active sites. The observed high electrochemical performance and stability position AgBiS2 as a potential electrocatalyst for the hydrogen evolution reaction. This finding holds significant promise in the quest for efficient, durable, and economically viable catalysts to drive the shift towards clean and renewable energy sources. © 2024 Hydrogen Energy Publications LLCItem Impact of electrolyte concentration on electrochemical performance of Cocos nucifera Waste-Derived High-Surface carbon for green energy storage(Elsevier Ltd, 2024) Hegde, S.S.; Badekai Ramachandra, B.R.The increasing popularity of utilizing biomass's natural structure represents a promising avenue for sustainable innovation, as it taps into the inherent characteristics of organic materials to address various environmental and industrial challenges. Researchers and industries continue to explore the full potential of biomass in creating more sustainable and efficient solutions. The transformation of biomass into carbon materials is an indirect means of utilizing CO2 as a carbon source, thus contributing to the sustainable development of energy storage technologies and also in pollution reduction. In the quest for sustainable energy solutions, this research unveils a cost-effective approach to supercapacitor development by harnessing the untapped potential of Cocos nucifera trunk sawdust-derived high-surface carbon (CHSC). Through a meticulous process involving ZnCl2 treatment and KOH activation at varying temperatures, CHSC-700 emerges as a standout electrode material with exceptional structural characteristics, boasting enhanced graphitization and a specific surface area of 1153.72 m2/g. Further, the study delved into the nuanced relationship between electrolyte concentration and supercapacitor performance, pinpointing 6 M KOH as the optimal condition. In 6 M KOH, the electrode exhibits a maximum specific capacitance of 559.27F/g at the current density of 0.5 A/g with outstanding cyclic stability, retaining 80.37 % capacitance after 20,000 cycles and an impressive energy density of 18.92 Wh/kg and power density of 246.75 W/kg. This systematic exploration provides valuable data for understanding the biomass-derived carbon electrode's behaviour under various electrolyte concentrations, offering crucial information for optimizing its performance in practical applications, such as energy storage devices. © 2024 Elsevier LtdItem Cerium-Modulated Zinc Oxide for enhanced Photoelectrochemical Non-Enzymatic biosensing of Cholesterol: An experimental and First Principle Analysis(Elsevier B.V., 2024) Rao, L.; Rodney, J.D.; Joy, A.; Shivangi Nileshbhai, C.; James, A.; S, S.; Joyline Mascarenhas, F.; Udayashankar, N.K.; Anjukandi, P.; Chul Kim, B.; Badekai Ramachandra, B.R.Herein, we synthesized CexZn1-xO (x = 0.00, 0.01, 0.02, and 0.03) using the wet chemical method. The investigation explores photoelectrochemical (PEC) biosensors for enzyme-free detection of cholesterol, employing Ce0.03Zn0.97O (CZO3)/Nickel Foam (NF) as the active material. The investigation revealed notable enhancements in sensitivity for cholesterol detection, with a recorded activity of 2.812 mA.mM?1.cm?2, marking a twofold increase in comparison to dark mode (1.37 mA.mM?1.cm?2). The Limit of Detection (LOD) was determined to be 17 µM (light) and 28 µM (dark), while the Limit of Quantification (LOQ) was measured at 54 µM (light) and 98 µM (dark) in 0.1 M KOH solution. These findings demonstrate a linear detection range spanning from 80 µM to 2 mM. Ab-initio calculations based on Density Functional Theory (DFT) were carried out on 101 surfaces of both pristine ZnO and CZO3 to understand how the doping affected the pristine ZnO band gap. The findings indicate that CZO3 exhibits superior activity compared to pristine ZnO, underscoring its enhanced performance and potential for sensing application. The CZO3/NF photoelectrochemical (PEC) biosensor displayed notable cyclic stability, retaining 97 % of its performance over a 60-day period. This underscores its potential for reliable and enduring operation in biosensing applications. Additionally, CZO3/NF exhibited robust sensing capabilities when utilized with human serum samples, showcasing consistent performance in both dark and illuminated conditions. © 2024 Elsevier B.V.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.