Pure and Cobalt-Modified ZnO Nanostructures Prepared by a New Synthesis Route Applied to Environmental Remediation

Pure and cobalt-doped 3D ZnO were produced using the microwave (MW)- ultraviolet (UV)-visible (Vis) radiation-assisted hydrothermal method (MW-UV-Vis HM). Using experimental design, the effects of cobalt and UV-Vis radiation during the synthesis stage on the physicochemical properties of the materials were evaluated with different characterization techniques such as X-ray diffraction, scanning and transmission electron microscopy, diffuse reflectance, and electrochemistry. The presence of cobalt had a great influence on the reduction of charge donors in the ZnO matrix and had their photocatalytic properties improved when produced under the effect of UV-Vis radiation. The catalytic activity of the materials has been verified in important environmental remediation reactions, such as the electrochemical reduction of CO2 and the photocatalytic degradation of emerging pollutants. The results achieved in this study show competitive efficiency values for CO2 reduction (97%) and photocatalytic degradation (91%) of emerging pollutants in natural waters, illustrating the great versatility of the produced material in distinct applications.