Enhanced photocatalytic performance of gully-like AgI/Cu–TiO2 composites with synergistic effects of phase junction and S-scheme heterojunction

Using polystyrene (PS) spheres as templates, Cu–TiO₂(G) photocatalysts with gully structures were prepared by the sol–gel and ion doping method. AgI/Cu–TiO₂(G) composites were then successfully prepared via AgI nanoparticles depositing on Cu–TiO₂(G) composites in situ. The characterization results show that the composite material presents uneven gully morphology, and gully widths is uniform and neatly arranged. Cu doping and AgI loading cooperatively improve the visible light absorption of AgI/Cu–TiO₂(G) composite and reduce the band gap energy of the material. In addition, in AgI/Cu–TiO₂(G) composites, anatase TiO₂ forms phase junctions and heterojunctions with rutile TiO₂ and AgI, respectively, which improve the separation and migration efficiency of photogenerated carriers. AgI/Cu–TiO₂(G) composites exhibit excellent photocatalytic activity in the multi-mode photocatalytic degradation reaction. Meanwhile, this composite material demonstrates a higher catalytic activity in the photocatalytic water decomposition for hydrogen production experiments under simulated sunlight irradiation, and its hydrogen production rate is approximately 10.8 times that of pure TiO₂. The charge separation efficiency is enhanced because the S-scheme heterojunction is constructed between AgI and TiO₂, and the homojunction is formed between the anatase and rutile phases of TiO₂, which further improving the photocatalytic performance.