Operational strategies of pulsed electrolysis to enhance multi-carbon product formation in electrocatalytic CO2 reduction†

The electrocatalytic reduction of CO₂ offers a promising avenue for converting anthropogenic CO₂ into valuable chemical and fuel feedstocks. Copper (Cu) catalysts have shown potential in this regard, yet challenges persist in achieving high selectivity for multi-carbon (C₂₊) products. Pulsed electrolysis, employing alternating anodic and cathodic potentials (E_a/E_c) or two different cathodic potentials (E_c1/E_c2), presents a promising approach to modulate activity and selectivity. In this study, we investigate the influence of catalyst morphology and operational strategies on C₂₊ product formation using Cu nanoparticles (NPs) and CuO nanowires (NWs) in flow cells. In E_a/E_c mode, commercial Cu NPs show negligible promotion of C₂₊ selectivity while CuO NWs demonstrate enhanced C₂₊ selectivity attributed to facile oxidation/redox cycling and grain boundary formation. In contrast, E_c1/E_c2 pulsed electrolysis promotes C₂₊ yield across various catalyst morphologies by enhancing CO₂ accumulation, pH effect, and supplemental CO utilization. We further extend our investigation to membrane electrode assembly cells, highlighting the potential for scalability and commercialization. Our findings underscore the importance of catalyst morphology and operational strategies in optimizing C₂₊ product formation pulsed electrolysis, laying the groundwork for future advancements in CO₂ electroreduction technologies.