Study on the Sterilization Performance of Photocatalysts Used in Indoor Air Purification

Abstract

In the past decade, the application of photocatalytic sterilization technology for indoor air disinfection has been extensively investigated. However, selecting suitable photocatalysts with high sterilization efficiency remains a challenge. By doping and incorporating metals, the bandgap can be narrowed, thereby avoiding the recombination of photogenerated charges. This study compares the photocatalytic sterilization performances of three commonly used photocatalysts (TiO₂–Ag, MnO₂–TiO₂, and MnO₂–CeO₂) in a controlled laboratory setting. The results demonstrated that TiO₂–Ag exhibited the best sterilization performance. Within 20 min, the concentration of Serratia marcescens (the test bacterium) decreased logarithmically with respect to ln3.78 under a light intensity of 640 W/m². During the bacterial inactivation process, Serratia marcescens is inactivated by the destruction of its cell membrane, which decreases its enzyme activity and releases its cell contents. This can be attributed to the efficient generation of reactive oxygen species (O₂•^– and •OH) and the thermal effect. Spectral regulation has the most significant impact on the sterilization efficiency of MnO₂–TiO₂, reducing the probability of photocatalytic materials being excited. A significance analysis indicated that light intensity, exposure duration, photocatalyst type, dilution of used photocatalysts, and spectral regulation substantially impact photocatalytic sterilization outcomes. Density functional theory (DFT) was used to elucidate the mechanism for the adsorption and catalysis of bacterial cell membranes at the atomic scale.