Surface Modification of TiO2 by Phosphate: Effect on Photocatalytic Activity and Mechanism Implication

TLDR: In this paper, the photocatalytic activity of as-modified TiO2 under UV irradiation was investigated and it was found that the effect of phosphate modification is attributed to the surface-bound phosphate anion.

Abstract: Phosphate modified TiO2 photocatalysts were prepared by phosphoric acid treatment before or after TiO2 crystallization. Substrates with different structures were chosen to explore the photocatalytic activity of as-modified TiO2 under UV irradiation. It was found that the effect of phosphate modification is definitely attributed to the surface-bound phosphate anion, and the modification by phosphate can affect both the rates and pathways of photocatalytic reactions, which are of great dependence on the structures and properties of substrates. The degradation of substrates (such as 4-chloropehenol, phenol, and rhodamine B) with weak adsorption on the pure TiO2 was markedly accelerated by phosphate modification, while substrates (such as dichloroacetic acid, alizarin red, and catechol) with strong adsorption exhibited a much lower degradation rate in the phosphate modified system. A much higher amount of hydroxyl radical was produced in phosphate modified system. All of the experimental results imply that ph...