In Situ Electropolymerizing Toward EP‐CoP/Cu Tandem Catalyst for Enhanced Electrochemical CO2‐to‐Ethylene Conversion

Abstract Electrochemical CO 2 reduction has garnered significant interest in the conversion of sustainable energy to valuable fuels and chemicals. Cu‐based bimetallic catalysts play a crucial role in enhancing * CO concentration on Cu sites for efficient C─C coupling reactions, particularly for C 2 product generation. To enhance Cu's electronic structure and direct its selectivity toward C 2 products, a novel strategy is proposed involving the in situ electropolymerization of a nano‐thickness cobalt porphyrin polymeric network (EP‐CoP) onto a copper electrode, resulting in the creation of a highly effective EP‐CoP/Cu tandem catalyst. The even distribution of EP‐CoP facilitates the initial reduction of CO 2 to * CO intermediates, which then transition to Cu sites for efficient C─C coupling. DFT calculations confirm that the * CO enrichment from Co sites boosts * CO coverage on Cu sites, promoting C─C coupling for C 2+ product formation. The EP‐CoP/Cu gas diffusion electrode achieves an impressive current density of 726 mA cm −2 at −0.9 V versus reversible hydrogen electrode (RHE), with a 76.8% Faraday efficiency for total C 2+ conversion and 43% for ethylene, demonstrating exceptional long‐term stability in flow cells. These findings mark a significant step forward in developing a tandem catalyst system for the effective electrochemical production of ethylene.