Controllable dispersion of cobalt phthalocyanine molecules on graphene oxide for enhanced electrocatalytic reduction of CO2 to CO

Abstract

Electrocatalytic reduction of CO₂ with non-precious materials containing the Co–N–C moiety as a catalyst is considered to be a promising method to achieve carbon neutrality. Unfortunately, metal phthalocyanines with an intrinsic Co–pyrrolic N₄–C structure usually show low electrocatalytic activity due to serious aggregation and low conductivity. Here, we exhibit a simple strategy to controllably disperse cobalt phthalocyanine (CoPc) on graphene oxide (GO) by the hydrolysis of protonated CoPc in GO aqueous phase. CoPc/GO nanocomposites with different ratios and structures could be easily obtained, and their effect on the electrocatalytic activity for the CO₂ reduction reaction (CO₂RR) to CO was systematically investigated. In the optimal sample, a CO selectivity of >96% can be achieved with an overpotential of <190 mV. Meanwhile, a CO Faradaic efficiency (FE_CO) of >90% can be reached within a wide potential range from −0.7 to −1.0 V (vs. RHE). The systematical experiments reveal that the synergy of CoPc and GO should be crucial owing to the existence of strong electrostatic interactions at the initial stage of hydrolysis and subsequent π–π, hydrogen bond and axial coordination interactions between CoPc and GO. This work exhibits a simple strategy to prepare molecule-based nanostructures as highly efficient electrocatalysts.