Supramolecular Porphyrin Cages Assembled at Molecular-Materials Interfaces for Electrocatalytic CO Reduction

Conversion of carbon monoxide (CO), a major one-carbon product of carbon dioxide (CO2) reduction, into value-added multicarbon species is a challenge to addressing global energy demands and climate change. Here we report a modular synthetic approach for aqueous electrochemical CO reduction to carbon-carbon coupled products via self-assembly of supramolecular cages at molecular-materials interfaces. Heterobimetallic cavities formed by face-to-face coordination of thiolterminated metalloporphyrins to copper electrodes through varying organic struts convert CO to C-2 products with high faradaic efficiency (FE = 83% total with 57% to ethanol) and current density (1.34 mA/cm(2)) at a potential of -0.40 V vs RHE. The cagefunctionalized electrodes offer an order of magnitude improvement in both selectivity and activity for electrocatalytic carbon fixation compared to parent copper surfaces or copper functionalized with porphyrins in an edge-on orientation.