Type II Heterojunction/Oxidation Cocatalyst-Induced Multichannels Charge Separation in TiO2-Cu2O-PdS Hybrid Enhances Photocatalytic H2 Evolution

Constructing a hybrid photocatalytic system could effectively address the issues of fast recombination of photogenerated charge carriers, poor catalytic reaction kinetics, and low light energy utilization efficiency. In this work, a ternary TiO₂-Cu₂O-PdS composite was rationally fabricated through a stepwise loading method. Photocatalytic hydrogen production experiments show that the ternary composite material achieves a H₂ generation rate of 2618.6 μmol·g^–1·h^–1, which is 1.5 times that of pristine TiO₂. Considering the band structure of Cu₂O and TiO₂, combining XPS and photo/electrochemical analyses with Mott–Schottky tests, a Type II electron transfer behavior induced by a p–n junction is established at the TiO₂-Cu₂O interface under light irradiation, promoting the separation of photogenerated charge carriers. The delocalized electrons in PdS continuously absorb holes, making the migration of photogenerated charge carriers more efficient. Simultaneously, PdS loaded on Cu₂O absorbs holes, preventing the photo-oxidation of Cu₂O. Accordingly, the Type II heterojunction and oxidation cocatalyst provide multiple pathways for charge transfer in improved photocatalytic hydrogen production.