Green synthesis and characterization of bimetallic Ni(OH)2-Ag/AgCl electrocatalysts for the oxygen reduction reaction

Abstract This study reports a novel green synthesis of carbon-supported β-Ni(OH) 2 -Ag/AgCl electrocatalysts, using for the first time a Sargassum spp. extract as a stabilizing agent in a hydrothermal method. Physicochemical characterization by FT-IR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy), and Raman confirmed the formation of a heterostructure composed of nanosheets decorated with Ag/AgCl nanoparticles and capped by organic remains. The optimized catalyst exhibited exceptional Oxygen Reduction Reaction (ORR) activity in alkaline media, achieving a half-wave potential of 0.880 V ( vs. RHE), surpassing the commercial Pt/C benchmark by 78 mV. Kinetic analysis via the Koutecky–Levich equation confirmed a preferred four-electron pathway. Furthermore, the composite demonstrated superior operational durability compared to the platinum standard. This synergistic performance positions this bio-derived material as a robust, low-cost alternative for energy conversion technologies. Graphical abstract