Operando X-ray characterization platform to unravel catalyst degradation under accelerated stress testing in CO2 electrolysis

Abstract

Membrane-electrode assembly (MEA)-based CO₂ electrolysis shows great potential for industrial-scale chemical production, but long-term stability remains a key challenge. The degradation mechanisms of catalysts and electrodes in MEAs are not yet fully understood. Here a customized operando synchrotron X-ray characterization platform was established to track the time- and space-resolved evolution of ions and water movement, crystal structure and catalyst variations in MEAs. Using Au and Ag model catalysts, we show that the crystalline phase catalyst stability and catalyst–substrate adhesion are critical to MEA durability. Small- and wide-angle X-ray scattering analysis reveals that Au catalysts, with their robust crystal structure and stable catalyst–substrate adhesion, maintain stability under accelerated stress tests, whereas Ag catalysts degrade due to particle agglomeration, an undesirable dissolution–recrystallization process and detachment. This study demonstrates the advanced capabilities of operando X-ray techniques in elucidating catalyst and electrode degradation in CO₂ electrolysers.