Photoelectrochemical Performance of CdS/ZnSe Core/Shell Nanorods Grown on FTO Substrates for Hydrogen Generation

Abstract

One-dimensional nanostructured CdS/ZnSe core/shell photoelectrodes were prepared to show improved photocatalytic properties compared to CdS thin film photoelectrodes. The enhanced surface area and the type-II energy band structure originating from the nanorod growth and ZnSe nanoparticle decoration, respectively, are attributed to the improved photoelectrochemical performance. A mild solution based approach enabled the formation of uniform and high-density CdS nanorods having a diameter and a length of ∼15–20 nm and < 1 μm, respectively. As-synthesized CdS nanorods were uniformly coated with ZnSe nanoparticles to form ZnSe shell with ∼3 nm thickness using a spin coating method. According to the energy bandgaps of CdS nanorods and ZnSe nanoparticles estimated by UV-Visible spectrum analyses, their energy band alignment was expected to be the type-II band structure. This type-II band structure could induce the charge separation of carriers in the semiconductor electrodes and in turn could accelerate the photocatalytic reactions for efficient water splitting not only at lower but also at higher bias voltages compared to CdS thin film electrodes and bare CdS nanorod electrodes.