Efficient improvement of photoelectrochemical activity for multiple semiconductor (CdS/PbS/ZnS) co-sensitized TiO2 photoelectrodes by hydrogen treatment

Abstract

In the present work we report a simple and viable approach to improve the photoelectrochemical activity of TiO₂ photoelectrodes. Firstly, a TiO₂ nanotube array film with nanowires directly formed on top (denoted as TiO₂NTWs) was prepared by a simple electrochemical anodization method on a titanium foil. Then the pristine TiO₂NTWs were annealed in a hydrogen atmosphere (denoted as H*TiO₂NTWs). Subsequently, the formation of a CdS, PbS, and ZnS quantum dot (QD) sensitized H*TiO₂NTW photoelectrode was carried out by successive ionic layer adsorption and reaction (SILAR). The best performance of the photoelectrode was TiO₂ NTWs annealed in hydrogen at 350 °C with 4 cycles of CdS plus 2 cycles of PbS and 3 cycles of ZnS. A maximum short-circuit photocurrent density of 3.62 mA cm⁻² was obtained under an illumination of AM 1.5 G, which can boost the photocurrent density of the pristine TiO₂NTWs by up to 503%. The enhancement was attributed to the extension of the light absorption range by hydrogen treatment and QD sensitization.