Facile template-free one-pot fabrication of ZnCo2O4 microspheres with enhanced photocatalytic activities under visible-light illumination

•ZnCo2O4 microspheres were prepared through a solvothermal reaction.•The photocatalytic degradation activity is higher than that of N–TiO2 and P25 TiO2.•The main oxidative species in the photocatalytic process are O2 and OH.

A spinel photocatalyst, ZnCo2O4 hierarchical microspheres assembled by nanosheets, was fabricated by a facile template-free one-pot solvothermal reaction for the first time, and characterized by the methods of X-ray diffraction(XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy(DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area measurements, exhibited efficient photocatalytic activity in the degradation of organic pollutant under visible-light irradiation. The as-prepared microspheres with the diameter of about 5 μm were assembled of nanosheets with the thickness of about 20 nm, and those nanosheets stack together tightly to form 3-D hierarchical framework among them. The photocatalytic degradation rate of methylene blue onto the ZnCo2O4 from solvothermal reaction at 180 °C was higher than that of N–TiO2. The adsorptive isotherm indicated that monolayer adsorption was existed between photocatalyst surface and organic pollutants. The main oxidative species in the photocatalytic process could be attributed to be O2- and photogenerated holes, and partly involved by OH.