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

Premature charge recombination and slow kinetic for oxygen evolution reaction have widely limited the application of hematite (α-Fe2O3) for water splitting. We designed [1] a Cu2S/Fe2O3 heterojunction and discovered that the formation of covalent S-O bonds between Cu2S and Fe2O3 can improve the photoelectrochemical performance and stability for water splitting. Compared with bare Fe2O3, the heterostructure of Cu2S/Fe2O3 permits the photoelectrode enhanced charge separation and charge transfer,and an extended range for light absorption, and decreased charge recombination rate. Additionally, due to the thermal properties of Cu2S, the heterostructure exhibits locally a higher temperature under illumination, profitable for increasing the rate of oxygen evolution reaction. Following this slight improvement, the photocurrent density of the heterostructure is enhanced by a factor of almost 2 to around 1.2 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.<br/><br/>[1] Yan Zhang, Yuan Huang, Shi-Shi Zhu, Yuan-Yuan Liu, Xing Zhang, Jian-Jun Wang, Artur Braun, Covalent S-O Bonding Enables Enhanced Photoelectrochemical Performance of Cu₂S/Fe₂O₃ Heterojunction for Water Splitting, Small Vol. 17, Issue 30, (2021), 2170154, https://doi.org/10.1002/smll.202170154