Combinatorial CVD: New Oxynitride Photocatalysts

Combinatorial atmospheric pressure chemical vapour deposition (cAPCVD) was used to synthesise a film with mixed gradating phases from pure orthorhombic pseudo-brookite Ti3-delta O4N (0.06 < delta < 0.25) to interstitial N-doped anatase TiO2 on a single film. The film was characterized via Raman mapping and X-ray photoelectron spectroscopy (XPS). Film thicknesses were determined by Swanepoel method manipulations of UV-visible reflectance spectra and side-on scanning electron microscopy (SEM). Using a novel flat-bed digital scanning technique, the photocatalytic activity of the film to dichloroindophenol (DCIP) degradation under 365 nm light was also mapped. This allowed for the systematic investigation on the effect of pseudo-brookite: interstitial N-doped anatase phase composition, indicating pseudo-brookite to be the more photocatalytically active material. Films synthesized by the cAPCVD route analysed in conjunction with mapping analysis tools is a shortcut to identifying numerous phases and compositions and their functional property relationships on a single film, offering a rapid method for analysis of phase-space.