Plasma-Engraved IrO_<i>x</i> ontoNi(OH)₂ Nanosheets for Catalytic Hydrogen Evolution Reaction

The performance of transition metal hydroxide, as a promising cost-effective electrocatalyst for the hydrogen evolution reaction (HER), is significantly constrained by its inherent defects, such as poor conductivity and limited active sites. In this work, we report an innovative strategy for fabricating IrO_<i>x</i>-doped Ni(OH)₂ nanosheets (approximately 30 nm in thickness) with multiple vacancies and high surface area induced by Ar plasma. The strong electronic interaction across the heterointerface between the IrO_<i>x</i> and Ni(OH)₂ effectively improves the intrinsic conductivity and reduces the reaction barrier. Meanwhile, the optimal ion density and energy within the plasma create a balanced etching effect, which promotes the dissociation of water molecules and the formation of hydrogen intermediates, thereby accelerating reaction kinetics. With an extremely low Ir loading, the optimized Ar-IrO_<i>x</i>-Ni(OH)₂/Ti electrode exhibits excellent HER performance, demonstrating a small overpotential of 69 mV and a Tafel slope of 38 mV dec^–1 in 1 M KOH solution, while sustaining continuous operation for 100 h.