Loading of CdS nanoparticles on the (101) surface of elongated TiO2 nanocrystals for efficient visible-light photocatalytic hydrogen evolution from water splitting

Abstract

Abstract The production of hydrogen gas through photocatalytic water splitting has attracted extensive attention owing to the increasing global energy crisis. In this work, elongated TiO 2 nanocrystals along [0 0 1] orientation with stepped (1 0 1) surface were successfully synthesized via a facile solvothermal method and subsequently sensitized by CdS nanoparticles for efficient visible-light photocatalytic hydrogen evolution from water splitting. The diameter and length of the elongated nanocrystals can be controlled by the Cd(CH 3 COO) 2 ·2H 2 O additive, which serves as not only reactant but also structure directing agent. The morphology, microstructure, crystal phase, chemical composition and photoelectrochemical performance of the as-obtained TiO 2 nanocrystals and CdS nanoparticles sensitized TiO 2 nanocrystals have been carefully investigated via various characterizations. Transmission electron microscopy (TEM) revealed that the CdS nanoparticles were contacted with the (1 0 1) surface of the elongated TiO 2 nanocrystals, which is significant for the accelerated separation of photoinduced charge carriers. The synthesized CdS sensitized TiO 2 nanostructures exhibit strong visible-light absorption capability and enhanced photocatalytic activity for hydrogen generation from water splitting under visible light irradiation ( λ > 400 nm). The hydrogen production rate of CdS sensitized TiO 2 nanocrystals can reach 3.85 mmol h −1 g −1 when the optimal Cd/Ti molar ratio is 0.17. A feasible mechanism is proposed for the photoexcited electrons transfer from CdS nanoparticles to the stepped (1 0 1) surface of anatase TiO 2 nanocrystals. This work offers an efficient way to synthesize composite photocatalysts in nanoscale for improved separation efficiency of photoexcited charge carriers.