Effect of calcined atmosphere on the photocatalytic activity of P-doped TiO2

•Phosphorus-doped TiO2 calcined under different atmosphere were as catalysts for methyl orange photodegradation.•P-doped TiO2 calcined under carbothermic atmosphere (R-TiO2) can decrease the concentration of surface O and improve the effect of P species in TiO2 to some extent.•The outstanding photocatalytic activity of P-doped TiO2 is ascribed to the generation of Ti3+ defect sites at the surface or interface of TiO2 caused by P doping.•The activity of recycled P-doped TiO2 was found to retain even after third photodegradation experiment. Titanium dioxide doped with phosphorus was synthesized by the sol–gel method with H3PO4 addition. The samples were calcined at different temperatures under different atmospheres, in order to affect the TiO combination behavior in P-doped TiO2. The physicochemical properties of the prepared samples were investigated using TG-DTA, XRD, FTIR, XPS, TEM and UV–vis. The photocatalytic activity was evaluated by degradation of methyl orange (MO) dye under UV and visible-light irradiation. The results show that P-doped TiO2 calcined in different thermal atmosphere reveals entirely different performances. The XRD and UV–vis analysis reveal that the effect of P species in TiO2 is increased by calcining in reducing atmosphere. Further photocatalytic experiments also display that P-doped TiO2 calcined under carbothermal reduction atmosphere (R-PT) exhibits higher photocatalytic activity than that calcined in air (A-PT). The XPS results confirms that the calcining atmosphere changes the distribution concentration of surface and interface species in P-doped TiO2, such as surface oxygen and Ti3+ sites, resulting in the improved photocatalytic activity and enhanced reutilization performance of R-PT. Further mechanism study illustrates that the promoting photocatalytic activity of P-doped TiO2 are ascribed to the formation of Ti3+ sites rather than exceeding oxygen on the surface. And the carbothermal process helps to reserve these Ti3+ sites during high temperature calcination, resulting in the increased photocatalytic activity of P-doped TiO2, especially when the doping level of P species is relative low.