Effect of phase composition, morphology, and specific surface area on the photocatalytic activity of TiO2 nanomaterials

The synergistic effect between anatase and rutile TiO2 particles for photocatalysis has been widely reported. Besides the phase composition, both morphology and specific surface area play important roles in affecting the photocatalytic activity of TiO2-based materials. However, comprehensive study of the effects of these properties is missing so far. Using a facile soft-chemical strategy, we synthesize a series of TiO2 samples with desired phase composition, morphology, and specific surface area, but otherwise identical properties. The correlation of these properties to the photoreactivity is investigated by degrading three typical dye molecules. The composite with anatase-to-rutile ratio as 7 : 3 displays optimal results. Meanwhile, we find an interlaced influence of morphology and specific surface area. The superior activity is achieved in a 0D/1D TiO2 heterogenous composite even though it possesses much lower surface area than pure 0D particles. We proposed that the improvement is due to the combined effect of higher surface-to-volume ratio of 0D particles and lower carrier recombination rate of 1D nanorods. In this way, TiO2-based materials could reach the maximal photocatalytic performance if designing a 0D/1D heterogenous structure with appropriate phase composition and high specific surface area.