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

ABSTRACT The integration of gallium phosphide (GaP) with TiO 2 provides a promising approach to enhance the separation of photogenerated electrons and holes, thus improving photocatalytic efficiency. GaP-TiO 2 photocatalysts (0.4-7.6 wt% GaP) were prepared via the wet impregnation of commercial GaP onto TiO 2 synthesized using sol-gel method in a reverse micellar environment. The surface element composition and structural, textural, optical, and electronic properties of the GaP-TiO 2 photocatalysts were investigated. The results confirm the successful formation of an S-scheme heterostructure in the GaP-TiO 2 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 TiO 2 , facilitating separation and reducing recombination, thus boosting overall photocatalytic performance.