Photocatalytic antimicrobial and photostability studies of TiO2/ZnO thin films

Abstract

A nanothin film-based antimicrobial coating has been attractive in response to the rise and spread of pathogenic microbes, which led to the development of low-cost, effective, and rapid disinfection methods for coating material. TiO2/ZnO bilayer thin films have been developed through magnetron sputtering and thermal oxidation. The influence of oxidation temperature on structural, optical, photocatalytic, photostability, and antimicrobial properties of Ti/ZnO thin films has been addressed. X-ray diffraction (XRD) analysis has shown the presence of hexagonal wurtzite ZnO, Ti0.895O.77, and anatase TiO2 in the bilayer films. Increasing the oxidation temperature reveals a certain degree of crystallization and transforms Ti0.895O.77 into the anatase/rutile TiO2 phase. The bottom layer of ZnO provides sufficient oxygen to improve TiO2 crystallinity and prevent transforming anatase to rutile during thermal oxidation process. Moreover, Ti/ZnO thermally oxidized at 550 °C exhibit excellent photocatalytic performance under UV irradiation with high photostability. The inhibition rate increased (p < 0.05) with irradiation time for E. coli, S. aureus, and C. albicans with effectiveness values reaching approximately 97 ± 3.408, 98 ± 2.409, and 95 ± 3.105 %, respectively. This work reveals that magnetron sputtering through a thermal oxidation approach could generate stellar TiO2/ZnO thin films as photocatalysts and antimicrobial agents with cost-effectiveness and efficiency.

Keywords

• Antimicrobial coating
• Thermal Oxidation
• TiO2/ZnO thin films
• Irradiation time