Atomic Arrangement of AuAg Alloy on Carbon Support Enhances Electrochemical CO2 Reduction in Membrane Electrode Assembly

Abstract

Tailoring catalyst performance is especially crucialin a zero-gapmembrane-electrode assembly (MEA) electrolyzers for electrochemicalCO(2) reduction reaction at the industrial scale. However,few studies have directly focused on MEA systems combined with operando techniques when compared to aqueous catholyte-basedflow cells or H-cells. Using the MEA system, this study demonstratesimproved catalytic performance of the AuAg bimetallic catalyst byadjusting the atomic arrangement of the alloy structure and its extrinsicproperties with a carbon support. The AuAg catalyst containing only10 at. % Au and the AgCl domain underwent atomic arrangement via AgClreduction. The catalyst with more oxidative Ag species achieved near-unityCO selectivity (97.3%) and three-fold higher CO partial current comparedto Ag nanoparticles. Operando X-ray absorption analysisof the active AuAg catalyst in the MEA cell demonstrates that theAuAg active site contained more Ag+ and under-coordinatedsurfaces. When the carbon support was properly adjusted, high CO productionactivity is achieved with a CO partial current density and mass activityof 618 mA cm(-2) and 0.824 A mg(-1), respectively, by effectively alleviating the mass transport restriction.AuAg catalysts are competitive with CO2-to-CO catalystsin MEA because their intrinsic and extrinsic properties can be properlycontrolled.