Preparation and surface characterization of Ti/SnO2-RuO2-IrO2 thin films as electrode material for the oxidation of phenol

Titanium substrate was coated with mixed metal oxides of SnO2, RuO2 and IrO2. These coatings were prepared by thermal decomposition of the metal chlorides and alkoxides and dip-coated on titanium substrates at 400 °C. The surfaces of the thin films were characterized with various surface analytical techniques. The properties of these electrode materials were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), particle induced X-ray emission (PIXE) and cyclic voltammetry (CV). The surface morphology of the thin films has both compact and porous regions. The average area roughness of the surfaces, as determined by AFM, was found to be ∼150 nm. Distinct oxides of Sn, Ru, Ir and Ti were identified by XRD. RBS confirmed the depth profile of the elements in the thin film and PIXE was used to resolve the Sn and Ru overlapped peaks on RBS spectra. This film acts as an electrocatalyst for the electro-oxidation of model organic compounds, such as phenol in aqueous media. The electro catalytic behaviour is linked to the solid-state properties of the films. The film composed of 40% Ru gave the optimum catalytic response for the oxidation of phenol. CV measurements indicated a decomposition potential of 200 mV (versus the Ag/AgCl reference electrode) for phenol on the Ti/SnO2-RuO2-IrO2 electrode.