Mo₂C Morphology Dependence in Co–Mo₂C Interface Structure Evaluation for Boosting α-Olefin Hydroformylation

The hydroformylation of high-carbon α-olefins is a pivotal industrial process. Still, heterogeneous Co-based catalysts suffer from low activity and Co leaching due to strong coordination of CO to Co atoms. Herein, we address the dynamic evolution and active structure of Co species by interacting Co nanoparticles or ultrahigh-dispersed clusters with β-Mo₂C nanoparticles (Co-30Mo₂C_particle/CNF) and nanofilms (Co-100Mo₂C_film/CNF) on carbon nanofibers. The specific activity in the formation of heptanal from 1-hexene hydroformylation increased by 10.7 times on Co-30Mo₂C_particle/CNF (21.4 mol_heptanal/mol_Co/h) and 2.4 times on Co-100Mo₂C_film/CNF (4.7 mol_heptanal/mol_Co/h) compared with Co/CNF (2.0 mol_heptanal/mol_Co/h). Moreover, Co-100Mo₂C_film/CNF exhibits enhanced stability with only 1.7% Co leaching. The Mo₂C nanoparticles interact with Co nanoparticles, oxidizing them to form highly active Co-MoO_x sites with a lower CO insertion barrier. The reaction environment influences the structural evolution of the Co-MoO_x interaction. In contrast, Mo₂C nanofilms form robust Co–C and Co–Mo bonds at the Co–Mo₂C interface, stabilizing atomically distributed Co clusters against leaching. This work establishes a morphology-driven strategy to control the dynamic interaction of Co and additives, thereby decoupling activity and stability in heterogeneous catalysis for hydroformylation.