Covalent SO Bonding Enables Enhanced Photoelectrochemical Performance of Cu2 S/Fe2 O3 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-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 1.19mA cm-2 at 1.23V versus reversible hydrogen electrode. This work may provide guideline for future in the design and fabrication of highly efficient photoelectrodes for various reactions.