Activating Metal Oxides Nanocatalysts for Electrocatalytic Water Oxidation by Quenching-Induced Near-Surface Metal Atom Functionality

Developing a reliable strategy for the modulation of the texture, composition, and electronic structure of electrocatalyst surfaces is crucial for electrocatalytic performance, yet still challenging. Herein, we develop a facile and universal strategy, quenching, to precisely tailor the surface chemistry of metal oxide nanocatalysts by rapidly cooling them in a salt solution. Taking NiMoO4 nanocatalysts an example, we successfully produce the quenched nanocatalysts offering a greatly reduced oxygen evolution reaction (OER) overpotential by 85 mV and 135 mV at 10 mA cm–2 and 100 mA cm–2 respectively. Through detailed characterization studies, we establish that quenching induces the formation of numerous disordered stepped surfaces and the near-surface metal ions doping, thus regulating the local electronic structures and coordination environments of Ni, Mo, which promotes the formation of the dual-site active and thereby affords a low energy pathway for OER. This quenching strategy is also successfully applied to a number of other metal oxides, such as spinel-type Co3O4, Fe2O3, LaMnO3, and CoSnO3, with similar surface modifications and gains in OER activity. Our finding provides a new inspiration to activate metal oxide catalysts and extends the use of quenching chemistry in catalysis.