Effect of Cr Doping on Visible-Light-Driven Photocatalytic Activity of ZnO Nanoparticles

Visible-light response semiconductors have been recognized by many researchers as powerful photocatalysts due to their efficient utilization of solar energy. Herein, Cr-doped ZnO nanoparticles (Cr-ZnO NPs) with different Cr atomic percentages were synthesized via a facile sol-gel route and systematically investigated with respect to the photocatalytic degradation of recalcitrant organic contaminants under visible-light conditions. The crystal structure and morphology of materials were characterized by x-ray diffraction patterns and transmission electron microscopy. X-ray photoelectron spectroscopy was employed to confirm the presence of Cr3+ ions successfully incorporated into the ZnO lattice. UV-Vis diffuse reflectance spectroscopy and photoluminescence spectra revealed that Cr doping remarkably increased the absorption of ZnO NPs and charge carrier separation, resulting in improved photocatalytic degradation efficiency. In addition, a trapping experiment was conducted to identify the involvement of reactive radicals in the photocatalysis process, suggesting that photogenerated electrons play a predominant role in photocatalytic degradation of Cr-ZnO NPs. Graphic