Investigation Of High Efficient Composite RE-doped Photocatalytic Antibacterial Material

TiO₂ film is considered to be the most suitable photocatalytic antibacterial materials in future since health is a permanent issue for human being. However, this material has some disadvantages such as the poor utilization ratio of sunlight and little antibacterial activity without illumination. Therefore, in this paper, high efficient composite RE-doped TiO₂ photocatalytic antibacterial materials were investigated.RE-doped TiO₂ photocatalytic antibacterial films(La/TiO₂, Ce/TiO₂, Pr/TiO₂, Nd/TiO₂, Sm/TiO₂, Eu/TiO₂, Gd/TiO₂, Dy/TiO₂, Ho/TiO₂, Y/TiO₂) and Ag/Ce/TiO₂ composite photocatalytic antibacterial films were prepared by sol-gel method combined with spin coating method, meanwhile choosing E. coli, S. aureus, K. pneumoniae as experimental culture, fluorescent lamp and sunlight as light source, the effects of various factors on the antibacterial activity, e.g. the ultrasonic wave time, spin speeding, titrating height, sintering process, sintering temperature, sintering time, doped amounts and the number of coating layers were investigated by bactericidal rate. XRD, SEM and TG-DSC were adopted to characterize the thin films. UV-Visible spectrometer was used to analyze the UV-Visible absorption spectra of materials. TEM was performed to observe the antibacterial process of Ce/TiO₂ and Ag/Ce/TiO₂ film, the corresponding antibacterial mechanism was preliminary investigated.The results show that the structures of all RE/TiO₂ films and Ag/Ce/TiO₂ film were made up of anatase, except of Ce/TiO₂ which has less rutile. UV-Visible absorption spectra indicates that rare-earth doping evidently extends the response of photocatalytic materials to visible light, accordingly RE/TiO₂ and Ag/Ce/TiO₂ films have excellent antibacterial activity even under fluorescent lamp since their average bactericidal rate to selected bacteria were all above 90%. Among these photocatalytic antibacterial films the bactericidal rates to E. coli(5×10³cfu/ml) of Ce/TiO₂, Sm/TiO₂, Y/TiO₂ and Ag/Ce/TiO₂ can reach 91.3%, 91.1%, 90% and 92.8% respectively when the films were placed under sunlight in room.TEM indicates that the antibacterial mechanism of Ce/TiO₂ and Ag/Ce/TiO₂ was similar: electron, hole and highly oxidative species photoinduced in photocalytic reaction can destroy the cell wall, cytoplasmic membrane and inclusion, making the bacteria distorted, eventually inducing the death of the bacteria with the disruption of cell wall, the loss and decomposition of content. However the bactericidal rate of Ag/Ce/TiO₂ film, which combined the antibacterial mechanism of TiO₂ and silver, was faster than that of Ce/TiO₂...