Flower-like SnO2/Sn3O4 Microspheres with Heterojunction: Fabrication by Ti4+-Doping and Photocatalytic Performance

The flower. like Sn3O4 and x% Ti-SnO2/Sn3O4 (x% was the molar ratio of Ti to Sn) microspheres stacked by the layered nanosheets were prepared by the hydrothermal method. The synthesized samples were analyzed by phys. ical and chemical methods, e. g., X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, infrared spectroscopy, and photocurrent response. The results show that because ion radius of Ti4+ is similar to Sn4+, it can enter the Sn3O4 lattice instead of Sn4+ to form alternative dopants. At the same time, the doping of Ti4+ makes a part of Sn4+ directly combine with oxygen to form nano.spherical SnO2 dispersed over the surface of Sn3O4, forming a SnO2/Sn3O4 heterojunction. The photocatalytic activity test shows that x% Ti-SnO2/Sn3O4 not only has the ability to reduce Cr6+, but also has the ability to degrade methyl orange and acid orange II. The enhanced catalytic activity is attributed to the surface area and light absorption of x% Ti-SnO2/Sn3O4. Moreover, the produced SnO2/Sn3O4 heterojunction can effectively promote the separation efficiency of photo.generated electrons and holes.