Preparation and enhanced visible-light photocatalytic H-2-production activity of CdS-sensitized Pt/TiO2 nanosheets with exposed (001) facets

CdS-sensitized Pt/TiO2 nanosheets with exposed (001) facets were prepared by hydrothermal treatment of a Ti(OC4H9)(4)-HF-H2O mixed solution followed by photochemical reduction deposition of Pt nanoparticles (NPs) on TiO2 nanosheets (TiO2 NSs) and chemical bath deposition of CdS NPs on Pt/TiO2 NSs, successively. The UV and visible-light driven photocatalytic activity of the as-prepared samples was evaluated by photocatalytic H-2 production from lactic acid aqueous solution under UV and visible-light (lambda >= 420 nm) irradiation. It was shown that no photocatalytic H-2-production activity was observed on the pure TiO2 NSs under UV and/or visible-light irradiation. Deposition of CdS NPs on Pt/TiO2 NSs caused significant enhancement of the UV and visible-light photocatalytic H-2-production rates. The morphology of TiO2 particles had also significant influence on the visible-light H-2-production activity. Among TiO2 NSs, P25 and the NPs studied, the CdS-sensitized Pt/TiO2 NSs show the highest photocatalytic activity (13.9% apparent quantum efficiency obtained at 420 nm), exceeding that of CdS-sensitized Pt/P25 by 10.3% and that of Pt/NPs by 1.21%, which can be attributed to the combined effect of several factors including the presence of exposed (001) facets, surface fluorination and high specific surface area. After many replication experiments of the photocatalytic hydrogen production in the presence of lactic acid, the CdS-sensitized Pt/TiO2 NSs did not show great loss in the photocatalytic activity, confirming that the CdS/Pt/TiO2 NSs system is stable and not photocorroded.