Er-W codoping of TiO2-anatase: structural and electronic characterization and disinfection capability upon UV, visible, and near-IR excitation

Abstract

The codoping of the anatase structure with tungsten and erbium was carried out using a microemulsion preparation procedure. Tungsten and erbium single doped and pure anatase nanomaterials were also prepared. The corresponding solids were characterized using X-ray diffraction, surface area, transmission electron microscopy, X-ray photoelectron and absorption (X-ray near-edge and extended X-ray absorption) spectroscopies as well as UV–vis and photoluminescence spectroscopies. Results provided a complete structural and electronic characterization of the solids, showing the unique features generated by the copresence of tungsten and erbium at substitutional positions of the anatase structure. The disinfection capability of these single and codoped TiO2-based materials was tested against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria and under ultraviolet, visible and near infrared light excitations. The ErW-anatase solid presents significant photoactivity in the elimination of both microorganisms in the whole UV–vis-nearIR range of excitation wavelengths. The biocidal results were interpreted with the help of a kinetic modelling of the experiments and correlated with results from the physico-chemical characterization of the samples and from an electron paramagnetic resonance and optical study of the radicals species produced under illumination. This procedure indicates a different physical origin of the photoactivity for light excitation above and below ca. 500 nm.