The photocatalytic degradation of the synthetic red mordant dye alizarin on TiO2-In2O3 semiconductors as a function of the In2O3 content (1-12 wt%) was studied. High specific surface areas varying from 122 to 178 m2 g−1, depending on the In2O3 content, were obtained. A modification of the Eg band gap from 3.12 to 3.50 eV was obtained for low and high In2O3 contents. The XRD spectral patterns of the solids showed that anatase is the main crystalline titania phase. STEM-EDX chemical maps show that the In2O3 was found highly dispersed on the surface of the TiO2-In2O3 mixed oxide. By means of TEM images, nanostructured materials with crystallite sizes between 8 and 12 nm were identified. The photocatalytic activity for the alizarin degradation showed a maximum with the catalyst with 3.0 wt% of In2O3. The role of the In2O3 developing an optimal alizarin adsorption on the TiO2-In2O3 semiconductors is discussed
Keywords: Alizarin photodegradation, TiO2-In2O3 nanosized semiconductors, Titania-indium STEM-EDX chemical map, Titaniaindium sol-gel doping.