Electrochemical study of the metal-support interaction between FeOx nanoparticles and cobalt oxide support for the reverse water gas shift reaction

Abstract

CO2 transformed into CO is the initial step in the manufacturing of carbon-neutral products. Herein, the supported iron-oxide (FeOx) nanoparticles are investigated for the reverse water gas shift (RWGS) reaction from 200 °C to 400 °C under atmospheric conditions. The effect of the catalyst support is investigated by comparing unsupported and supported FeOx on Co3O4 and γ-Al2O3 supports. The FeOx/Co3O4 catalytic system displayed a high selectivity to CO (>99 %), a 1.4-fold CO2 conversion increase over bare Co3O4 support and a 20-times improvement over FeOx/γ-Al2O3. The superior catalytic activity of FeOx/Co3O4 is attributed to the reducibility of Co3O4 under the reaction conditions and generation of oxygen vacancies. This in turn affected the electronic properties of the FeOx catalyst and as a result improved its catalytic activity for the RWGS reaction. To confirm the effect of oxygen vacancies in Co3O4 and the observed metal-support interaction (MSI), we performed electrochemical characterizations of the FeOx/Co3O4 catalyst. Under both anodic and cathodic polarization, the catalytic activity decreased by over 10 % due to the in-situ change in the oxidation state of Co3O4 during polarization, thus affecting the MSI effect between FeOx and Co3O4. Our study demonstrates that the application of electrochemical methods for studying the MSI effect in heterogeneous catalysts is a powerful and informative in-situ tool.