Rational design of nickel-based nanostructured catalysts for enhanced electrolytic water splitting efficiency and stability

Rational design of cost-effective and highly stable oxygen evolution reaction (OER) electrocatalysts represents a pivotal challenge for advancing efficient water electrolysis toward hydrogen production. In this study, we propose a novel approach of mechanochemical ball-milling followed by calcination to construct mica-supported nickel oxide (NiO/mica) composites. Metallic Ni nanoparticles were uniformly anchored on muscovite mica through high-energy ball-milling, followed by controlled oxidation at 600 °C for 4 h under an air atmosphere. The resultant catalyst exhibits a distinctive hierarchical lamellar-flake architecture. Electrochemical measurements in 1 M KOH electrolyte demonstrate superior OER performance, requiring an overpotential of only 270 mV to achieve a current density of 10 mA cm^-2, outperforming commercial RuO₂ benchmarks (295 mV). The favorable reaction kinetics are further corroborated by a Tafel slope (51.2 mV dec^-1). Remarkably, the catalyst maintains stable operation for 390 h in alkaline media without significant potential elevation. This work proposes an innovative strategy for developing composite electrocatalysts that can synergistically combine economic viability with excellent durability, providing new insights into the scalable catalyst engineering for sustainable hydrogen generation.