Enhanced photocatalytic activity of Cu-deposited N-TiO2/titanate nanotubes under UV and visible light irradiations

A rapid and green synthesis of Cu-deposited N-doped TiO2/titanate nanotubes (TNTs) by the aid of microwave-assisted hydrothermal method was developed for the enhanced photocatalytic activity toward bisphenol A (BPA) degradation under UV and visible light irradiations. The TNTs are first synthesized at 150 degrees C for 3 h by microwave-assisted method followed by the calcination at 450 degrees C under NH3/N-2 atmosphere after the adsorption of 2-10 wt% Cu(II) ions to produce metallic Cu-deposited N-TiO2/TNTs nanocomposites. The microstructural analyses show that the Cu(II) ions are converted to Cu-0 in NH3/ N-2 with mean particle sizes of 39-42 nm and N atoms are incorporated into the lattices of TiO2/TNTs. The Cu-deposited N-TiO2/TNT nanocomposites show the superior photoactivity toward BPA degradation under both UV and visible light irradiations. The photodegradation efficiency and rate of BPA increases upon increasing Cu amount and the optimal mass loadings of 8-10 wt% are obtained. In addition, the pseudo-first-order rate constants for BPA degradation increase 5.3-6.8 and 2.1-3.0 times under UV and visible light irradiations, respectively, when compare with those of Degussa P25 TiO2. The Schottky barrier between Cu-0 and N-TiO2 promotes the electron transfer from N-doped TiO2 to metallic Cu nanoparticles under UV and visible light irradiations, resulting in the efficient generation of prolonged oxygen-containing radicals for enhanced photodegradation of BPA. Results obtained in this study clearly open a new pave for the green synthesis of 1-dimensional metal-metal oxide nanophotocatalysts which can be potentially used in the fields of purification, green chemistry and photocatalysis. (C) 2017 Elsevier B.V. All rights reserved.