Rapid synthesis of Zn2+ doped SnWO4 nanowires with the aim of exploring doping effects on highly enhanced visible photocatalytic activities

In this work, we report on the rapid synthesis of Sn1−xZnxWO4 nanocrystals with the aim of tailoring their structural, electronic, and photocatalytic properties. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, inductive coupled plasma optical emission spectroscopy, UV-vis diffuse reflectance spectroscopy, and the Barrett–Emmett–Teller technique. The effects of Zn2+ doping in SnWO4 on the electronic structure and photogradation of methylene orange dye solution were investigated experimentally and theoretically. It was found that Zn2+ ions were homogeneously incorporated into the SnWO4 host lattice with a solubility of x = 0.060, which led to a monotonous decrease in lattice volume. With Zn2+ doping, SnWO4 nanocrystals showed a morphological alteration from irregular nanosheets to nanowires. Meanwhile, the BET surface areas were also greatly enlarged from 54 m2 g−1 to ∼100 m2 g−1. Contrary to the theoretical predictions of the quantum size effect, Zn2+ doped SnWO4 nanocrystals showed an abnormal band gap narrowing, which can be well-defined as a consequence of the balance of quantum size effect, lattice contraction, electronegativity, and surface defect centers. With well-controlled morphology, surface area, and electronic structure via Zn2+ doping, the photocatalytic performance of Sn1−xZnxWO4 nanocrystals was optimized at a Zn2+ doping level of x = 0.045.