Modulated Electronic Structure of Co3O4 by Single Atoms for Efficient Anodic Oxygen Evolution in Acid.

ABSTRACT

The challenge of the practical application of a water electrolyzer system lies in the development of low-manufacturing cost, highly active, and stable electrocatalysts to replace the noble metal ones, in order to enable environmentally friendly hydrogen production on a large scale. Herein, a facile method is proposed for boosting the performance of Co3O4 through the incorporation of large-sized single atoms. Due to the larger ionic radius of rare earth metals than that of Co, the incorporation elongates the bond length of Co─O, resulting in the narrowed d-p band centers and the high spin configuration, which is favorable for the interaction and charge transfer with absorbent (*OH). As a result, the Ce-incorporated Co3O4 with the longest Co─O bond length exhibits the best oxygen evolution reaction (OER) performance, specifically, the turnover frequency is over 17 times higher than that of pristine Co3O4 nanosheet under an overpotential of 400 mV. Powered by a commercial Si solar cell, a two-electrode solar water-splitting device combining Ce-incorporated Co3O4 and Pt delivers a solar-to-hydrogen conversion efficiency of 13.53%. The strategy could provide a new insight for improving the performance of OER electrocatalysts in acid toward practical applications.