Covalent SO Bonding Enables Enhanced Photoelectrochemical Performance of Cu2S/Fe2O3 Heterojunction for Water Splitting

The severe charge recombination and the sluggish kinetic for oxygen evolution reaction have largely limited the application of hematite (α-Fe₂ O₃ ) for water splitting. Herein, the construction of Cu₂ S/Fe₂ O₃ heterojunction and discover that the formation of covalent SO bonds between Cu₂ S and Fe₂ O₃ can significantly improve the photoelectrochemical performance and stability for water splitting is reported. Compared with bare Fe₂ O₃ , the heterostructure of Cu₂ S/Fe₂ O₃ 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 Cu₂ 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.