Enhancement of the TiO2 photoactivity for propene oxidation by carbon incorporation using saccharose in hydrothermal synthesis

Abstract

TiO2-C photocatalysts were prepared by hydrothermal synthesis using titanium tetraisopropoxide, saccharose and HCl of variable concentration. The TiO2-C photocatalysts have textural properties similar to those of analogous bare TiO2 samples, but different crystalline phase composition; they only contain anatase instead of an anatase-brookite-rutile mixture in bare TiO2. This reveals that carbon contributes to the stabilization of anatase. Also, the presence of carbon has shown to favor the spherical morphology. The TiO2-C photocatalysts are more active than analogous bare TiO2 ones and P25. The most efficient TiO2-C photocatalysts are those prepared with lower HCl concentration solutions, 0.5 and 0.8 M, which present higher surface area and lower density of hydroxyl surface groups. Carbon, about 0.3–0.7 wt%, seems to be (partially) incorporated into the TiO2 lattice and it likely leads to low electron-hole recombination rate and to emission processes that could contribute to explain the good activity of the TiO2-C samples.