Visible-light activated titania perovskite photocatalysts: Characterisation and initial activity studies

The effect of partial substitution of the titanium cation on the optophysical properties and photocatalytic oxidation activity of sol-gel synthesised CeCoxTi1 − xO3 + δ perovskite system has been examined. BET surface areas of the perovskite specimens were generally higher (80-130 m2 g−1) than standard Degussa P25 (50 m2 g−1) titania. Although the presence of Ce improved BET area, increased Co content and high calcination temperature was detrimental to nanocrystallinity. Based on UV-Vis diffuse reflectance measurements, perovskite catalysts have significantly lower band-gap energy (1.45-2.15 eV) than P25 (3.2 eV), however, the drop in band-gap energy levelled off at x > 0.1. Using oxidative photodegradation of aqueous Nile Blue solution for activity evaluation, the CeCo0.05Ti0.95O3.97 perovskite sample was the best in the series with a conversion of 91% in the 3-h run and also most suitable for solar photocatalysis since it can be activated by visible light (λ < 785 nm).