CdS/TiO2 nanotubes hybrid as visible light driven photocatalyst for water splitting

Abstract

Pt-CdS-TiO2 nanotubes (NTs) hybrids were synthesized with various combinations of CdS, TiO2NTs, and Pt by a platinizing, facile ion change and sulfurization process at a moderate temperature. The samples were characterized by XRD and TEM. The photocatalytic activity of the platinized CdS/TiO2 nanotubes hybrid for hydrogen production was evaluated in the aqueous solution containing sodium sulfide and sodium sulfite as hole scavengers under visible light irradiation (λ > 420 nm). The sample prepared by loading CdS on 0.1 wt.% Pt-TiO2NTs (0.1 wt.% Pt-TiO2NTs/CdS) could split water to generate more hydrogen than others. 0.4 wt.% Pt-(CdS/TiO2NTs) was far more efficient than other hybrids. It was known that efficient charge transfer was one of the key factors of high-efficiency hybrid photocatalysts for hydrogen production. The results indicate that the charge transfer is sensitively and greatly affected by how the hybrids are organized. Direct particle-to-particle contact of CdS and TiO2 is basically required to achieve a potential gradient and the Pt particle loaded on the TiO2 particle surface to have the vectorial electron transfer from CdS to TiO2 and last reach the surface of Pt, which benefits the evolution of hydrogen by photocatalytic water splitting.