Phyto-Assisted Synthesis of Co3O4 and NiCo₂O₄ Nanoparticles Using an Ethanolic Extract of Sargassum sp. for Oxygen Evolution Electrocatalysis

The increasing demand for clean and renewable energy sources to replace fossil fuels has driven the search for sustainable alternatives, among which green hydrogen stands out. Its production via water electrolysis requires efficient, stable, and sustainable electrocatalysts for the oxygen evolution reaction (OER). This work presents the bio-assisted synthesis of Co₃O₄ and NiCo₂O₄ nanoparticles using an ethanolic extract of Sargassum sp. Structural and morphological characterization by XRD, FTIR, Raman spectroscopy, SEM, and EDS confirmed the successful formation of spinel oxides with well-defined elemental composition. Both materials exhibited promising OER performance in alkaline medium, achieving overpotentials of 382 and 385 mV at 10 mA cm⁻² and Tafel slopes of 68.0 and 69.8 mV dec⁻¹ for Co₃O₄ and NiCo₂O₄, respectively. These results demonstrate the potential of marine biomass as a sustainable resource for the production of efficient electrocatalysts for green hydrogen production.