Improving plasma sterilization by constructing a plasma photocatalytic system with a needle array corona discharge and Au plasmonic nanocatalyst

Efficient sterilization by a plasma photocatalytic system (PPS) requires strong synergy between plasma and photocatalyst to inactivate microorganisms while suppressing the formation of secondary pollutants. Here, we report that a PPS constructed from a needle array corona discharge and Au/TiO2 plasmonic nanocatalyst could remarkably improve the sterilization of Escherichia coli (E. coli) and alleviate formation of the discharge pollutant O-3. At 6 kV, the combination of corona discharge and Au/TiO2 achieves sterilization efficiency of 100% within an exposure time of 5 min. At 5 kV and an exposure time of 8 min, the presence of Au/TiO2 improves sterilization efficiency of the corona discharge from 73% to 91% and reduces the O-3 concentration from 0.38 to 0.04 ppm, whereas the presence of TiO2 reduces the sterilization efficiency and O-3 concentration to 66% and 0.17 ppm, respectively. The Au/TiO2 in the PPS enables a uniform corona discharge, enhances the interaction between plasma, E. coli and nanocatalysts, and suppresses the formation of O-3. Further, the Au/TiO2 can be excited by ultraviolet-visible light emitted from the plasma to generate electron-hole pairs, and thus contributes to the formation of reactive radicals and the oxidative inactivation of E. coli. The PPS constructed from a needle array corona discharge and Au-based plasmonic nanocatalyst provides a promising approach for developing high-efficiency sterilization techniques.