Effect of Acid Etchants on Surface Morphology and Electrochemical Properties of Titanium Substrates and Their IrO2-PbO2 Coatings
The Ti/IrO2-PbO2 anodes were prepared by thermal decomposition.The effects of sulfuric acid,nitric acid,hydrochloric acid,oxalic acid and hydrochloric acid/oxalic acid etching sequence on the performance of Ti/IrO2-PbO2 anodes were studied.Surface morphologies,structure and electrochemical behavior of the titanium substrates with oxide-coating were investigated by field emission scanning electron microscope,X-ray diffraction,cyclic voltammetry,linear scanning voltammetry,electrochemical AC impedance spectroscopy and accelerated lifetime test.The results show that dual-acid etching can obtain better corrosion effect and denser and more uniform surface structure compared to single-acid etching.The dual-acid etching achieves a complete TiHx crystal form which is beneficial to increase the coating loading and to enhance the bonding force between the active layer and the substrate.The electrochemical properties of the anode are slightly determined by the order of double acid etching.The Ti/IrO2-PbO2 anode treated by oxalic acid/hydrochloric acid shows the best electrocatalytic activity and the longest accelerated lifetime.