La and Cr co-doped SrTiO3 prepared by citric-combustion method for photocatalytic degradation of antibiotics under visible-light

The problem of antibiotic contamination has received increasing attention, and photocatalytic degradation is considered to be an effective solution. In this paper, a series of La, Cr co-doped SrTiO3 nanoparticles (La0.0xSr1−0.0xTi1−0.0xCr0.0xO3, denoted as STO-x) were synthesized using a simple citric-combustion method. X-ray diffraction pattern shows that all samples form a cubic perovskite structure, with a shift in the characteristic peak for the doped samples. The UV–Vis diffuse reflectance spectroscopy studies reveal that all Cr-doped samples have strong absorption of visible light. STO-1 has the largest specific surface area of 22.49 m2/g and the lowest photoluminescence intensity. More attractively, according to the X-ray photoelectron spectroscopy, the largest Cr3+/Cr6+ molar ratio is found in the STO-1 sample. The photocatalytic investigation demonstrates the significant photocatalytic activity of the doped samples for the degradation of tetracycline and ciprofloxacin under visible light, with STO-1 showing the best performance. Further, the mechanism of enhanced photocatalytic activity of La, Cr co-doped SrTiO3 samples is studied by trapping experiments. Therefore, this work shows that La, Cr ion co-doping is an effective method to improve the visible photocatalytic performance of SrTiO3.