Photocatalytic removal of NO and HCHO over nanocrystalline Zn2SnO4 microcubes for indoor air purification

Nanocrystalline Zn2SnO4 microcubes were hydrothermally synthesized and systematically characterized by XRD, SEM, TEM, XPS, N2 adsorption-desorption, and UV-vis DRS analysis. The resulting Zn2SnO4 microcubes with the edge size ranging from 0.8 to 1.2 μm were composed of numerous nanoparticles with size of 10-20 nm, and their optical band gap energy was estimated to be 3.25 eV from the UV-vis diffuse reflectance spectra. On degradation of nitrogen monoxide (NO) and formaldehyde (HCHO) at typical concentrations for indoor air quality, these nanocrystalline Zn2SnO4 microcubes exhibited superior photocatalytic activity to the hydrothermally synthesized ZnO, SnO2, and Degussa TiO2 P25, as well as C doped TiO2 under UV-vis light irradiation. This enhanced photocatalytic activity of the nanocrystalline Zn2SnO4 microcubes was attributed to their bigger surface areas, smaller particle size, special porous structures, and special electronic configuration. The nanocrystalline Zn2SnO4 microcubes were chemically stable as there was no obvious deactivation during the multiple photocatalytic reactions. This work presents a promising approach for scaling-up industrial production of Zn2SnO4 nanostructures and suggests that the synthesized nanocrystalline Zn2SnO4 microcubes are promising photocatalysts for indoor air purification.