Roles of the dual-cocatalyst in the Pt-PdS/CdS showing exceptional high quantum efficiency for photocatalytic hydrogen production

Anatase and rutile TiO2 were investigated with photoluminescence (PL) techniques under weak excitation condition. The visible emission band was assigned to the donor-acceptor recombination. Oxygen vacancies and hydroxyl groups mainly serve as the donor and acceptor sites, respectively. The NIR luminescence is originated from the recombination of trapped electrons with free holes. The carrier dynamics in anatase TiO2 are sensitively affected by heat treatment and the presence of oxygen, while the decay processes stay relatively unchanged for rutile TiO2. The trap states in TiO2 may largely influence the photocatalysis process of TiO2 and may determine the photocatalytic activity.