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.

Keywords:
microwave synthesis; photocatalysis; CO₂ reduction; emerging pollutants; environmental remediation; chemometrics