Optimization of the facet structure of cobalt oxide catalysts for enhanced hydrogen evolution reaction

Abstract

The structure–property relationship plays a crucial role in further exploring the mechanism of hydrogen production by photocatalytic water splitting. Here, we utilize a simple hydrothermal method to synthesize three Co₃O₄ catalysts with different exposed crystal facets to elucidate their catalytic mechanism at the atomic level. Co₃O₄ microflowers, nanotruncated octahedra and nanorods have mainly exposed {112}, {011} and {001} crystal planes, respectively, and the concentration and distribution of Co²⁺ and Co³⁺ active sites on the surface are different. Further results indicate that the {112} and {011} planes with abundant Co³⁺ sites exhibit catalytic activity superior to that of the {001} plane. Surface atomic configuration and EPR studies manifest that the presence of octahedral coordinated Co³⁺ sites optimizes the photocatalytic hydrogen evolution activity. This work reveals the importance of regulating surface atomic configuration and catalytic active sites, and opens a new avenue for the development of solar-driven water splitting.