Enhanced photocatalytic properties of N-P co-doped TiO2 nanosheets with {001} facets

Nitrogen (N) and phosphorus (P) co-doped anatase TiO2 nanosheets were realized by low-temperature self-doping N-TiO2 followed by high-temperature P doping with foreign precursor. It is found that P doping process can maintain good TiO2 nanosheets morphology with exposed {001} facets. Chemical state of dopants indicates that N and P atoms replace O on O sites in TiO2 lattice. Compared with pure TiO2 and N-doped TiO2, N-P co-doped TiO2 nanosheets exhibits stronger optical absorption and higher degradation rate of dye molecules in visible light regime. The enhanced photocatalytic properties are attributed to two factors. On one hand, N-P co-doping can effectively reduce band gap of TiO2 from 3.20 to 2.48 eV, leading to an enhancement of the absorption in visible light regime. On the other hand, the presence of exposed {001} facets of TiO2 nanosheets can induce the effective separation of photogenerated electrons and holes in reaction.