Electrochemically substituted metal phthalocyanines, e-MPc (M = Co, Ni), as highly active and selective catalysts for CO2 reduction

Abstract

Metal-oxide nanoclusters (NCs) such as FeO_x, CoO_x, and NiO_x are incorporated into iron phthalocyanine (FePc) supported on graphene, MO_x/FePc, via a facile self-assembly method. MO_x/FePc electrocatalysts show high activity, selectivity and stability for the electrochemical CO₂ reduction reaction (CO₂RR) as compared with the corresponding metal phthalocyanines, i.e., FePc, CoPc and NiPc, under identical test conditions. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy reveals that MO_x/FePc undergoes a metal ion replacement of the iron center of Pc, forming electrochemically substituted metal Pc, e-MPc where M = Co and Ni, co-existing with the replaced FeO_x nanoparticles (NPs) in the vicinity of the e-MPc. The results indicate that the e-MPc with in situ dispersed FeO_x NPs, FeO_x/e-CoPc and FeO_x/e-NiPc exhibits excellent activity, high selectivity and stability for the CO₂RR.