Crystal Phase Engineering of Cobalt‐Based Catalyst for Switching CO ₂ Hydrogenation Selectivity From CH ₄ to CO

ABSTRACT Altering the inherent selectivity of catalysts toward the C 1 product is of great significance for enriching the selection of CO 2 directional conversion. Herein, we demonstrate that regulating the crystal phase of cobalt (Co)‐based catalysts enables a dramatic shift from methane (CH 4 ) to carbon monoxide (CO). At 320°C and ambient pressure, the Co with a face‐centered cubic structure (FCC‐Co) predominantly yields CH 4 in CO 2 hydrogenation, achieving 94% of CH 4 selectivity and 53% of CO 2 conversion, while the hexagonal close‐packed structure (HCP‐Co) exhibits exceptional selectivity toward CO, with 96% of CO selectivity and 21% of CO 2 conversion. Multimodal characterizations reveal that compared to FCC‐Co, the lower content of oxygen vacancies and metallic Co 0 over HCP‐Co results in the weak CO 2 /CO adsorption and insufficient hydrogen dissociation, which suppresses the CO→CH 4 step in the CO 2 hydrogenation, thereby redirecting product selectivity toward CO rather than CH 4 . This work highlights crystal phase tailoring of Co‐based catalysts as a viable strategy to regulate product selectivity in CO 2 hydrogenation, offering insights for rational catalyst design in RWGS reactions.