Semi-metallic hydroxide supported single-atom catalysts for sustainable water oxidation

Developing efficient electrocatalysts towards water oxidation is of critical importance for numerous environmental and energy technologies. Single-atom catalysts have been widely recognized as a promising route, they are however often anchored on semiconducting substrates such as hydroxides, which inherently limits the electrical conductivity and overall catalytic efficiency. In this work, single-atom Ru catalysts are immobilized on a semi-metallic layered double hydroxide substrate (Ru-SM LDH) to achieve highly efficient water oxidation. The as-designed Ru-SM LDH catalyst displayed an overpotential of 270 mV to deliver an oxygen evolution reaction (OER) current density of 100 mA cm⁻², which was 60 mV lower than that of commercial RuO₂. <i>In-situ</i> electrochemical impedance spectroscopy revealed that Ru-SM LDH exhibited a reduced solution resistance and diminished charge transfer resistance during catalysis, leading to the enhanced OER performance. An electrolyzer assembled with Ru-SM LDH anode and commercial Ni mesh cathode achieved a water electrolysis current density of 400 mA cm⁻² at 1.65 V and demonstrated exceptional stability for 1000 h, surpassing that of Ni||Ni electrolyzer (1.92 V, 350 h). These findings established the design of single-atom catalysts supported on semi-metallic hydroxide substrates as a robust pathway toward efficient water electrolysis catalysts.