Overturning CO₂ Hydrogenation Selectivity from CH₄ to CO by Strong Ru–FeO_<i>x</i> Interaction Arising from a Multilayer Epitaxial Structure

The catalytic conversion of CO₂ to CO through hydrogenation has emerged as a promising strategy for CO₂ utilization, given that CO serves as a valuable C1 platform compound for synthesizing liquid fuels and chemicals. However, the predominant formation of CH₄ via deep hydrogenation over Ru-based catalysts poses challenges in achieving selective CO production. High reaction temperatures often lead to catalyst deactivation and changes in selectivity due to dynamic metal evolution or agglomeration, even with a classic strong metal-support interaction. Herein, we have developed a FeO_<i>x</i>/Ru/Rutile multilayer epitaxial structure by depositing a FeO_<i>x</i> layer onto the epitaxially grown RuO₂ nanolayers on the surface of rutile nanoparticles. This multilayer epitaxial structure transformed into a structure in which Ru nanoparticles were decorated with FeO_<i>x</i> layers with ultrastable strong metal-support interaction (SMSI). Subsequently, the FeO_<i>x</i> decoration on Ru nanoparticles effectively shifted the dominant product from CH₄ to 95% CO during CO₂ hydrogenation. Remarkably, this catalyst exhibits exceptional stability and can be operated stably at 550 °C for a long time without apparent deactivation. Compared with the dynamic changes observed in supported Ru nanoparticles, the interaction between Ru and FeO_<i>x</i> maintains their electronic states at different reaction temperatures. Furthermore, this Ru-FeO_<i>x</i> interaction inhibits H₂ activation capability, CO adsorption, and subsequent hydrogenation of CO. The transformation strategy employed here, which utilizes initial multilayer epitaxial structures, can be applied to construct SMSI to enhance metal catalysts' catalytic performance.