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. (C) 2009 Elsevier B.V. All rights reserved.