Browsing by Author "Nayak, M.P."

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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.
Pd/C-decorated SnO2 for advanced non-enzymatic cholesterol biosensing: analytical application in clinical blood specimens
(Elsevier Inc., 2025) Rao, L.; Rodney, J.D.; S, S.; Mascarenhas, F.J.; Nayak, M.P.; Kim, B.C.; Badekai Ramachandra, B.R.
Cholesterol, a critical biomolecule, plays a vital role in physiological functions; however, elevated levels are associated with chronic conditions such as cardiovascular diseases, which remain a leading cause of mortality globally. To address this challenge, this study presents the synthesis of SnO2-Pd/C nanocomposite through a two-step process as a promising material for non-enzymatic cholesterol biosensing. Initially, SnO2 was synthesized via a hydrothermal method and subsequently decorated with Pd/C. The resulting SnO2-Pd/C nanocomposite was integrated with nickel foam (NF) as the active material for biosensor development. The biosensor demonstrated a remarkable sensitivity of 1560 µA mM?1 cm?2 for cholesterol detection, which is approximately three times higher than that of SnO2-NF (546 µA mM?1 cm?2). Key performance metrics included a Limit of Detection (LOD) of 28 µM and a Limit of Quantification (LOQ) of 34 µM in 0.1 M KOH solution, with a linear detection range extending from 200 µM to 2 mM. The SnO2-Pd/C-NF biosensor exhibited outstanding cyclic stability, retaining 97 % of its performance over 30 days, underscoring its potential for reliable and long-term applications. Furthermore, the sensor demonstrated robust and consistent sensing performance with human serum samples under standard conditions, highlighting its practical applicability in clinical diagnostics. © 2025 Elsevier B.V.
Recycling waste plastics and biowaste into high-performance NiCo-MOF/activated carbon electrocatalyst for overall water splitting
(Elsevier Ltd, 2025) Nayak, M.P.; Rao, L.; Rodney, J.D.; S, S.; Rohit, A.G.; Badekai Ramachandra, B.R.
Environmental and energy crises are the most significant global challenges. Developing non-precious and environmentally sustainable electrocatalysts remains critical for advancing renewable hydrogen production. This study presents a novel hybrid electrocatalyst comprising a NiCo-BDC Metal-Organic Framework (NiCo-MOF), where the BDC (Benzene 1,4-di carboxylic acid) ligand was obtained by recycling waste poly(ethylene terephthalate) (PET) bottles, integrated with activated carbon (AC) derived from dried drumstick (Moringa olifera) biowaste, via a one-pot hydrothermal method. The research emphasizes optimizing the AC content within the MOF matrix to enhance catalytic performance. The synergistic interaction between NiCo-MOF and AC significantly reduces the overpotentials required for the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) in an alkaline medium. Notably, the optimized composite, NiCo-MOF@40AC, exhibited enhanced crystallinity, BET surface area, and electrocatalytic activity. At a current density of 100 mA cm?2, NiCo-MOF@40AC achieved overpotentials as low as 217 mV for HER with a Tafel slope of 105.6 mV dec?1 and 315 mV for OER with a Tafel slope of 42.2 mV dec?1. Furthermore, this material demonstrated robust stability over a 24 h chrono potentiometric test, maintaining performance at an elevated current density of 200 mA cm?2. In a two-electrode system, NiCo-MOF@40AC needed only 1.58 V to sustain a current density of 10 mA cm?2, exhibiting stability over 48 h and 24 h at a current density of 10 mA cm?2 and 400 mA cm?2, respectively. An average faradaic efficiency was found to be 93.48 % for HER and 91.91 % for OER. These findings highlight the potential of NiCo-MOF@40AC as an efficient electrocatalyst, characterized by a high surface area, rapid electron transfer, favorable structural properties, and enhanced reaction kinetics. © 2025 Hydrogen Energy Publications LLC