Exclusive Co-N4 Sites Confined in Two-dimensional Metal-Organic Layers Enabling Highly Selective CO2 Electroreduction at Industrial-Level Current

Abstract

Metal-organic framework catalysts bring new opportunities for CO₂ electrocatalysis. Herein, we first conduct density-functional theory calculations and predict that Co-based porphyrin porous organic layers (Co-PPOLs) exhibit good activity for CO₂ conversion because of the low *CO adsorption energy at Co-N₄ sites, which facilitates *CO desorption and CO formation. Then, we prepare two-dimensional Co-PPOLs with exclusive Co-N₄ sites through a facile surfactant-assisted bottom-up method. The ultrathin feature ensures the exposure of catalytic centers. Together with large specific area, high electrical conductivity and CO₂ adsorption capability, Co-PPOLs achieve a peak faradaic efficiency for CO production (FE_CO =94.2 %) at a moderate potential in CO₂ electroreduction, accompanied with good stability. Moreover, Co-PPOLs reach an industrial-level current above 200 mA in a membrane electrode assembly reactor, and maintain near-unity CO selectivity (FE_CO >90 %) over 20 h in CO₂ electrolysis.

Keywords: Bottom-up Method; CO2 Reduction; Co-N4 Sites; MEA Device; Porphyrin Porous Organic Layers.