Rational construction of high-active Co3O4 electrocatalysts for oxygen evolution reaction

Rational construction of high-efficiency electrocatalysts for oxygen evolution reaction (OER) is critical for renewable-energy technologies, but it is highly challenging to rationally regulate their surface structures to improve the OER performance. Herein, we proposed a "model-etching" strategy to investigate chemical etching of Co3O4. The cubic Co3O4 nanocrystals enclosed by well-defined facets are synthesized as model crystals, whose uniform surface structures allow us to study the etching mechanism at atomic level. Etching kinetics study together with DFT calculations discloses that {111} facets, the highly active facets for OER, serve as etch-stop facets in the etching reaction and H2SO4 molecules play a special role in creating surface Co2+, the active center of OER. These results direct us to rationally optimize the surface structures of Co3O4 to develop highly active OER electrocatalysts. The favorable performance of overpotential (η) and the Tafel slope decrease even to 268 mV@10 mA·cm−2 and 74 mV·dec−1, respectively. In general, our study shows that chemical etching of model crystals could help us rationally construct high-efficiency electrocatalysts.