Characterization and activity of visible-light-driven TiO2 photocatalyst codoped with nitrogen and cerium

Nitrogen and cerium codoped TiO2 photocatalysts were prepared by a modified sol–gel process with doping precursors of cerium nitrate and urea, and characterized by X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry (TG–DSC), X-ray photoelectron spectra (XPS) and ultraviolet–visible light diffuse reflectance spectra (UV–vis DRS). Results indicate that anatase TiO2 is the dominant crystalline type in as-prepared samples, and CeO2 crystallites appear as the doping ratio of Ce/Ti reaches to 3.0 at%. The TiO2 starts to transform from amorphous phase to anatase at 987.1 K during calcination, according to the TG–DSC curves. The XPS show that three major metal ions of Ce3+, Ce4+, Ti4+ and one minor metal ion of Ti3+ coexist on the surface. The codoped TiO2 exhibits significant absorption within the range of 400–500 nm compared to the non-doped and only nitrogen-doped TiO2. The enhanced photocatalytic activity of the codoped TiO2 is demonstrated through degradation of methyl orange under visible light irradiation.

Graphical abstractA novel TiO2 photocatalyst codoped with nitrogen and cerium was synthesized and characterized. An enhanced visible light activity was achieved. UV–vis DRS results indicated that the optical absorption edge of the N–Ce codoped TiO2 was obviously shifted to the visible light range as the Ce/Ti doping ratio increased.Figure optionsDownload full-size imageDownload as PowerPoint slide