Novel Sb-doped ruthenium oxide electrode with ordered nanotube structure and its electrocatalytic activity toward chlorine evolution

An electrochemical method for the fabrication of nanostructured ruthenium oxide composite electrode from TiO2 nanotube arrays (TNTs) is presented. Briefly, activated TNTs support with improved electrical property was obtained by heat treatment, and ruthenium was subsequently deposited along the inner and outer surface of TiO2 nanotubes by electrochemical method. The as-prepared electrode showed a highly ordered nanotube structure with high specific surface area. Furthermore, the addition of Sb3+ into electrolyte could benefit the electrodeposition of ruthenium and the subsequent thermal oxidation process, which were proved by the more loaded RuO2 nanoparticles and the smaller particle size. Sb-doped RuO2/TNTs electrode prepared from the electrolyte containing a low concentration of Sb3+ showed a high electrocatalytic activity toward chlorine evolution, and the anodic current reached 170 mA cm−2 at 1.2 V. Excess Sb3+ in electrolyte, however, would lead to a remarkable decrease in electrode property as antimony is not an active ingredient for chlorine evolution reaction. A model Rs(Q1(R1(R2Q2))) was proposed to analyze the electrochemical impedance characteristic of the nanostructured electrodes. The charge transfer resistance on the Sb-doped RuO2/TNTs electrode was much smaller than that on a RuO2/TNTs electrode.

► A new method was developed to prepare ruthenium oxide electrode with ordered nanotube structure.
► The heat-treated TNTs enabled ruthenium growing along the inner and outer surface of nanotubes.
► Trace Sb3+ in electrolyte was beneficial to the electrodeposition of ruthenium and subsequent thermal oxidation.
► The Sb-doped RuO2/TNTs electrode showed high electrocatalytic activity toward chlorine evolution reaction.