Electrodeposited CZTS loaded titania nanotubes for photocatalytic water splitting

Abstract

Copper Zinc Tin Sulphide (Cu2ZnSnS4 (CZTS)) is a promising semiconductor material with optimum direct band gap of 1.4-1.6 eV, large light absorption coefficient (> 104 cm-1) and p-type electrical conductivity. In addition, its earth abundant and non-toxic elemental constituents make it a good candidate to replace the CdTe and CIGS absorber layers used in thin film solar cells. Also, it has properties that make it useful as a buffer layer that helps to reduce the effective band gap of TiO2 when used as an anode for photocatalytic splitting of water. We prepared titania nano tube (TNT) arrays by anodization of titanium foil. Raman spectrum of TNT confirmed the presence of pure anatase phase of TiO2. Field emission scanning electron microscopy images were obtained to analyse the surface morphology of TNT. CZTS sensitized titania nano tube arrays were then prepared by the electrodeposition of CZTS thin films over TNT arrays. FESEM images of the CZTS sensitized titania nano tube arrays showed that the electrodeposited CZTS layer had a fibrous structure. A photo electro chemical (PEC) cell was set up with CZTS sensitized titania nanotubes as anode. An anodic current density of 0.19 mA/cm2 was shown by the PEC cell when the anode was irradiated with blue light of wavelength 430 nm at power 50 mW/cm2. The incident photon to current conversion efficiency was 1.1 %.