Superlattice Nanofilm on a Touchscreen for Photoexcited Bacteria and Virus Killing by Tuning Electronic Defects in the Heterointerface

Currently, the global COVID-19 pandemic has significantly increased the public attention toward the spread of pathogenic viruses and bacteria on various high-frequency touch surfaces. Developing a self-disinfecting coating on a touchscreen is an urgent and meaningful task. Superlattice materials are among the most promising photocatalysts owing to their efficient charge transfer in abundant heterointerfaces. However, excess electronic defects at the heterointerfaces result in the loss of substantial amounts of photogenerated charge carrier. In this study, a ZnOFe₂ O₃ superlattice nanofilm is designed via atomic layer deposition for photocatalytic bactericidal and virucidal touchscreen. Additionally, electronic defects in the superlattice heterointerface are engineered. Photogenerated electrons and holes will be rapidly separated and transferred into ZnO and Fe₂ O₃ across the heterointerfaces owing to the formation of ZnO, FeO, and ZnFe covalent bonds at the heterointerfaces, where ZnO and Fe₂ O₃ function as electronic donors and receptors, respectively. The high generation capacity of reactive oxygen species results in a high antibacterial and antiviral efficacy (>90%) even against drug-resistant bacteria and H1N1 viruses under simulated solar or low-power LED light irradiation. Meanwhile, this superlattice nanofilm on a touchscreen shows excellent light transmission (>90%), abrasion resistance (10⁶ times the round-trip friction), and biocompatibility.