Electrochemical Photocatalytic Degradation of Orange G Using TiO2 Films Prepared by Cathodic Deposition

Abstract

Herein, we report that organic dyes with poor adsorption on photocatalysts (e. g., OG (orange G) on TiO2) can only be significantly degraded via the indirect oxidation process by the electrochemical photocatalytic (EPC) or photo-electro-Fenton (PEF) mechanisms because of their enhanced electron-hole separation for generating H2O2. The TiO2/Ti photo-anodes were prepared by cathodic deposition from a bath containing TiCl3, HCl, H2O2, and NaNO3 under a two-electrode mode for EPC dye degradation. Effects of the deposition cell voltage, deposition time, and annealing temperature on the photocatalytic activity of TiO2 films, evaluated by the photocurrent density, are systematically investigated. The surface morphologies and crystalline structure of various TiO2 films were studied using scanning electron microscopic (SEM) and X-ray diffraction (XRD) analyses. The EPC characteristics of TiO2/Ti photo-anodes combined with a graphite cathode toward the OG degradation have also been evaluated. The maximal photocatalytic activity is obtained for the TiO2/Ti photo-anode deposited at a cell voltage of 2.6 V for 20 min and annealed at 700 degrees C in air for 1 hr, which exhibits a photocurrent density of 22.86 mu Amg(-1). The order of degradation modes with respect to decreasing the degradation efficiency of OG is: PEF > EPC > PC (photocatalytic) > EC (electrocatalytic) oxidation. (C) 2014 The Electrochemical Society. All rights reserved.