Thermal stabilization of commercial photocatalyst by Zr(IV) organic salts

The thermally activated anatase to rutile conversion is a critical problem in the production of titania-based photocatalytic materials that must withstand temperatures higher than 450 °C either in production or in service. This work describes the thermal stabilization of already formed, commercially available, nanocrystalline anatase (Degussa P25) by sintering in presence of Zr(IV) organic salts. The production of thermally stable, highly active titania photocatalytic layers was demonstrated by screen-printing using specifically developed inks containing the photocatalyst and Zr(IV) organic salts in 1% and 2% Zr/Ti molar ratio. XRD analyses on powder samples demonstrate that the 2% Zr(IV) doped samples are stable at temperatures 200 °C higher than the pure commercial TiO2 phase (see figure). The samples activity was assessed by measuring the photocatalytic degradation of toluene in air at ambient concentration and low irradiance level. The zirconium doped samples demonstrate high photocatalytic activity even after a thermal treatment at 800 °C. The described method can be potentially applied to every deposition process involving the sintering of already formed nanocrystalline anatase.