Covalent SO Bonding Enables Enhanced Photoelectrochemical Performance of Cu2S/Fe2O3 Heterojunction for Water Splitting

Abstract The severe charge recombination and the sluggish kinetic for oxygen evolution reaction have largely limited the application of hematite (α‐Fe 2 O 3 ) for water splitting. Herein, the construction of Cu 2 S/Fe 2 O 3 heterojunction and discover that the formation of covalent SO bonds between Cu 2 S and Fe 2 O 3 can significantly improve the photoelectrochemical performance and stability for water splitting is reported. Compared with bare Fe 2 O 3 , the heterostructure of Cu 2 S/Fe 2 O 3 endows the resulting electrode with enhanced charge separation and transfer, extended range for light absorption, and reduced charge recombination rate. Additionally, due to the photothermal properties of Cu 2 S, the heterostructure exhibits locally a higher temperature under illumination, profitable for increasing the rate of oxygen evolution reaction. Consequently, the photocurrent density of the heterostructure is enhanced by 177% to be 1.19 mA cm −2 at 1.23 V versus reversible hydrogen electrode. This work may provide guideline for future in the design and fabrication of highly efficient photoelectrodes for various reactions.