Microstructure and photocatalytic activity of SnO2:Bi3+ nanoparticles

SnO2:Bi3+ nanoparticles were synthesized by a one-step hydrothermal method. The influence of Bi3+ impurity concentrations on SnO2:Bi3+ samples was deeply investigated by studying the changes in size, morphology, and band gap width of SnO2:Bi3+ materials. In addition, the interaction between the SnO2 crystalline host and Bi3+ was studied in detail by several characterization techniques, such as SEM, XRD, UV–Vis, PL, and EPR. We also investigated the photocatalytic activity of the SnO2:Bi3+ nanoparticles by photodegrading methylene blue (MB), rhodamine B (RhB), and phenol under visible light. The photocatalytic efficiency of the SnO2:Bi3+ nanoparticles was higher than that of pure SnO2 nanoparticles. The photocatalytic degradation efficiency of SnO2:Bi3+-2% for MB was up to 52% and 15%–20% for the other samples. The photocatalytic degradation efficiency of SnO2:Bi3+-2% for RhB is up to 65% and that of the remaining samples is 25%–46%. The high degradation efficiency of the SnO2:Bi3+-2% sample was due to its small crystal size, which increased the specific surface area, resulting in higher photocatalytic efficiency. In addition, the high photocatalytic efficiency of the SnO2:Bi3+-2% sample is related to the defect states, increasing the surface charge carrier transfer rate and reducing the electron–hole recombination rate. Meanwhile, the photocatalytic efficiency of the SnO2:Bi3+ nanoparticles for phenol is 41% and 43% with SnO2:Bi3+-6% and −8% samples, respectively, and that of the remaining samples is 32%–34%. This finding is explained by the interaction between Bi3+ ions and phenol molecules, increasing the photocatalytic efficiency. This work increases the feasibility of degrading environmental pollutants using SnO2:Bi3+ photocatalysts with high efficiency.