Discontinuity‐Enhanced Thin Film Electrocatalytic Oxygen Evolution

Thin film electrocatalysts allow strong binding and intimate electrical contact with electrodes, rapid mass transfer during reaction, and are generally more durable than powder electrocatalysts, which is particularly beneficial for gas evolution reactions. In this work, using cobalt manganese oxyhydroxide, an oxygen evolution reaction (OER) electrocatalyst that can be grown directly on various electrodes as a model system, it is demonstrated that breaking a continuous film into discontinuous patches can significantly enhance the overall OER performance without sacrificing long‐term stability even under elevated electrocatalytic stress. Discontinuous films with higher edge‐to‐area ratios exhibits reduced overpotentials, increased turnover frequency, and more pronounced current increase after electrochemical conditioning. Operando Raman spectroscopy studies during electrocatalysis reveal that the film edges require lower potential barrier for activation. Introducing discontinuity into thin film electrocatalysis can thus lead to the realization of high performance yet highly robust systems for harsh gas evolution reactions. A discontinuous cobalt manganese oxyhydroxide (CMOH) film, which is deposited on gold‐coated pyramidal substrates, shows much higher atom efficiency and performance in the oxygen evolution reaction (OER) than completely continuous ones. The heterojunction edges facilitate charge transport and kinetics. This concept is highly valuable to reduce the quantity of catalysts, while gaining even better, durable OER activity.