Effects of silver ion doping on the surface defect characteristics of TiO2

Silver ion doping in the optimal content could enhance the photocatalytic activity of TiO2 nanoparticles greatly, which was concluded by the degradation of methyl orange in aqueous solution in the presence of TiO2 nanoparticles. X-ray diffraction (XRD) results suggested that the existence of silver ions increased the growth of TiO2 nanoparticles during calcinations. Detailed XRD investigation showed that silver ion doping caused a change in the parameters of the TiO2 lattice, which could be attributed to the O vacancies induced by substitutional metal ions with oxidation states less than 4. XPS measurements revealed the existence of Ti defects with reduced states in TiO2. The concentration of the reduced Ti defects was influenced by the doping content of silver ions, which should be an important factor for the change of the photocatalytic activity of TiO2.