Steric Modification of a Cobalt Phthalocyanine/Graphene Catalyst To Give Enhanced and Stable Electrochemical CO₂ Reduction to CO

Abstract

Electrochemical conversion of CO2 into CO using metal complex/carbon-based heterogenized hybrids can be both highly efficient and selective. The ways in which the molecular complexes are immobilized on the carbon substrates and participate in the electrocatalytic reactions that yield CO2 reduction are not always well-understood. In this work, a highly soluble and sterically hindered cobalt(II) octaalkoxyphthalocyanine was successfully immobilized on chemically converted graphene via π–π stacking. In comparison to an analogous cobalt phthalocyanine/graphene catalyst, the alkoxy substitutions helped to suppress the phthalocyanine aggregation on the graphene sheets, resulting in a significantly enhanced catalytic activity by a single phthalocyanine molecule (∼5 s–1 at 480 mV overpotential) with stable CO conversion over 30 h of electrolysis.