Charged matrix stabilized cobalt oxide electrocatalyst with extraordinary oxygen evolution performance at pH 7

Cheap, durable, and efficient oxygen evolution reaction (OER) catalysts applicable in near-neutral electrolytes are highly desired in various energy conversion applications for establishing carbon neutrality . However, it is very challenging for noble metal-free materials to be efficiently operated in such conditions, and the screening of new compounds has reached a bottleneck for this purpose. Herein, we show that significant stability enhancement can be achieved via novel interfacial interactions through rational integration of components, which opens up a new opportunity to meet this challenge. We realized a mixed oxides film of Co 3 O 4 and CoNb 2 O 6 with a unique heterogeneous architecture, where the Co 3 O 4 active site receives strong protection against dissolution from niobate phases via Coulombic interaction. Moreover, the cobalt niobate phase also promotes the overall charge transport, as suggested by the impedance study. As a result, the heterogeneous catalyst exhibits attractive stability and activities in neutral and even weak acidic electrolytes. This work indicates that the screening criteria of novel ternary oxides OER catalysts should not be limited to the intrinsic property of new phases, and that controlled phase separation can be a convenient tool and a new paradigm for future works.