Construction of Sb₂S₃/CdS/CdIn₂S₄ cascaded S-scheme heterojunction for improving photoelectrochemical performance

Antimony sulfide (Sb₂S₃) is a relatively abundant and environmentally friendly emerging photovoltaic material, which has been gradually applied in solar cells and photocatalysis. It has high light absorption capacity, but it suffers many deep-level defects and is prone to recombination of electron-hole pairs within itself. Here, by constructing the Sb₂S₃/CdIn₂S₄ S-scheme heterojunction, we avoided the problem that electrons and holes cannot be separated and transported effectively due to many Sb₂S₃ defects (more recombination centers), and improved its application in the field of photoelectrochemical water splitting. Meanwhile, in order to further improve the performance of Sb₂S₃/CdIn₂S₄ photoelectrode, we introduced CdS energy platform between Sb₂S₃ and CdIn₂S₄ to form a Sb₂S₃/CdS/CdIn₂S₄ cascaded S-scheme heterojunction. Compared with Sb₂S₃ monomer, Sb₂S₃/CdS/CdIn₂S₄ had higher absorbance intensity, IPCE value, ABPE value, and lower charge transfer resistance. In addition, the photocurrent density of the Sb₂S₃/CdS/CdIn₂S₄ photoelectrode was about 4.20 mA/cm² (1.23 V vs. RHE), which was 1.3 times higher than that of the Sb₂S₃/CdIn₂S₄ photoelectrode (3.29 mA/cm²) and 3.2 times higher than that of monomer Sb₂S₃ photoelectrode (1.32 mA/cm²). This method offers new prospects for optimizing the performance of antimony chalcogenides photoelectrodes for photoelectrochemical water splitting.