Metal oxide composite thin films made by magnetron sputtering for bactericidal application

To broaden the application of antibacterial catalysts, ZnO/Ag₂O composite thin films with different Ag₂O contents have been successfully synthesized on non-woven fabric at room temperature by radio frequency (RF) sputtering with a single ceramic target formed by hot pressing ZnO/Ag₂O nanocomposite powder in Ar atmosphere at 180 °C for 30 min. The composite thin films were also sputtered on glass substrates for characterizations. The best sputtering condition was found with the Ar/O₂ gas flow ratio at 7:1 to obtain pure Ag₂O thin film. The deposition of Ag₂O nanoparticles on commercially available ZnO particles was also confirmed by HR-TEM prior to hot pressing for synthesizing ceramic targets. In this work, an appropriate amount of Ag₂O incorporated in the composite film was endeavored by forming p–n junction to lower the cost without decreasing bactericidal ability of composite film. The amount of 45 wt% Ag₂O in composite thin film to provide bactericidal effect was found to be as good as pure Ag₂O. The feasibility in bactericide is due to the light sensitization of low bandgap Ag₂O and the formation of nano p–n heterojunction between p-type Ag₂O and n-type ZnO for efficient photo carrier separation. The dependence of antibacterial effect of ZnO/Ag₂O thin films on the Ag₂O content is demonstrated and elucidated in this work.