Carbonized lotus leaf/ZnO/Au for enhanced synergistic mechanical and photocatalytic bactericidal activity under visible light irradiation.

Nowadays, bacterial resistance has continued to be a troublesome issue caused by the abuse of antibiotics, and it is the paramount difficulty in resolving the bacterial proliferation and infection. In this study, fresh lotus leaf was treated with Zn followed by sintered and modification with gold nanoparticles through the photoreduction process sequentially, and thus a composite of micro/nanostructured carbonized lotus leaf/ZnO/Au (C-LL/ZnO/Au) was obtained to explore its bactericidal properties. C-LL/ZnO/Au retained the papillary structure of fresh lotus leaf and showed great mechanical bactericidal performance and photocatalytic sterilization. The antibacterial rate of mechanical sterilization for C-LL/ZnO/Au amount to 79.5% in 30 min, 4.7 times of fresh lotus leaf's figure under the same conditions. Furthermore, in C-LL/ZnO/Au, the introduction of gold nanoparticles heightened light absorbance through localized surface plasmon resonance (LSPR) effect and separation efficiency of photogenerated electron-hole pairs, which showed improved photocatalytic sterilization than that of carbonized lotus leaf/ZnO (C-LL/ZnO). Carbonized lotus leaf/ZnO/Au exhibited prominent photocatalytic and mechanical synergistic antibacterial performance against E. coli: all the bacteria were inactivated within 30 min under visible light. The approach presented here could be applied to a variety of biomass materials, which holds a promising application potential in biomedical, public health and other fields.