Combined heterostructures between Bi2S3 nanosheets and H2-treated TiO2 nanorods for enhanced photoelectrochemical water splitting

Abstract

Constructing heterostructures plays a critical role in promoting separation and transfer of photo-generated carriers, which offers great potential in photoelectrochemical (PEC) water splitting. Herein, on the basis of an interesting structure–property relationship, this work provides an effective strategy to improve the photoelectrochemical performance. A hierarchical heterostructure of intercrossed Bi2S3 nanosheets on hydrogen-treated TiO2 nanorods is fabricated via a facile solvothermal method. By virtue of hydrogen treatment, H2-treated TiO2 nanorods (H-TiO2) exhibit a higher PEC performance than bare TiO2 owing to the better charge separation and narrower band gap. Moreover, boosted by the intercrossed heterostructure, the Bi2S3/H-TiO2 heterostructure achieves an optimal photocurrent density of 2.35 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), which is 16 times that of TiO2 photoanode. PEC studies demonstrate that benefitting from the efficient electron transfer and charge separation within the novel intercrossed heterostructure, it exhibits much better photoactivity than 0D nanoparticle under visible light irradiation. Furthermore, the Z-scheme heterojunction formed between hydrogen-treated TiO2 and Bi2S3 can not only enlarge the photo-response range, but also decrease the recombination loss of photogenerated charge carriers. The synergistic effect of hydrogen treatment, intercrossed heterostructure as well as Z-scheme heterojunction ensures the excellent photoelectrochemical performance of Bi2S3/TiO2 photoanode. Based on the exciting result, this work provides a reliable strategy towards the fabrication and application of low-cost and noble-metal-free nanorod-based hierarchical architecture for solar energy conversion.