A novel photoelectrochemical approach for efficient assessment of TiO2 pigments weatherability

Abstract Weatherability of TiO2 pigments can be improved by suppressing the TiO2 photoactivity with surface coating of insulating oxides. To develop an effective, accurate and high-sensitivity rapid weatherability assessment method is necessary for the product quality control during the pigment production. The present work proposed a novel photoelectrochemical (PEC) approach to assess the weatherability of various commercial TiO2 pigments including the naked, Si-Al and Zr-Al oxide coated TiO2. The photoactivity of those samples was evaluated by monitoring their anodic photocurrents towards water oxidation reaction. Coated TiO2 showed much decreased photocurrents than the naked one due to the inhibited holes interfacial transfer by surface oxides, suggesting their improved weatherability. Compared to the traditional assessment method of dye photodegradation, the PEC approach is advantageous in both fast detection and high sensitivity. Moreover, the PEC approach can perform a deep exploration into the suppression mechanism of the TiO2 photoactivity with different surface oxide layers.