Coupling oxidation state and catalyst stability during pulsed electrochemical CO2 reduction via operando X-ray absorption spectroscopy

Electrochemical CO2 reduction (eCO2R) is a promising pathway to convert detrimental CO2 emissions into sustainable chemicals. The use of gas diffusion electrodes (GDEs) fed by gaseous CO2 enables achieving high activity and selectivity, albeit with limited stability. We recently demonstrated by operando wide-angle X-rays scattering that, during continuous electrolysis, (bi)carbonate crystals precipitate close to the catalyst, causing GDE instability. Strikingly, preliminary pulsed electrolysis experiments show that (bi)carbonate precipitation can take place without losses of GDE selectivity, leading to a 10-fold increase in GDE stability. As the catalyst can oxidize during the pulses, we propose to use operando X-rays absorption spectroscopy to investigate the role of catalyst oxidation state in controlling GDE selectivity and stability during pulsed electrolysis, as this holds the key to stable eCO2R.