Photo‐Assisted Electrochemical CO2 Reduction to CH4 Using a Co‐Porphyrin‐Based Metal–Organic Framework

Abstract

Metal–organic frameworks (MOFs) are a promising platform for assembling large concentrations of molecular catalysts on surfaces to drive the electroreduction of CO2. Yet until now, these MOF‐based systems were shown to produce only 2‐electron/proton products, i.e., CO or formic acid. Herein, it is demonstrated that a cobalt 5,10,15,20‐tetra(4‐carboxyphenyl) porphyrin (CoTCPP)‐based MOF can produce significant quantities of an 8‐electron/proton CH4, via a photo‐assisted electrocatalytic approach. Specifically, detailed electrochemical and spectro‐electrochemical analyses show that the addition of light illumination during electrocatalysis promotes the stabilization of a catalyst‐bound CO intermediate, allowing its further reduction to the final product, CH4. Using the photo‐assisted electrocatalysis method, maximum CH4 Faradaic efficiency of 14% was obtained at a low potential of −0.49 V NHE. Hence, the presented concept provides an additional step toward the design of more efficient MOF‐based electrocatalytic systems.