Construction of a Rh-doped SrTiO3/g-C3N4 p-n heterojunction for enhanced photoelectrochemical performance

Semiconductor photoelectrochemical (PEC) technology, capable of generating hydrogen energy from water and solar energy, has emerged as a promising solution to address environmental and energy challenges. Rhodium-doped strontium titanate (Rh doped SrTiO3, RST) is regarded as a highly promising photocathode material for PEC systems. Nevertheless, the PEC performance of RST is hindered by inefficient carrier separation and poor charge transfer properties. In this paper, a hybrid RST/g-C3N4 heterojunction sample was prepared by a simple method. The pure RST sample possesses the ability to absorb visible light and exhibit p-type semiconductor characteristics with a negative photocurrent value of -6.2 mu A cm-2, and can be used as a photocathode material in PEC systems. The enhanced PEC performance with larger photocurrent values can be observed in the heterojunction samples. A photocurrent value of -26.5 mu A cm-2 was achieved in the optimized heterojunction, which is 4.3 times higher than the RST sample. This enhanced PEC performance can be attributed to the formation of a p-n junction between RST and g-C3N4 in composite samples. The p-n junction with built-in electric field and good band alignment will facilitate the more efficient separation and transfer of carriers, leading to enhanced PEC performance.