Engineering catalyst–support interactions in cobalt phthalocyanine for enhanced electrocatalytic CO2 reduction: the role of graphene-skinned Al2O3

Abstract

Electrocatalytic CO₂ reduction (eCO₂R) driven by renewable electricity holds great promise to mitigate anthropogenic CO₂ emissions. In this study, we engineer cobalt phthalocyanine (CoPc) supported on graphene-skinned Al₂O₃ nanosheets (CoPc/Al₂O₃@C) to enhance CO₂-to-CO conversion. The strong π–π stacking between the CoPc macrocycle and interlayer graphene, coupled with electronic repulsion between the Co²⁺ center and Al₂O₃, induces a structural distortion in CoPc, raising the energy level of the d_z² orbital. This structural perturbation facilitates CO₂ activation, shifts the rate-determining step, and thereby substantially accelerates the overall eCO₂R kinetics. The optimal catalyst demonstrates a near-unity CO faradaic efficiency (FE_CO) across a wide current range, achieving a high CO partial current density of 388 mA cm⁻² with an exceptional turnover frequency (TOF) of 43 s⁻¹, 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 eCO₂R.