Hierarchical mesoporous phosphorus and nitrogen doped titania materials: Synthesis, characterization and visible-light photocatalytic activity

Hierarchical mesoporous P- and N-doped titanias were synthesized by the direct phosphation from phosphoric acid and the following nitridation with urea solution. The resulting materials were characterized by XRD, nitrogen adsorption, SEM, TEM, UV–vis, FT-IR and XPS analysis, and their photocatalytic activities were tested by the visible-light photodegradation of Rhodamine B solution. A bimodal mesopore size distribution with a macroporous structure was observed, rendering high surface area with thermal stability. N-doping of the hierarchical mesoporous titania resulted in the band-gap narrowing with improved photocatalytic activity. However, the phosphated titania exhibited higher photocatalytic activity than the N-doped one, but with larger band-gap energy. Further nitridation of phosphated titania resulted in narrower band-gap of the N,P-codoped titania than either N- or P-doped one, exhibiting the further enhanced photocatalytic activity.