Type II/Schottky heterojunctions-triggered multi-channels charge transfer in Pd-TiO2-Cu2O hybrid promotes photocatalytic hydrogen production

Rapid charge recombination, limited light response, and slow surface reactions were observed in the photocatalysts, thereby limiting their future-oriented applications in photocatalytic hydrogen production through water splitting. Constructing a multi-channel charge separation photocatalysis system could solve those questions. In this study, Pd-TiO 2 -Cu 2 O composites were successfully accomplished via a facile chemical reduction method. The Pd-TiO 2 -Cu 2 O composite exhibited improved photocatalytic hydrogen production (13069.7 μmol g −1 h −1 ), which was over 6 times as much as that of pure TiO 2 . Based on the photo/electrochemical measurements, it was proposed that a Type II heterojunction was formed at the TiO 2 -Cu 2 O interface under light irradiation, and concurrently, a Schottky barrier was established between Pd and TiO 2 . Accordingly, the Type II heterojunction-created built-in electric field would facilitate the separation of photogenerated charges. Simultaneously, the introduction of Pd accelerates the accumulation of electrons and further enhances the charge transfer rate. The combination of such a Type II heterojunction and Schottky junction synergistically created a multi-channel charge separation system, optimizing surface reactions and thus improving photocatalytic efficiency. This work provided a rational approach for building efficient multi-component photocatalysis systems featuring Type II heterojunction/Schottky junction for photocatalytic hydrogen evolution.