Structure of Nitrogen and Zirconium Co-Doped Titania with Enhanced Visible-Light Photocatalytic Activity

Abstract

Nitrogen and zirconium co-doped TiO₂ (TiO₂–N–<i>x</i>%Zr) photocatalysts were synthesized via a sol–gel method. The existing states of the dopants (N and Zr) and their corresponding band structures were investigated via XRD, Raman, BET, XPS, TEM, FT-IR, UV–vis DRS, and PL techniques. It was found that N existed only as a surface species (NO_<i>x</i>) and Zr⁴⁺ was doped in a substitutional mode; the doping of Zr⁴⁺ ions and modification of N extended the absorption into the visible region and inhibited the recombination of electrons and holes. Moreover, the excess Zr⁴⁺ ions existed as the ZrTiO₄ phase when the content of Zr was sufficiently high, which could also contribute to the separation of the charge carriers. Therefore, the TiO₂–N–<i>x</i>%Zr samples show enhanced visible-light photocatalytic activity compared with single-doped TiO₂. These results offer a paradigm for the design and fabrication of optoelectronic functional materials such as solar cells and photocatalysts