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

Abstract

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 O3. 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 O3 concentration from 0.38 to 0.04 ppm, whereas the presence of TiO2 reduces the sterilization efficiency and O3 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 O3. 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.