Tunning the bandgap of MnO2 homojunction by building active high-index facet to achieve rapid electron transfer for enhanced photocatalytic sterilization

Photocatalysis has been a research hotspot in recent years, and the design and modification of photocatalysts have been the key points. Common methods for designing photocatalysts, including constructing heterojunctions and homojunctions, have been developed on the basis of heterojunctions. In this study, two homojunctions of manganese dioxide (MnO2), including a high-index crystal plane homojunction and a general homojunction, are prepared using a stepwise hydrothermal method. Using a capping agent, the high-index crystal surface of the MnO2 is exposed. It is found that the electron transport efficiency between the two components of the homojunction with high-index planes is higher and the adsorption capacity of the oxygen is stronger, which leads to higher photocatalytic efficiency. In addition, the newly designed high-index homojunction is used for the treatment of bacterial infections, and it kills Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) at rates of 99.95% ± 0.04% and 99.31% ± 0.25%, respectively. It also has excellent therapeutic effects on mouse wounds, which implies superb practical application value. This work provides a new strategy for the improved design of homojunctions and the application of photocatalytic materials.