Figure 2 shows the photocatalytic activities of Degussa P-25 nd undoped and doped TiO2 with different nitrogen source n the optimal mole ratio of N to Ti. Compared to that of the undoped TiO2, the phtotocatalytic activities of nitrogen-doped
TiO2 with organic nitrogen sources are improved greatly and much higher than that of Degussa P-25. Especially the nitrogen-doped TiO2 using triethylamine as the nitrogen source shows the highest photocatalytic decomposition efficiency. Thereafter, taking the nitrogen-doped TiO2 with triethylamine (denoted as N TiO2) as an example, we further investigate the crystal phase, characters, and chemical states of the doped nitrogen and illustrate the probable reasons for the improvement in decomposition of rhodamine B and 2,4-dichlorophenol.