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

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 mu m 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 degrees 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 center dot O-2(-) and photogenerated holes, and partly involved by (OH)-O-center dot. (C) 2013 Elsevier B.V. All rights reserved.