Characterization and photocatalytic activity of nitrogen-doped titanium(IV) oxide prepared by doping titania with TiN powder

Abstract

Titanium(IV) oxide (TiO2) was doped with a small amount of TiN powder to obtain anatase nitrogen-doped TiO2(N-TiO2) with visible-light activity because the oxidation of TiN powder generally led to the formation of rutile N-doped TiO2. The synthesized N-TiO2 was yellow, and its UV–vis spectrum of N-TiO2 showed a continuous and tailing absorption in the visible region. The properties of N-TiO2 were compared with those of pureTiO2 and oxidized TiN particles. XRD patterns revealed that the ratio of the rutile phase to the anatase phase in N-TiO2 was lower than that in pure TiO2. These results indicate that the N atom dopants inhibit the phase transformation from anatase to rutile. The XRD patterns for all oxidized TiN particles showed the presence of the rutile phase. The results indicate that the TiO2 rutile phase is more likely to be formed by the heat treatment of TiN particles. The lack of phenol degradation in the presence of ST01 under visible light (423–600nm) irradiation indicated that the TiO2 anatase phase was inactive to visible light. On the other hand, a decrease in the phenol content for N-TiO2 calcined at 600°C (N-TiO2(600)), which was almost completely in the anatase form, revealed that N-doped anatase moieties responded favorably to visible light. The degradation amount for TiN particles oxidized at 600°C (TiN(600)) was comparable to that for N-TiO2(600) in spite of the fact that the nitrogen content of TiN(600) was larger than that of N-TiO2(600) (N/Ti=1.0 vs. N/Ti=0.10, respectively). The low degradation amount of TiN(600) was most likely due to the low fraction of the anatase phase and the presence of the cubic TiN phase. N-TiO2 prepared using a small addition of TiN particles showed visible-light activity originating from the anatase N-doped moieties.