Preparation And Antibacterial Mechanism Of ZnO@SiO₂ Composite Antibacterial Materials

Because of better exciton ability,high photosensitivity,nontoxicity and low cost,zinc oxide(ZnO)has been recognized as one of the promising photocatalytic materials.However,ZnO as photocatalyst has a low light absorption which limits the application range owing to its wide band gap.Sc/ZnO supported on silica surface was prepared by the direct co-precipitation method,and the material structure was analyzed by experimental characterization and density functional theory(DFT).The innovative research results obtained are as follows:First,the monomer addition model of the hydrolysis condensation process was established through an experimental study on the hydrolysis reaction of tetraethyl orthosilicate(TEOS)with the miniemulsion.These data correspond to the results of one experiment.According to the above model,the reaction was adjusted to make the number of hydroxyl groups(-OH)on the surface of Si O₂ close to the theoretical value.At the same time,it was found that the hydrolysis reaction of the monomer addition model was extremely fast,and the condensation rate between silicic acid(Si(OH)₄)was relatively slow.It is clearly demonstrated that the condensation reaction between Si(OH)₄ accelerates with the increase in amount of TEOS,while the H₂O,NH₃·H₂O and temperature variables have obvious impacts on the hydrolysis process.Second,the Sc-doped ZnO samples were prepared by a cheaper doping technique,and the effects of the doping process on its structure and physical pr operties were studied by XRD and TEM.Data revealed that Sc doping did markedly increase the visible-light-responsive photocatalysis.By testing the antibacterial properties of doped samples against S.aureus and E.coli under natural light conditions,the effects of different preparation conditions on antibacterial properties were explored.The results show that Sc doping can increase the antibacterial activity of ZnO samples,and the sterilization rate of S.aureus enhanced from 81.6%to 99.99%,and the sterilization rate of E.coli increased from 88.4%to 99.99%.Third,quantum chemical calculations based on density functional theory(DFT)had investigated the mechanism of high-efficiency photocatalytic properties of hybrid materials.The results confirmed that Sc entering the ZnO lattice could be effective in delay electron-hole recombination,thereby increasing the lifetime of the photoelectrons on the material surface.In the meantime,the hybrid material containing oxygen vacancy(Vo)can enhance the mi gration rate of electron.The results of the study indicated that strengthening effect of composite materials on catalytic conversion of different bacteria,and provide new ideas for the design of new"honeycomb ceramics"in the air clean system and the treatment of waste liquid containing organic pollutants.