The enhanced near-infrared photocatalytic and photothermal effects of MXene-based heterojunction for rapid bacteria-killing

Bacterial resistance threatens the health of human beings when they combat pathogenic diseases with antibiotics. Herein, an ecofriendly and antibiotics-free 0D/2D Schottky heterojunction (Ag2S/Ti3C2) was synthesized for the first time to treat bacterial infection with a high efficacy of 99.99% within 20 min under 808 nm NIR light irradiation, which was ascribed to the synergy of enhanced photocatalytic and photothermal effects. The density functional theory calculations show that when a redistribution of charge occurs at the interface between Ag2S and Ti3C2 due to the difference in their Fermi energy levels (EF), it results in an upward bend of the Ag2S energy band. Additionally, in the case of Ag2S/Ti3C2, the higher conduction band energy of Ag2S compared to the EF of Ti3C2 and the excellent electrical conductivity of the latter made the photoexcited electrons in Ag2S, including those hot electrons produced by surface plasma resonance (SPR), rapidly flow to Ti3C2, thus greatly increasing both photocatalytic and photothermal performance of Ti3C2. In vitro and in vivo tests showed that this photoresponsive system possessed not only highly effective antibacterial efficacy against Staphylococcus aureus infection but also excellent biocompatibility simultaneously. Therefore, this hybrid is expected to be a promising ecofriendly platform for the rapid treatment of bacterial infections using NIR light.