Synthesis and characterization of N-doped TiO2/ZrO2 visible light photocatalysts

Zirconia and nitrogen-doped TiO2 powder was synthesized using a polymer complex solution method for the preparation of an enhanced visible light photocatalyst. The produced catalysts were characterized via the Brunauer, Emmett, and Teller method (BET), X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, and UV–Vis spectrophotometry analyses. The N-doped TiO2/ZrO2 photocatalyst showed a high specific surface area and small crystal sizes. The XPS spectra of the N-doped TiO2/ZrO2 sample indicated that nitrogen was doped into the TiO2 lattice and enhanced the photocatalytic activity. The UV–Vis absorption spectra of the N-doped TiO2/ZrO2 sample noticeably shifted to the visible light region compared to that of the TiO2. The photocatalytic activities of the prepared catalysts were evaluated for the decomposition of gaseous NOx under UV and visible light irradiations. The photocatalytic activities of N-doped TiO2/ZrO2 were much greater than those of commercial Degussa P25 in both the UV and visible light regions. The high photocatalytic activity can be attributed to stronger absorption in the visible light region, a greater specific surface area, smaller crystal sizes, more surface OH groups, and to the effect of N-doping, which resulted in a lower band gap energy.