High-density accessible Ru-O-Co moieties with accelerated formation of activated oxygen species for freshwater and seawater electrolysis

Promoting the activated oxygen formation and the accessible site density is crucial for boosting the mass and price activity of Ru in water/seawater electrolysis. However, a rational catalyst architecture is lacking to satisfy the above requirements. Herein, Ru was intentionally embedded into few-layer Co3O4 (Ru-Co3O4) to construct high-density accessible Ru-O-Co moieties for water/seawater splitting. The moiety structure accelerates the generation and dissociation of activated H2O during hydrogen evolution reaction (HER), and ensures the rapid evolution of key "activated oxygen" species in oxygen evolution reaction (OER), thus improving HER/OER intrinsic kinetics. Besides, these moieties embedded within few-layer structure effectively promote site formation and utilization. Consequently, compared with Ru/C and Pt/C, an order of magnitude increase in mass and price activity was achieved for bifunctional HER/OER. When applied in an anion-exchange-membrane (AEM) elec-trolyzer, this catalyst realizes industrial-level current densities for freshwater and seawater electrolysis, more than twice than Ru/C(+)||Pt/C(-), and robust durability.