Improvement of photocatalytic hydrogen generation from CdSe/CdS/TiO2 nanotube-array coaxial heterogeneous structure

• Highly ordered TiO2 NTs were prepared by two-step anodic oxidation method.
• A coaxial heterogeneous structure emerged after coating CdS and CdSe on TiO2 NTs.
• CdSe/CdS/TiO2 NTs showed superior photocatalytic activity.
• A 7-fold enhancement of H2 production was observed after coating CdS/CdSe on TiO2 NTs.

The fabrication and characterization of CdSe/CdS/TiO2 nanotube-array coaxial heterogeneous structure that has potential applications in photocatalytic water splitting and toxic pollutants degradation are investigated. CdSe(top)/CdS(under) double-layer is conformally deposited onto TiO2 nanotubes by successive ionic layer adsorption and reaction (SILAR) and electrochemical atomic layer deposition (ECALD), respectively, for the CdS under layer and the CdSe top layer. Such double sensitized TiO2 nanotubular photoelectrode exhibits significant enhancements in photoconversion efficiency, visible light response, and efficient hydrogen generation. The detailed synthesis process and the surface morphology, phase structure, elemental analysis, and photoelectrochemical properties of the resulting films with the CdSe/CdS/TiO2 nanotube-array coaxial heterogeneous structure are discussed. The photoconversion efficiency of 9.47% and hydrogen generation rate of 10.24 ml h−1 cm−2 were observed. Both values are a 7-fold enhancement compared with that of the pure TiO2 nanotube. The as-prepared photoelectrode presents potential application for industrialized photocatalytic hydrogen generation in the future.