The Study On Preparation And Photoelectric Performances Of Cu/Au And N Co-doped TiO₂ Nanotubes

As one of the most important functional semiconductor materials,titanium dioxide?TiO₂?is widely used in solar cells,photocatalytic degradation of pollutants,sensors,biomedicine and other fields due to its non-toxic,cheap,and good photoelectric properties.Because of the unique ordered tubular structure,large specific surface area and controllable size,TiO₂ nanotubes have received more and more attention in recent years.However,large optical-band gap?3.2eV for anatase and 3.0 eV for rutile?and fast recombination of the photo-generated electron-hole pairs are the two inherent disadvantages of TiO₂,which have limited its applications in many ways.Doping is an effective way to solve these two shortcomings and brings new hope to its practical application.The traditional doping methods have the problems such as low doping amount,uneven doping,and easily cause secondary pollution.In this paper,metal doped and metal-non-metal co-doped TiO₂ nanotube were prepared by magnetron sputtering and anodization method.The doped elements by this method not only evenly distributed in the nanotubes but also its amount can be easily controlled.Furthermore,this method eliminating the problem of secondary pollution and the photoelectric properties of the doped nanotubes have also been significantly improved.?1?Cu-doped TiO₂?Cu-TiO₂?nanotubes were prepared by magnetron sputtering and anodic oxidation method.Scanning electron microscopy?SEM?,X-ray diffraction?XRD?,transmission electron microscopy?TEM?and X-ray photoelectron spectroscopy?XPS?analysis indicated that the position of Ti ion in the lattices of TiO₂ nanotubes was replaced by the Cu ion.The addition of Cu ions affected the growth orientation of the nanotubes,and the recombination of photoelectron-hole pairs were effectively suppressed.With the increase of Cu doping,the nanotubes structure were broken and collapsed,and ordered tubular structure were destroyed.?2??Cu,N?co-doped TiO₂ nanotubes were prepared by the same method except that nitrogen gas was introduced during the magnetron sputtering.The results show that the introduction of N element promoted the phase transition from anatase to rutile.O element was replaced by N and N was substitutional doping but the doping methods of Cu element have not been affected by the addition of N element.?Cu,N?co-doped TiO₂ nanotubes not only could reduce the band gap of TiO₂,but also could effectively inhibit the recombination of photoelectron-hole pairs.Compared with single Cu doped TiO₂ nanotubes,?Cu,N?co-doped nanotubes shown better photoelectric properties.?3?Cu was replaced by noble metal-Au,which is in the same subgroup of Cu in the periodic table of elements.The?Au,N?co-doped TiO₂ nanotubes were prepared by the same method.The results show that Au nanoparticles,not Au ions existed in the nanotubes and the Au nanoparticles were easily agglomerated in the nanotubes,which was very different from Cu.The growth of the nanotubes were inhibited by the addition of Au and with the increase of Au amount,two layer of TiO₂ appeared and separated by the agglomerated Au nanoparticles.The photocurrent value of?Cu,N?co-doped TiO₂ nanotubes was lower than that of?Au,N?co-doped TiO₂ nanotubes.