Cu Nanoparticle Infiltration via Metal–Organic Decomposition Ink for Superior Mass Activity in CO Electroreduction

Achieving stable operation at high currents remains challenging for gas diffusion electrode (GDE)-based CO electrolyzers. Herein, we demonstrate the importance of Cu nanoparticle infiltration into the microporous layer to enrich local CO accessibility and mitigate electrolyte crossover. A facile GDE preparation method is developed via the doctor-blading method using a Cu metal–organic decomposition (Cu MOD) ink to produce well-dispersed nanoparticles across the porous layer. This design produces highly selective C2+ products at –1200 mA cm–2 from the CO electroreduction reaction, achieving a remarkably high mass activity of approximately –28,000 A g–1. It is found that the Cu electrodes prepared by MOD improve a stable balanced gas–liquid–solid interface by CO transport across the hydrophobic microenvironment of the inherent microporous layer. Our insights offer perspectives on a scalable strategy for optimizing catalyst positioning and advancing stable GDEs with high mass activity.