Doped Titanium Oxide Photcatalysts: Preparation, Structure and Interaction With Viruses

Abstract

In this study, both chemical and physical modification approaches were developed to extend the absorption band-edge of TiO2 into the visible light region with improved stability, photocatalytic efficiency and ease of the doping process. Two major approaches were used in the material synthesis and processing, including the ion-beam-assisted-deposition (IBAD) technique and sol-gel based processes. Both nitrogen-doped TiO2 (TiON) and nitrogen/palladium co-doped TiO2 (TiON/PdO) photocatalysts were created and their photocatalytic activity was investigated by the degradation of methylene blue (MB) and disinfection of bacteria and viruses under visible light illumination. The sol-gel process was optimized to produce high quality TiON-based photocatalysts by carefully modulating the precursor ratio and calcination temperature. A TiON inverse opal structure was created, which demonstrated enhanced visible light absorption and subsequently improved photocatalytic efficiency by the combination of chemical and physical modifications on n-TiO2. The effect of palladium dopant on the optical and photocatalytic properties of TiON/PdO photocatalyst was examined, which suggests that a careful optimization of the transition metal ion dopant concentration is needed to achieve high photocatalytic efficiency in these anion and transition metal ion co-doped TiO2 photocatalysts. High photocatalytic virus disinfection efficiency under visible-light illumination was observed for the first time with TiON/PdO photocatalyst, and the interaction between MS2 virus and TiO2-based semiconductor surfaces was successfully modulated. A strategy to use atomic force microscope (AFM) to conduct in-situ observation of viruses on semiconductor surfaces in aqueous environment was developed, which combines information from both height profile and phase profile and solves the difficulty of observing small nanosized biomolecules on substrates with similar feature sizes.