Direct cleavage of C=O double bond in CO₂ by the subnano MoO_x surface on Mo₂N

Compared to H₂-assisted activation mode, the direct dissociation of CO₂ into carbonyl (*CO) with a simplified reaction route is advantageous for CO₂-related synthetic processes and catalyst upgrading, while the stable C = O double bond makes it very challenging. Herein, we construct a subnano MoO₃ layer on the surface of Mo₂N, which provides a dynamically changing surface of MoO₃↔MoO_x (x < 3) for catalyzing CO₂ hydrogenation. Rich oxygen vacancies on the subnano MoO_x surface with a high electron donating capacity served as a scissor to directly shear the C = O double bond of CO₂ to form CO at a high rate. The O atoms leached in CO₂ dissociation are removed timely by H₂ to regenerate active oxygen vacancies. Owing to the greatly enhanced dissociative activation of CO₂, this MoO_x/Mo₂N catalyst without any supported active metals shows excellent performance for catalyzing CO₂ hydrogenation to CO. The construction of highly disordered defective surface on heterostructures paves a new pathway for molecule activation.