Surface S-Doped Nanostructured RuO2 and Its Anion Passivating Effect for Efficient Overall Seawater Splitting

Electrolysis of seawater for hydrogen (H2) production to harvest clean energy is an appealing approach. In this context, there is an urgent need for catalysts with high activity and durability. RuO2 electrocatalysts have shown efficient activity in the hydrogen and oxygen evolution reactions (HER and OER), but they still suffer from poor stability. Herein, surface S-doped nanostructured RuO2 (S-RuO2) is rationally fabricated for efficient overall seawater splitting. Doping with S enhances the activity (overpotentials of 25 mV for the HER and 243 mV for the OER), long-term durability (1000 h at 100 mA cm–2), and achieves nearly 100% Faraday efficiency (FE). Moreover, the S-RuO2-based anion exchange membrane seawater electrolyzer requires 2.01 V to reach 1.0 A cm–2 under demanding industrial conditions. Experimental analysis and theoretical calculations indicate that surface S introduction could lower the valence state of Ru, thereby conferring enhanced activity and stability. Furthermore, the nanostructured S-RuO2 electrocatalyst is highly protected by the S-doped surface, which repels Cl– in alkaline seawater. This investigation presents a feasible strategy for designing RuO2-based seawater splitting catalysts with both high performance and good resistance to anodic corrosion.