Correlation between Titanium foil substrate purity and TiO2 NTs; physical and electrochemical properties for enhanced photoelectrochemical applications

Abstract

Titanium oxide (TiO2) nanotubes were grown with two different purity of Titanium foil using anodization method. A new contribution to the knowledge of purity substrate dependence of structural, morphological, optical properties is reported. We have discovered that the purity of titanium has an important effect on the photoelectrochemical performance and photoconversion efficiency of TiO2. Scanning electron microscopy (SEM) images has shown that the thickness of TiO2 nanotube increases with the increase of the purity percentage. X-ray diffraction has revealed that the crystalline nature of TiO2 NTs anatase phase is improved when increasing the purity of the titanium foil. Through photoluminescence measurement, only the intensity was decreased with the increasing of percentage purity of substrate. Using electrochemical impedance spectroscopy data, the interface was modeled by an equivalent circuit approach, which demonstrate that the double layer capacitance (Cdl) increased with the Ti purity. The photocurrent density produced by TiO2/Ti (99.9%) NTs electrode reached 1,5 mAcm−2 about two times higher than that measured on TiO2/Ti (99.7%) NTs and provided the highest value of solar-to-hydrogen energy efficiency η(%). These results indicate that the purity of the substrate have great potential in photoelectrochemical devices.