Fabricating S-scheme Sb2S3@CdSe S1– quasi-one-dimensional heterojunction photoanodes by in-situ growth strategy towards photoelectrochemical water splitting

Nowadays, energy and environmental problems are becoming increasingly prominent in society, the development of clean and environmentally friendly energy is in line with the construction of ecological civilization and energy, which have attracted the attention of many researchers over the past decades. Narrow band gap semiconductor Sb2S3 is widely used in the area of solar cells because of its high light absorption coefficient and suitable bandgap width. However, numerous deep-level defects provide plentiful photogenerated carrier recombination sites, which restricts the improvement of photoelectrochemical properties seriously. In this work, S-scheme Sb2S3@CdSexS1–x core-shell quasi-one-dimensional heterojunction photoanodes were prepared on the FTO substrate by a two-step vapor transport deposition (VTD) method, chemical bath deposition (CBD) and in-situ selenization method. The results showed that CdSexS1–x nanoparticles (NPs) were tightly coated on the Sb2S3 nanorods (NRs). The photocurrent density of the Sb2S3@CdSexS1–x photoanodes was 1.61 mA cm–2 under 1.23 VRHE. Compared with the Sb2S3 photoanodes (0.61 mA cm–2), Sb2S3@CdSexS1–x photoanodes obtained a 2.64-fold improvement, and the dark current was effectively reduced. It showed excellent stability and fast photocurrent response in a 600 s optical stability test. It was concluded that: (1) The charge transfer mechanism of the S-scheme can avoid the problem of high recombination rate of photogenerated charge carriers due to the defects of Sb2S3 effectively, and realized spatial separation of photogenerated carriers. (2) The [hk1] oriented Sb2S3 NRs and the formed quasi-one-dimensional heterostructures promote efficient carrier transport. (3) The introduction of Se effectively regulated the band structure of CdS, slowed down the photocorrosion of S, and improved the stability of the photoelectrodes significantly.