LAUSR

Ceria-based OER catalysts have received keen interest in recent years owing to their potential high cost performance. However, despite a flurry of research activities, the mechanism on how ceria activates those hybrid catalysts is still puzzling. Herein, by controllably modifying the oxidation state of Ce in ceria, we elaborately revealed that creating Ce3+ species, which are redox-coupled to Ce4+ under OER condition, could enhance the conductivity and optimize the OH* binding, leading to greatly improved OER activity of the catalysts. More importantly, the ceria-based hybrid catalysts also exhibit excellent long-term stability even when operating at a high current density of 50 mA/cm2 in the strong alkaline electrolyte of 6 M KOH for more than 50 h. This work unveils the underlying role of ceria on improving the activity/stability of ceria-based catalysts and opens the way to design and fabricate commercializable electrocatalysts for water splitting.