Electron migration pathways in S-scheme GaP-TiO2 photocatalysts and their implications for photocatalytic hydrogen production

Abstract

The integration of gallium phosphide (GaP) with TiO₂ provides a promising approach to enhance the separation of photogenerated electrons and holes, thus improving photocatalytic efficiency. GaP-TiO₂ photocatalysts (0.4-7.6 wt% GaP) were prepared via the wet impregnation of commercial GaP onto TiO₂ synthesized using sol-gel method in a reverse micellar environment. The surface element composition and structural, textural, optical, and electronic properties of the GaP-TiO₂ photocatalysts were investigated. The results confirm the successful formation of an S-scheme heterostructure in the GaP-TiO₂ composite and reveal the charge carrier migration pathway. This heterostructure, combined with a photocurrent doubling effect induced by methanol in the reaction, significantly enhances hydrogen production during the photocatalytic decomposition of aqueous methanol solutions. The improved performance of these photocatalysts is attributable to the synergistic interaction of GaP and TiO₂, facilitating separation and reducing recombination, thus boosting overall photocatalytic performance.