Facile fabrication of porous ZnO by thermal treatment of zeolitic imidazolate framework-8 and its photocatalytic activity

► Porous ZnO powders can be obtained by thermal decomposition of ZIF-8. ► The morphology, structure and performance of porous ZnO can be controlled. ► ZnO-500-5 exhibits efficient photocatalytic activity for the degradation of MB. In this work, porous ZnO photocatalysts were attempted to be prepared by a facile method, i.e. the thermal treatment of zeolitic imidazolate framework-8, and then characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy and nitrogen adsorption–desorption. It was found that the calcination temperature and time significantly influenced the morphology, composition and pore structure of ZnO. The photocatalytic activities of as-prepared ZnO powders were evaluated in the degradation of methylene blue (MB) under UV light in comparison with commercial anatase TiO2 and Degussa P25 TiO2. The surface area and crystallinity of porous ZnO obviously affected the photocatalytic activity of ZnO. The ZnO prepared at 500°C for 5h (ZnO-500-5) showed the highest photocatalytic activity, which was higher than that of the commercial anatase TiO2 and lower than that of Degussa P25 TiO2.