Efficiency enhancement in a stoichiometrically stable CdS/TiO2 nanotube heterostructure electrode for sunlight-driven hydrogen generation

Abstract

A stoichiometrically stable CdS/TiO₂ heterostructured electrode was developed via electrodeposition for efficient photoelectrochemical conversion. The stoichiometry of CdS and its homogeneous distribution over TiO₂ nanotubes (TNTs) is paramount to achieve excellent current conversion efficiency and photo-stability. Herein, we report a stable photocurrent density of 3.5 mA cm⁻² for an input power density of 50 mW cm⁻² for CdS/TiO₂ nanotubes (CdS/TNTs), which is 17 times higher than that of bare TNTs. Further, the photo-stability of the photoanode was studied under the sequence of light ON/OFF conditions to verify their durability. Our results show that the photoelectrochemical activity of the CdS/TiO₂ heterostructure achieved the highest H₂ production rate of 1.1 ± 0.03 mmol h⁻¹ g⁻¹ for the stoichiometry ratio of 1 : 1 without any co-catalysts. The significance of CdS/TiO₂ stoichiometry towards efficient hydrogen production is presented and discussed in detail.