The Role of TiO₂Doping on RuO₂-Coated Electrodes for the Water Oxidation Reaction

Abstract

Electrochemical water splitting into H 2 and O 2 presents a significant and challenging energy loss due to the high overpotential required at the anode. Today, in industrially relevant applications, dimensionally stable anodes (DSA) based on the electrocatalytic active RuO 2 are conventionally utilized. To enhance the resistance against corrosion, incorporation of TiO 2 in the RuO 2 -coated electrodes is widely employed. In the present work we have used scanning electrochemical microscopy (SECM) to demonstrate that TiO 2 -doped RuO 2 -coated electrodes, in addition to being more durable, also show an electrocatalytic activity that is, on average, 13% higher as compared to the pure RuO 2 -coated electrodes. We also demonstrate that cracks in the pure RuO 2 coating are the most active zones, probably because Ti from the Ti support has diffused into the first applied layer of the RuO 2 coating. To reveal the nature of this enhanced activity for water oxidation displayed on TiO 2 -doped RuO 2 electrodes, we have employed X-ray photoelectron spectroscopy (XPS) for material characterization. The results show that the electrocatalytic activity enhancement displayed on the mixed (Ru 1– x:Ti x )O 2 coating is promoted through a charge transfer from the RuO 2 to the TiO 2, which provides new and more reactive sites designated as activated RuO 2 δ+ .