Electronic, optical and photocatalytic behavior of Mn, N doped and co-doped TiO sub(2): Experiment and simulation

The crystal phase structure, surface morphology, chemical states and optical properties of Mn, N mono-doped and co-doped TiO sub(2) nanoparticles were investigated by X-ray powder diffractometry, Raman spectra, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. Meanwhile, geometry structures, formation energies, electronic and optical properties of all systems have been also analyzed by density functional theory. The results showed that the band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO sub(2). The number and the carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light. Especially, the photocatalytic activity of Mn-2N co-doped TiO sub(2) beyond three-fold than that of pure TiO sub(2) under visible-light. The ILs formed by N-2p orbital in N single doped specimen lie above the VB, while the ILs formed by Mn-3d orbital in Mn single doped specimen appear below the CB. However, a large amount of ILs formed by N-2p orbital and Mn-3d orbital in N and Mn codoped specimens. The band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO sub(2). The number and the carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light.