Rational Designing Microenvironment of Gas‐Diffusion Electrodes via Microgel‐Augmented CO 2 Availability for High‐Rate and Selective CO 2 Electroreduction to Ethylene

Abstract Efficient electrochemical CO 2 reduction reaction (CO 2 RR) requires advanced gas‐diffusion electrodes (GDEs) with tunned microenvironment to overcome low CO 2 availability in the vicinity of catalyst layer. Herein, for the first time, pyridine‐containing microgels‐augmented CO 2 availability is presented in Cu 2 O‐based GDE for high‐rate CO 2 reduction to ethylene, owing to the presence of CO 2 ‐phil microgels with amine moieties. Microgels as three‐dimensional polymer networks act as CO 2 micro‐reservoirs to engineer the GDE microenvironment and boost local CO 2 availability. The superior ethylene production performance of the GDE modified by 4‐vinyl pyridine microgels, as compared with the GDE with diethylaminoethyl methacrylate microgels, indicates the bifunctional effect of pyridine‐based microgels to enhance CO 2 availability, and electrocatalytic CO 2 reduction. While the Faradaic efficiency (FE) of ethylene without microgels was capped at 43% at 300 mA cm −2 , GDE with the pyridine microgels showed 56% FE of ethylene at 700 mA cm −2 . A similar trend was observed in zero‐gap design, and GDEs showed 58% FE of ethylene at −4.0 cell voltage (>350 mA cm −2 current density), resulting in over 2‐fold improvement in ethylene production. This study showcases the use of CO 2 ‐phil microgels for a higher rate of CO 2 RR‐to‐C 2+ , opening an avenue for several other microgels for more selective and efficient CO 2 electrolysis.