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

Abstract

Electrolysis of seawater for hydrogen (H 2 ) production to harvest clean energy is an appealing approach. In this context, there is an urgent need for catalysts with high activity and durability. RuO 2 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 RuO 2 (S-RuO 2 ) 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-RuO 2 -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-RuO 2 electrocatalyst is highly protected by the S-doped surface, which repels Cl – in alkaline seawater. This investigation presents a feasible strategy for designing RuO 2 -based seawater splitting catalysts with both high performance and good resistance to anodic corrosion.