Visible-light photocatalytic regeneration of NADH using P-doped TiO2 nanoparticles

P-doped TiO2 nanoparticles were prepared by the sol–gel method and characterized by XRD, BET, SEM, XPS and UV–vis spectrum. The results indicated that the doping of phosphorus could efficiently inhibit the grain growth and enhance the surface area of TiO2 nanoparticles. The doped phosphorus was present as the pentavalent-oxidation state, which can replace a part of Ti4+ in the crystal lattice of anatase. Because P5+ can accept photoelectron as the electron trap center, its doping reduces the recombination rate of photogenerated charge carriers. In addition, P-doped TiO2 nanoparticles also show stronger absorption in the visible light range than the pure sample, because of the formation of an impurity energy level within the band gap of TiO2. Correspondingly, P-doped TiO2 nanomaterials show higher ability of NADH photogenenration under visible-light irradiation than pure TiO2.