Effect of Nickel Doping on Phase Transformation of TiO2 Nanotube Arrays

A simple way to introduce nickel doping into TiO 2 nanotube arrays by anodizing Ti-Ni alloy followed with thermal annealing is presented. The additional nickel has significant effect on the phase transformation behavior of TiO 2 nanotubes, which is of great significance in the construction of anatase-rutile heterojunction. GAXRD and DSC analysis results clearly demonstrate that the doping of nickel largely decreases the anatase-rutile phase transformation temperature of TiO 2 nanotubes from approximately 600–450 °C. XPS and TEM analyses reveal the nickel dopants mainly exist in the form of Ni 2+ , and successfully enter the titainia lattice by replacing Ti 4+ . The substitution doping of nickel and the subsequently increase of oxygen vacancies play important role in promoting the phase transformation from anatase to rutile.