Super-Exchange Interaction Induced Overall Optimization in Ferromagnetic Perovskite Oxides Enables Ultrafast Water Oxidation

Abstract

Oxygen evolution reaction (OER) is crucial in many renewable electrochemical technologies including regenerative fuel cells, rechargeable metal–air batteries, and water splitting. It is found that abundant active sites with favorable electronic structure and high electrical conductivity play a dominant role in achieving high electrocatalytic efficiency of perovskites, thus efficient strategies need to be designed to generate multiple beneficial factors for OER. Here, highlighted is an unusual super-exchange effect in ferromagnetic perovskite oxide to optimize active sites and enhance electrical conductivity. A systematic exploration about the composition-dependent OER activity in SrCo1−xRuxO3−δ (denoted as SCRx) (x = 0.0–1.0) perovskite is displayed with special attention on the role of super-exchange interaction between high spin (HS) Co3+ and Ru5+ ions. Induced by the unique Co3+–O–Ru5+ superexchange interactions, the SCR0.1 is endowed with abundant OER active species including Co3+/Co4+, Ru5+, and O2 2−/O−, high electrical conductivity, and metal–oxygen covalency. Benefiting from these advantageous factors for OER electrocatalysis, the optimized SCR0.1 catalyst exhibits a remarkable activity with a low overpotential of 360 mV at 10 mA cm−2 , which exceeds the benchmark RuO2 and most well-known perovskite oxides reported so far, while maintaining excellent durability. This work provides a new pathway in developing perovskite catalysts for efficient catalysis.