Photocatalytic Activity and Antibacterial Behavior of Fe³⁺-Doped TiO₂/SnO₂ Nanoparticles

Problem statement: Since bacteria mainly causes damage on fresh vegetables and fruits during transportation to market, anti-bacterial TiO₂ photocatalyst was applied for their packaging films. However, it has been known that pure TiO₂ exhibits low photocatalytic property due to rapid recombination of photo-activated electrons and holes. Doping with metal or metal oxide shows the improvement of photocatalytic activity and disinfection effect. Approach: Fe³⁺ was considered to dope into TiO₂/3SnO₂ photocatalyst in order to enhance the photocatalytic property and bacterial inactivation efficiency. The Fe³⁺ doped TiO₂/3SnO₂ nanoparticles were prepared by sol-gel method and calcined at 400 °C for 2 h. The synthesized powders were characterized by XRD, BET and SEM. Photocatalytic activity and bacteria killing effect were determined by means of degradation of methylene blue solution and inactivation of E. coli bacteria, respectively. These tests were performed under UV and visible light irradiations. Results: Fe³⁺ doping into TiO₂/3SnO₂ has an effect on inhibition of anatase crystal growth, led to the enlargement of the composite specific surface area. Therefore, the photocatalytic activity of Fe³⁺ doped TiO₂/3SnO₂ composite in proper concentration was greater than those of pure TiO₂ and TiO₂/3SnO₂ and 0.5 mol% Fe³⁺ doping exhibited the highest photocatalytic activity and E.coli inactivation efficiency. The E. coli was completely killed within 90 min under UV irradiation or 99.7% inactivated under visible light exposure. Conclusion: Fe³⁺ doped TiO₂/3SnO₂ nanoparticles were successfully synthesized and identified as 100% anatase phase. The 0.5mol% Fe3+-doped TiO2/3SnO2 which has particle size of 12.89 μm and specific surface area of 117.61 m² g^-1, exhibited the highest activity and disinfection efficiency. An attractive feature of Fe³⁺ doped TiO₂/3SnO₂ photocatalytic disinfection is its potential to be activated by visible light. Therefore, these composite TiO₂ nanoparticles can be utilized for fresh food packaging films.