Engineering catalyst-support interactions in cobalt phthalocyanine for enhanced electrocatalytic CO reduction: the role of graphene-skinned AlO.

Electrocatalytic CO reduction (eCOR) driven by renewable electricity holds great promise to mitigate anthropogenic CO emissions. In this study, we engineer cobalt phthalocyanine (CoPc) supported on graphene-skinned AlO nanosheets (CoPc/AlO@C) to enhance CO-to-CO conversion. The strong π-π stacking between the CoPc macrocycle and interlayer graphene, coupled with electronic repulsion between the Co center and AlO, induces a structural distortion in CoPc, raising the energy level of the d orbital. This structural perturbation facilitates CO activation, shifts the rate-determining step, and thereby substantially accelerates the overall eCOR kinetics. The optimal catalyst demonstrates a near-unity CO faradaic efficiency (FE) across a wide current range, achieving a high CO partial current density of 388 mA cm with an exceptional turnover frequency (TOF) of 43 s, in addition to prolonged operational stability in a membrane electrode assembly (MEA). This work, by leveraging the vectorial interactions between molecular moieties and the substrate to reshape the macrocyclic structure and realign the orbital energies of CoPc, offers new insights into the design of efficient electrocatalysts for eCOR.