Enhanced optical absorption and photocatalytic activity of Cu/N-codoped TiO2 nanocrystals

Cu/N-codoped TiO2 nanoparticles were prepared by sol–gel technique. Their structure, surface chemical composition, and optical absorption were characterized. All as-prepared samples consisted of the anatase phase. It was found that Cu atoms replaced Ti atom sites, and N atoms occupied the O atom sites and interstitial sites in the TiO2 lattice. The optical absorption results reveal that Cu/N codoping could greatly enhance the absorption of TiO2 in the entire visible region, leading to a decrease in the band-gap energy of TiO2. It also significantly enhanced the solar-driven catalytic activity of TiO2 in the degradation of methylene blue in solution. The sample 2.0 at% Cu/N-codoped TiO2 displayed the highest solar-driven catalytic efficiency among all tested samples.