Photoelectrochemical water splitting using TiO2 nanorod arrays coated with Zn-doped CdS

Abstract

The rational design of heterojunction structure as photoanode provides an effective route to improve the efficiency of photoelectrochemical (PEC) water splitting. Herein, we design and fabricate CdS nanoparticle/TiO2 nanorod array heterostructures through a facile hydrothermal process. With the assistance of a ZnO interlayer between CdS and TiO2 prepared by atomic layer deposition technique followed by microwave hydrothermal reaction, uniform Zn-doped CdS/TiO2 shell/core arrays are attained. Via tuning the ZnO thickness and CdS deposition time, the optimum Zn-doped CdS/TiO2 sample exhibits a superior PEC performance with a photocurrent of 3.38 mA cm−2 at 1.23 V versus RHE, which is 6.0 and 1.4 times higher than pristine TiO2 and CdS/TiO2, respectively. Moreover, the corresponding onset potential of Zn-doped CdS/TiO2 is obviously shifted toward the negative potential direction by 450 and 130 mV, respectively. The performance enhancement is attributed to the improved electron–hole transport and separation ability, stronger light absorption and higher photoactivity.