Photocatalytic Activity and Antibacterial Properties of ZnO/CNTs Composites

Photocatalytic technology is one of the promising technologies for wastewater treatment. Herein, zinc oxide/multi-walled carbon nanotubes (ZnO/CNTs) photocatalyst was successfully prepared by hydrothermal method with combining in-situ synthesis technology. The micro-morphology, crystalline structure, surface chemical elements, and optical properties were characterized by SEM, TEM, XRD, FTIR, UV-Vis, and DRS technologies. The ZnO/CNTs photo-catalyst exhibited enhancement photo activity for degradation of organic pollutants under simulated light irradiation. Specifically, the photo-catalytic activity of the ZnO/CNTs catalysts improved with the rise of CNTs content in the composites. Investigation on the photo-degradation mechanism verified that the presence of CNTs in the catalyst not only optimized the band structure of ZnO semiconductor but also contributed to the transfer of photo-generated electrons and reducing the recombination of electron-hole pairs due to its excellent conductivity. Moreover, the active radical groups such as superoxide radical (O-2), hole (h+), and hydroxyl radical (·OH) played the dominated role for the pollutants degradation under the simulated sunlight irradiation. In addition, ZCT20 catalysts and light irradiation had synergistic effects on antibacterial activity, whose antibacterial rates against E. coli and S. aureus were up to 99.96% and 99.94%, respectively. Investigation on antibacterial mechanisms revealed that the existence of ROS and the continuous release of Zn2+ played an important role for improving the antibacterial activity of the ZCT20 catalyst under the simulated sunlight irradiation.