Solid-state synthesis and photodegradation property of anatase TiO2 micro-nanopowder by sodium replacement

Abstract

To investigate the effect of the doping of alkali metal on the band structure and photocatalytic property of titanium oxide crystals, the mesoporous sodium doped titanium dioxide (Na–TiO2) micro-nano powder was synthesized by the solid-state reaction (SSR) method, and characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectrum (UV–Vis), scanning electron microscopy/energy dispersive spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 desorption-adsorption. Meanwhile, the UV-degradation properties of Na–TiO2 and P25–TiO2 powder materials for hydroquinone (HQ) were studied. The results show that sodium ions with the low charge density entered into the (004) crystal place of anatase TiO2, producing the dislocation defects of TiO2 crystal structure. The spherical-like morphology micro-nanopowder with a size of 50–500 nm, sodium content of 3.36(wt%), the bandgap width of 3.08 eV, BET surface area of 111.52 m2/g, the pore size distribution center of 4.72 nm, the pore volume of 0.32 cm3/g are obtained, respectively. Within 60min and 25 °C, the UV-degradation rate (97.32%) of mesoporous Na–TiO2 powders for hydroquinone is 2.62 times for that (37.08%) of P25–TiO2 powder. It is mainly derived from the increase of dislocation density of Na–TiO2 powder, and the results of the synergistic photocatalystic degradation of hydroxyl radicals and superoxide radicals. And the photocatalytic efficiency is associated with pH value, photocatalyst dosage, concentration of HQ, irradiation time and stability.