Preparation and enhanced visible-light photocatalytic H2-production activity of CdS-sensitized Pt/TiO2nanosheets with exposed (001) facets

Abstract

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 H₂ production from lactic acid aqueous solution under UV and visible-light (λ ≥ 420 nm) irradiation. It was shown that no photocatalytic H₂-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 H₂-production rates. The morphology of TiO₂ particles had also significant influence on the visible-light H₂-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.