title: Complex doping chemistry owing to Mn incorporation in nanocrystalline anatase TiO2 powders.
abstract: Mn-doped TiO2 powders with a wide range of nominal doping levels were fabricated using a one-step hydrothermal method followed by 400 °C annealing. Anatase powders with a uniform size distribution below 10 nm were obtained. The maximum solubility of Mn in the TiO2 lattice was around 30%, beyond which the Mn3O4 compound appeared as a secondary phase. The optical absorption edges for Mn-doped anatase TiO2 were red-shifted effectively through increasing Mn content. Alloying chemistry and associated elemental valences were elaborated through combining X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and theoretical simulation in the framework of density functional theory (DFT). The results showed that the Mn species exhibited mixed valence states of 3+ and 4+ in anatase TiO2, with the latter being the key to remarkable photocatalytic performance.
authors.affiliation: Institute for Renewable Energy and Environmental Technologies, University of Bolton, Bolton, BL3 5AB, UK. gs6@bolton.ac.uk and Faculty of Materials Science and Engineering, Hubei University, Wuhan, 430062, China. gaoyun@hubu.edu.cn.
authors.forename: Meilan
authors.initials: M
authors.lastname: Guo
authors.affiliation: Faculty of Materials Science and Engineering, Hubei University, Wuhan, 430062, China. gaoyun@hubu.edu.cn.
authors.forename: Yun
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Institute for Renewable Energy and Environmental Technologies, University of Bolton, Bolton, BL3 5AB, UK. gs6@bolton.ac.uk and UK-China Centre for Multifunctional Nanomaterials, Zhengzhou University, Henan 450001, China.
authors.forename: G
authors.initials: G
authors.lastname: Shao