Sol-gel synthesize and characterization of χGd2Ti2O7/SiO2 photocatalyst for ofloxacin decomposition

Highlights: • The surface of SiO₂ sphere is coated with a rough layer of Gd₂Ti₂O₇. • Many physico-chemical properties of Gd₂Ti₂O₇ are modified to enhance its activity. • The 30%Gd₂Ti₂O₇/SiO₂ sample has the optimal photocatalytic activity. - Abstract: Gd₂Ti₂O₇ was loaded on the surface of quartz spheres by a sol-gel method. The Gd₂Ti₂O₇ maintains the pyrochlore phase after loading. Dispersion of Gd₂Ti₂O₇ on the SiO₂ spheres reduces crystallite size of Gd₂Ti₂O₇. The surface of SiO₂ sphere is coated with a rough layer of Gd₂Ti₂O₇. The band gap energy of the χGd₂Ti₂O₇/SiO₂ constantly increases with decreasing Gd₂Ti₂O₇ loading content, ranging from 3.35 eV to 3.71 eV. The porous structure in the χGd₂Ti₂O₇/SiO₂ composite mainly comes from the Gd₂Ti₂O₇ layer. The maximum BET surface area and total pore volume are even larger than that of the unloaded Gd₂Ti₂O₇. The hydroxyl radical generation efficiency during illumination is enhanced after loading Gd₂Ti₂O₇ on SiO₂. The 30%Gd₂Ti₂O₇/SiO₂ sample has the optimal photocatalytic activity. 65.6% of the initial ofloxacin can be decomposed on 30%Gd₂Ti₂O₇/SiO₂ after 30 min of UV light irradiation, as compared to 24.1% on the unloaded Gd₂Ti₂O₇.