Green Synthesis of NiO Nanoparticles Using Waste Tea Extract and Their Utilization as Potential Electroanode for Ethanol Oxidation

This study presents a novel approach, aimed at developing sustainable energy material. Green synthesis of nickel oxide nanoparticles (NiO NPs) is done using waste tea extract. The as‐synthesized NiO NPs are tested for electro‐oxidation of ethanol, demonstrating a notable reduction in overpotential at 0.44 V (in 1 M KOH + 1 M ethanol) from 0.67 V (in 1 M KOH) at a current density of 10 mA cm −2 . Comparative analysis with a benchmark platinum‐based electrocatalyst reveals that the green NiO‐NPs exhibited superior intrinsic kinetics and mechanistic performance, with a lower Tafel slope of 102 mV dec −1 and charge transfer resistance of 26 Ω. These results underline the efficiency and economic viability of using a bioinspired method for synthesizing NiO NPs, while also stressing the potential for upcycling waste tea. This innovative approach offers significant implications for the development of ecofriendly and sustainable energy conversion technologies.