Facet-Dependent Solid Frustrated Lewis Pairs on Co₃O₄ Catalysts Towards Semi-Hydrogenation Reaction of Alkynols

The semi-hydrogenation of alkynols to enols represents a vital industrial reaction for fine chemical synthesis, yet developing highly selective non-noble metal catalysts remains an urgent challenge. Herein, we report a Co₃O₄ nanorod (Co₃O₄-NR) catalyst with abundant solid-frustrated Lewis pairs (SFLPs) on specifically exposed {110} facets, where coordinatively unsaturated Co²⁺ acts as Lewis acid site whilst the surface hydroxyl group serves as Lewis base site. The Co₃O₄-NR catalyst exhibits exceptional performance toward semi-hydrogenation from 3-butyn-1-ol to 3-buten-1-ol with a product yield of 88.2%, which is preponderate to other non-noble metal catalysts. Poisoning experiments, in situ DRIFTS and theoretical calculations verify that the SFLPs sites serve as intrinsic active centers for H₂ activation/dissociation and substrate adsorption. The hydrogenation of key intermediate (C₄H₇O*) is identified as the rate-determining step, where H^δ+ species strongly tethered to surface -OH group suppresses over-hydrogenation and thereby enhances the semi-hydrogenation selectivity. Projected density of states (PDOS) analysis reveals an accelerated hydrogenation kinetics via d-p orbital hybridization between Co 3d orbitals and C 2p orbitals in C₄H₇O*. This work advances the design of efficient and cost-effective SFLPs-based heterogeneous catalysts, which shows potential application in the synthesis of fine chemicals.