Investigation of photocatalytic activity of titanium dioxide deposited on metallic substrates by DC magnetron sputtering

The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology of the coating were investigated using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Glow Discharge Optical Emission Spectroscopy (GDOES), and X-Ray Diffraction (XRD). The photocatalytic behaviour was studied using electrochemical methods such as open circuit potential measurements, linear sweep voltammetry, impedance measurements. The microstructure and surface morphology of the coating were similar irrespective of the nature of the substrate, while the photocatalytic behaviour was found to vary depending on the substrate type. In general the TiO2 coating on stainless steel was shown to be more photocatalytically active than TiO2 on aluminium. Impedance measurements show higher capacitance for the coating on stainless steel. Mott–Schottky plots indicate multiple donor states for the coating on the stainless steel substrate. The optical reflection spectrometry measurements showed a lower band gap of 0.2 eV for the coating on the stainless steel substrate.