Preparation of La2O3-modified BaSn Composite Nanorods and Photocatalytic Properties toward Crystal Violet

Background: The separation efficiency of the electron and hole pairs of the BaSn composite nanorods is limited due to a wide band gap energy restricting the photocatalytic treatment ability of the composite nanorods. It is an efficient route to improve the photocatalytic properties of the semiconductor photocatalysts by La2O3 modification. Objective: This study aims to synthesize La2O3-modified BaSn composite nanorods through a simple method and research the photocatalytic performance of the La2O3-modified BaSn composite nanorods for crystal violet degradation. Methods: La2O3 modified BaSn composite nanorods were synthesized by a facile method using lanthanum acetate as the lanthanum raw material and evaluated by electron microscopy, solid diffuse reflectance spectra, X-ray diffraction, photoluminescence and photocatalytic measurement for crystal violet degradation under ultraviolet light irradiation. Results: BaSn composite nanorods consist of orthorhombic SnO2, monoclinic BaSn(OH)6, and monoclinic Ba(OH)2. La2O3 suppresses the growth of the monoclinic BaSn(OH)6, and orthorhombic SnO2. The La2O3-modified BaSn composite nanorods possess coarse surface covered with the La2O3 nanoscale particles with an average size of about 50 nm. The absorption edge red-shifts to 373 nm and the band gap energy reaches 3.32 eV of the La2O3 modified BaSn composite nanorods compared with the BaSn composite nanorods. 20 mL 10 mg·L^-1 crystal violet solution can be entirely removed by 20 mg composite nanorods with 15wt.% La2O3 content under ultraviolet light irradiated for 120 min. The reaction rate constant is 2.4 times higher than that of the non-modified composite nanorods. Hydroxyl radicals and holes are the reaction active substances for crystal violet degradation in the composite nanorod reaction system. Conclusion: La2O3 modification decreases the band gap energy, enhances the light absorption ability, and suppresses the recombination of the electron and hole pairs of the composite nanorods.