Insight into the effects of pulsed CO₂ electrolysis in a zero-gap electrolyzer

Electrochemical CO₂ reduction reactions face activity, selectivity, and stability challenges as this technology moves towards commercialization. Pulsed electrolysis (PE) has been shown to improve selectivity and stability at the cost of a negligible energy increase. The effectiveness of PE was assessed in a zero-gap membrane electrode assembly with a Cu catalyst between 50 and 500 mA cm^-2 with various, widely adopted binders including Nafion, Sustainion, and fluorinated ethylene propylene. PE suppresses H₂ production at 50-300 mA cm^-2 and nearly doubles the faradaic efficiency of multi-carbon products when this approach is combined with the use of Sustainion-incorporating electrodes. We find that the notable improvement can be accounted for <i>via</i> the increased local CO₂ concentration observed using <i>in situ</i> surface enhanced Raman spectroscopy.