Researching The Electronic And Photocatalytic Properties Of ?Ta,Mn,Fe,Co?-?C,N,H? Co-doping TiO₂: Simulation And Experiment

The photocatalyst TiO₂ has been studied widely due to its superior efficient properties,such as inexpensive,chemically stable,non-toxic and high catalytic activity.However,its practical application has been limited by its large intrinsic band gap and high recombination rate of electron-hole pairs.Thus,it is of great importance to enhance the utilization rate of visible light and inhibition of light carrier compound.The details are as follows:?1?Bond relaxation and associated with the electronic energy can be modulating the properties of the substance.Doping is an effective way to reach such purpose.With the aid of first principle calculations and experimental observations,we examine four co-doped specimens?Ta�N¹,Ta�N²,Ta�N³,Ta�N⁴?with different Ta and N co-doped positions,and show that Ta or N addition could modulate the electronic,optical and photocatalytic responses of TiO₂ for photocatalysts applications.Results show that,Ta�O bonding not only reduces the electronic transition energies but also increased the carrier mobility of impurity level in Ta-doped and Ta�N²,Ta�N³,and Ta�N⁴ co-doped TiO₂ specimens,while the impurity level disappears and the band gap reduces by 0.46 eV in Ta�N¹ co-doped specimen due to the forming Ta�N bonding.Most strikingly,Ta�N co-doped TiO₂ have twofold photocatalytic ability better than pure TiO₂ under visible light excitation.?2?The crystal phase structure,chemical states,surface morphology and optical properties of Mn,N doped TiO₂ samples were characterize using Raman spectra,X-ray powder diffractometry,X-ray photoelectron spectroscopy,scanning electron microscopy and UV�vis absorption spectroscopy.Meanwhile,using first principles study the geometry structures,formation energies,electronic properties of all samples.Results show that the band gap value and the carrier mobility in the valence band and conduction band and the impurity levels have a synergetic can adjust the visible-light absorption and photocatalytic activity of the doped TiO₂.Especially,Mn-2N co-doped TiO₂ photocatalytic activity even better than three-fold pure TiO₂ under visible-light.?3?Bond formation and relaxation is an effective way to modulate the electronic properties and optical behavior of semiconductors.In this paper,with the aid of first principle calculations study the electronic properties of C,Fe,Co or H atom doped TiO₂.The results demonstrate that bonds formation and relaxation can change the electronic distribution around the impurity atoms.The optical behavior and electronic properties of TiO₂ are altered by adjusting the number of the impurity level,the energy of impurity level and the band gap.Further,the H atom being into TiO₂ crystal can increase the carrier mobility on the impurity levels.It not only can reduce the energies of the electronic transition,but also can suppress the photogenerated electron-hole recombination.Co-C-2H codoped TiO₂ may have the most excellent photocatalytic activity.