Controlling degradable activities of water oxidation anode via facile surface reconstruction

Robustness and efficiency are crucial factors for being a highly active electrocatalyst in water electrolysis system (WES). In the case of metal oxide catalysts, the thermodynamic instability under oxygen evolution reaction (OER) condition has been a bottleneck that degrades electrode activity. In this study, we provide a post-treatment that enables further improvement of electrode activity by restructuring metal oxides. The SS-based metal oxide electrode was synthesized through hydrothermal synthesis (HY) and subsequent post-acidic immersion process (HYAi) using earth-abundant stainless steel (SS) 304 plate as a substrate material. The HYAi electrode showed improved electrochemical activities with a lower charge transfer resistance (Rct) and higher surface roughness factor (RF) compared to HY when the prolonged OER potential was applied under alkaline media. Moreover, even after 10,000 cycles of rapid cycling, HYAi showed reduced overpotential of 276.7 mV at 10 mA cm−2, while HY degraded to 304 mV. The enhanced electrochemical activities were confirmed by observing catalytic surface that conversion of oxide to stable (oxy)hydroxide was observed. Our novel approach to rearranging catalytic surface will provide deeper insights for designing improved OER catalyst.