Vertically Oriented TiOxNy Nanopillar Arrays with Embedded Ag Nanoparticles for Visible-Light Photocatalysis

We present a straightforward method to produce highly crystalline, vertically oriented TiOxNy nano-pillars (up to 1 mu m in length) with a band gap in the visible-light region. This process starts with reactive dc sputtering to produce a TiN porous film, followed by a simple oxidation process at elevated temperatures in oxygen or air. By controlling the oxidation conditions, the band gap of the prepared TiOxNy can be tuned to different wavelength within the range of visible light. Furthermore, in order to inhibit carrier recombination to enhance the photocatalytic activity, Ag nanoparticles have been embedded into the nanogaps between the TiOxNy pillars by photoinduced reduction of Ag+ (aq) irradiated with visible light. Transmission electron microscopy reveals that the Ag nanoparticles with a diameter of about 10 nm are uniformly dispersed along the pillars. The prepared TiOxNy nanopillar matrix and Ag:TiOxNy network show strong photocatalytic activity under visible-fight irradiation, evaluated via degradation of Rhodamine B.