Oxide-Oxide Interactions Dominating the Reaction Pathways in CO₂-Assisted Oxidative Dehydrogenation of Ethane

The CO₂-assisted oxidative dehydrogenation of ethane (CO₂-ODHE) has attracted increasing attention due to the dual benefits of ethylene production and CO₂ utilization. Among the CO₂-ODHE catalysts, low-cost Co-based catalysts have received special interest recently. However, the complex chemical states of cobalt species lead to competing pathways in CO₂-ODHE, casting a shadow on their application potential. Herein, we designed two identical-composition Co₃O₄-ZrO₂ catalysts with different interfaces and found that the inverse-structured Co₃O₄@ZrO₂-IE synthesized via ion exchange achieved 83% ethylene selectivity; conversely, the traditional supported Co₃O₄/ZrO₂-WI prepared by impregnation resulted in primarily CO formation. Comprehensive investigations based on in situ characterizations and theoretical calculations revealed that during the CO₂-ODHE process, the weaker interfacial oxide-oxide interactions in Co₃O₄/ZrO₂-WI made Co₃O₄ readily reduced to metallic Co⁰, deeply scissoring C─H and C─C bonds, then reacting with O* derived from CO₂ dissociation, promoting the formation of C₂H₅O* and CH_x* key intermediates leading to ethane dry reforming. Contrastingly, the enhanced oxide-oxide interactions in Co₃O₄@ZrO₂-IE inhibited excessive reduction of Co₃O₄, forming stable interface-confined Zr-O_v-Co²⁺ sites, favored C─H bond activation for the formation of C₂H₅*, while inhibiting C₂H₅O* and CH_x*, thereby resulting in dehydrogenation to ethylene. This work highlights modulating oxide-oxide interactions as a new strategy for fabricating advanced catalysts.