Formation of Oxynitride as the Photocatalytic Enhancing Site in Nitrogen-Doped Titania Nanocatalysts: Comparison to a Commercial Nanopowder

A nitrogen‐doped TiO2 nanocolloid has been successfully prepared and its properties compared with the commercially available TiO2 nanomaterial, Degussa P25. Several characterization techniques, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), Fourier transform infrared (FT‐IR) spectroscopy, Raman scattering, and UV‐visible reflectance spectra, are combined in order to determine the crystal phase and grain size, shape, degree of nitrogen incorporation, and nature of the resultant oxynitride chemical bonding on the surface and in the bulk. The high relative photocatalytic activity of the nitrogen doped‐TiO2 nanocolloid is evaluated through a study of the decomposition of methylene blue under visible light excitation. The ease and degree of substitutional‐insertional nitrogen doping is held accountable for the significant increase in photocatalytic activity in the porous nanocolloid versus the nitrided commercial nanopowder. It is suggested that the nitrogen incorporation produces an NO bonding region as evidenced by the resulting XPS spectrum. A comparison between UV‐visible reflectance spectra for TiO2 nanocolloid particles Degussa P25 TiO2 nanopowder, and their nitrided analogs (see Figure) is described. The nitridation of the nanocolloid which can be accomplished in seconds at room temperature provides a visible light absorbing photocatalyst.