Indium doping in sol-gel synthesis of In-Sm co-doped x In-0.05%Sm-TiO ₂ composite photocatalyst

Abstract Sol-gel method was used to prepare a novel In-Sm co-doped TiO ₂ photocatalyst. The materials were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared/far infrared, UV-Vis diffuse reflectance, and N ₂ adsorption-desorption analyses. Anatase phase TiO ₂ is formed in the pure and doped TiO ₂ samples. Anatase TiO ₂ crystal formation and growing are disturbed by the dopants. The substitution of smaller Ti ⁴⁺ ions by the larger Sm ³⁺ and In ³⁺ ions causes the expansion of TiO ₂ cell. The doping of indium and samarium ions has no noticeable influence on the bonding characters of TiO ₂ . A continuous red shift of the absorption edge of x In-0.05%Sm-TiO ₂ occurs at increasing indium doping content. Brunauer-Emmett-Teller surface area, average pore size, and total pore volume are enhanced after doping of samarium and indium. The adsorption of methyl orange on the surface of x In-0.05%Sm-TiO ₂ increases with rising indium content. The 5%In-0.05%Sm-TiO ₂ has the maximum photocatalytic activity. About 97.7% of the initial methyl orange is decolorized on 5%In-0.05%Sm-TiO ₂ after 45 min of irradiation.