Effect of the anatase-rutile contact in gas phase toluene photodegradation quantum efficiency

A series of TiO2 samples prepared by a microwave assisted method followed by spray drying and calcination were tested in gas-phase photodegradation of toluene under UV and Sunlight-type illumination conditions. Samples were characterized using X-ray diffraction, porosimetry, UV-visible and photoluminescence spectroscopies as well as transmission and scanning microscopies. Their photochemical behavior was analyzed through their reaction rate and efficiency parameters, the later measured as both the apparent and true quantum efficiency. To interpret photocatalytic properties we carried out a study of the main physico-chemical variables affecting photoactivity and particularly its measurement through the efficiency parameter. In particular we focus on quantifying the catalytic effect of the anatase-rutile interface with respect to a parent anatase material prepared at different calcination temperature and in interpreting quantitatively such enhancement using the above mentioned physico-chemical analysis of the efficiency parameter. The study shows that there are some counteracting physical effects in the toluene photodegradation true quantum efficiency presented by anatase-rutile samples with respect to parent anatase counterparts. (C) 2016 Elsevier B.V. All rights reserved.