Epitaxial grown [hk1] oriented 2D/1D BiOS/SbS heterostructure with significantly enhanced photoelectrochemical performance.

Bismuth oxysulfide (BiOS) is a layered material with high carrier mobility, excellent light absorption characteristic and good stability. However, there are few reports about the use of BiOS in photoelectrochemical (PEC) water splitting. In this paper, BiOS nanosheets (NSs) films were prepared on FTO substrates by one-step hydrothermal method, which broke the traditional powder state of BiOS prepared. Based on the high lattice matching between antimony sulfide (SbS) and bismuth sulfide (BiS) obtained from the topological transformation of partial BiOS, SbS nanorods (NRs) with [hk1] predominant orientation were epitaxially grown on the surface of BiOS to establish a transport channel for rapid carrier migration. Titanium dioxide (TiO) electron transport layer with oxygen vacancies was introduced into the back to capture and release electrons, further reducing the recombination rate. The photocurrent density of TiO/BiOS/SbS-annealed photoelectrode at 1.23 V vs. RHE was 4.37 mA/cm, which was 13.7 times that of monomer BiOS. In addition, the TiO/BiOS/SbS-annealed photoelectrode had lower charge transfer resistance and the IPCE value up to 48.22%. This study is of great significance for the application of BiOS based photoelectrodes in the field of PEC water splitting.