Evaluation of photocatalysis inactivation in indoor air purification of pathogenic microbes by using the different nanomaterials based on TiO2 nanomaterials.

The photocatalytic technology for indoor air disinfection has been broadly studied in the last decade. Selecting proper photocatalysts with high disinfection efficiency remains to be a challenge. By doping with the incorporation of metals, the bandgap can be narrowed while avoiding the recombination of photogenerated charge. Three photocatalysts (Ag-TiO₂, MnO₂-TiO₂, and MnS₂-TiO₂) were tested in photocatalytic sterilization process. The results revealed that Ag-TiO₂ had the best antibacterial performance. Within 20 min, the concentration of Serratia marcescens (the tested bacteria) decreased log number of ln 4.04 under 640 w/m² light intensity with 1000 µg/mL of Ag-TiO₂. During the process of inactivating bacteria, the cell membranes of bacterial was destructed and thus decreasing the activity of enzymes and releasing the cell contents, due to the generation of reactive oxygen species (O₂•^- and •OH) and thermal effect. Spectral regulation has the greatest impact on the sterilization efficiency of MnO₂-TiO₂, which reduces the probability of photocatalytic materials being excited.