On the Activity – or Lack Thereof – of RuO2 Based Electrodes in the Electrocatalytic Reduction of CO2

RuO2-based electrodes have been extensively studied for several electrochemical reactions. Earlier literature works claim RuO2-based catalysts to be active also for the electrocatalytic conversion of CO2 to methanol with high selectivity at very low overpotentials. Here we report a thorough investigation of RuO2 films and particles for the electrocatalytic reduction of CO2. The different experimental configurations explored in our work showed that H2 is basically the only reaction product under CO2 reduction conditions in contrast to earlier reports. In situ surface enhanced infrared absorption spectroscopy (SEIRAS) measurements revealed that CO bound to the RuO2 surface, albeit acting solely as spectator species. Our experiments indicated that adsorbed CO cannot be reduced further to methanol or other CO2 reduction products.