Mesoporous-assembled In2O3–TiO2 mixed oxide photocatalysts for efficient degradation of azo dye contaminant in aqueous solution

This work focuses on the improvement of the photocatalytic activity of mesoporous-assembled In2O3–TiO2 mixed oxide photocatalysts for Congo Red (CR) azo dye degradation by varying the In2O3-to-TiO2 molar ratio and calcination temperature. All of photocatalysts are synthesized by a sol–gel process with the aid of a structure-directing surfactant. The results show that the incorporation of In2O3 to the mesoporous-assembled TiO2 can increase the specific surface area and total pore volume, inhibit the anatase-to-rutile phase transformation, and decrease the crystallite size of the resulting In2O3–TiO2 mixed oxide photocatalysts. The mesoporous-assembled 0.05In2O3–0.95TiO2 mixed oxide photocatalyst with an In2O3-to-TiO2 molar ratio of 0.05:0.95 (5 mol% In2O3 incorporation) and calcined at 500 °C exhibits the highest CR dye degradation activity (with reaction rate constant of 0.86 h−1), being considerably higher than that of the commercial P-25 TiO2 powder.