title: Marked enhancement of photocatalytic activity and photochemical stability of N-doped TiO2 nanocrystals by Fe3+/Fe2+ surface modification.
abstract: N-doped TiO(2) (N-TiO(2)) nanocrystals with anatase and rutile mixed phases were prepared by partial oxidation of TiN. The samples were further modified by Fe-ions through incipient wetness impregnation method. The as-prepared samples were characterized by XRD, TEM, XPS, Raman, EPR, UV-vis DRS, and PL in detail. The results indicated that Fe mainly existed as Fe(3+)/Fe(2+) ions on the catalyst surface. The addition of small amounts of Fe-ions to N-TiO(2) nanocrystals caused several times enhancement of the photocatalytic activity under visible, UV and UV-vis light irradiation in degradation of gaseous toluene. The optimized Fe-ions content in this investigation was 0.02 wt.%. EPR and PL clearly showed that Fe(3+)/Fe(2+) redox cycle facilitated electron/hole charge separation, and contributed to the enhanced photocatalytic performance. Moreover, the photochemical stability of N-TiO(2) nanocrystals under visible light was improved due to the stabilization of nitrogen atoms in TiO(2) lattice by surface Fe-ions modification. The N-doped TiO(2) nanocrystals without Fe-ions modification suffered from a gradual deactivation due mainly to the loss of lattice-nitrogen during the photocatalytic reaction. The way to modification of nonmetal-doped TiO(2) nanomaterials brought new concept in enhancing the photocatalytic performance from the viewpoint of practical application.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310027, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Dong
authors.forename: Haiqiang
authors.initials: H
authors.lastname: Wang
authors.forename: Zhongbiao
authors.initials: Z
authors.lastname: Wu
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Qiu