rGO spatially confined growth of ultrathin In2S3 nanosheets for construction of efficient quasi-one-dimensional Sb2Se3-based heterojunction photocathodes

Antimony selenide (Sb2Se3) is a narrow-band-gap semiconductor that has been increasingly used as an excellent light-harvesting material in photoelectrocatalysis. The unique connections of the one-dimensional (Sb4Se6)n ribbon structural units determine the high anisotropy of their carrier transport. In this study, a reduced graphene oxide (rGO)-modified quasi-one-dimensional Sb2Se3@In2S3 light-trapping heterostructure was successfully constructed by vapor transport deposition followed by an in situ hydrothermal method. The results showed that the thickness of the in situ grown non-layered In2S3 nanosheets was significantly reduced from 30 to 10 nm under the space-confinement effect of rGO, facilitating the construction of light-trapping nanostructures and increasing the electrochemically active surface area of the photoelectrode. The quasi-one-dimensional Sb2Se3@In2S3-rGO nanorod photoelectrode achieved a higher photocurrent density (1.169 mA cm−2), which was 2 and 16 times higher than that of Sb2Se3@In2S3 and pristine Sb2Se3, respectively. The ultrathin In2S3 nanosheets were co-modified with rGO nanosheets to fabricate a brush-like composite photoelectrode that exhibited favourable stability with an average hydrogen production rate of 16.59 µmol cm−2 h−1 under neutral conditions. The experimental results and theoretical calculations both showed that the significant improvement in photoelectrochemical performance can be perfectly explained by the type-II heterojunction mechanism. This study provides a new exploration to design rGO-modified composite photoelectrodes for photoelectrochemical applications.