Effect of brookite on the photocatalytic properties of mixed-phase TiO2 obtained at a higher temperature

•Nanometric, multi-phase TiO2 powders containing brookite were obtained.•The presence of brookite inhibits the transformation of anatase–rutile up to 700 °C.•Powders containing brookite synthesized at 700 °C have better photocatalytic properties than P25. The paper presents the synthesis and properties of nanometric TiO2 powders obtained by the sol–gel method at elevated temperatures. The presence of brookite inhibits the anatase - rutile transformation at higher temperatures. Even after the treatment of gel at 700 °C, a large amount of anatase in the TiO2 powders was found. Measurements in the UV–vis range were performed to determine the optical band-gap of TiO2. Results of photocatalytic tests for the degradation of RhB and NO under UV are also presented. The decomposition efficiency of the powders was compared with the P25 before and after treatment at 700 °C. The obtained powders despite being prepared at this temperature were more efficient in both RhB and NO decomposition compared to the reference sample. The results indicate the possibility of modifying materials that are produced or work at high temperatures, by adding such TiO2 with high photocatalytic capacity in the UV range.