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

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