The Photocatalytic and Antibacterial Activity of Copper-doped Titanium Dioxide Nanoparticles

Abstract

Organic pollutants and pathogenic microbes exist in water systems causing many communities, especially in developing countries, to have a high risk of infection with water-borne diseases. Developing a simple, cost-effective, and efficient sunlight-driven water treatment technology is crucial for people to access clean and safe water. The most widely studied photoactive and antibacterial material is titanium dioxide (TiO2) nanoparticles (NPs). TiO2 NPs can produce highly reactive free radicals to oxidize organic pollutants and deactivate biological pollutants. However, pristine TiO2 NPs have a large band gap and only harvest solar radiation in the UV region. This thesis focuses on developing copper-doped titanium dioxide (TiCuxO2) catalysts and exploring its photocatalytic activity in the visible-light region. The first project focuses on synthesizing Cu-doped white TiO2 (wTiCuxO2) NPs using the solvothermal approach. The second project is a comprehensive study on Cu-doped black TiO2 (bTiCuxO2) NPs. The photocatalytic performance of the resulting TiCuxO2 catalysts (white and black particles) were evaluated using degradation of Rhodamine B (RhB) dye and disinfection of Escherichia coli (E. coli) under visible light irradiation. We show that introducing a Cu dopant and surface defects on the catalysts enhances its photodegradation ability. The mechanism of increased photocatalytic activity for TiCuxO2 is hypothesized to be due to band gap narrowing and accelerated charge separation. For disinfection ability, the activity might be related to the free Cu ions increasing the radical species under irradiation. In the project, I have developed two efficient photocatalysts for water treatment; the mechanistic studies of the nano-catalysts increase our understanding of the heterogeneous catalysts for photo-degradation of industrial dyes and inactivation of waterborne microbes, which are useful for engineering more efficient and sustainable water treatment devices.