Pulsed electrolysis controls copper restructuring via dissolution–redeposition to prolong selective CO2 reduction to ethylene

Pulsed electrolysis is known to enhance the stability of electrochemical CO 2 reduction (ECO 2 R) on copper, yet the mechanistic origin of this effect remains poorly understood. Using identical-location electron microscopy in combination with operando impedance spectroscopy, we show that pulsed operation induces continuous and dynamic restructuring of the copper surface. Over 23 h of electrolysis, the catalyst evolved from its initial morphology into a grain-like architecture decorated with dendritic features enriched in high-index facets. This structural evolution was accompanied by a steady increase in the ethylene-to-hydrogen selectivity ratio. Quantitative analysis of the electrolyte during pulsed electrolysis revealed an approximately 30-fold increase in dissolved copper species compared to static operation, identifying redirected dissolution–redeposition of copper as the central mechanistic pathway by which pulsing governs morphology evolution and, consequently, ECO 2 R selectivity. ● Pulsed CO₂ electroreduction redirects copper dissolution–redeposition dynamics. ● Operando EIS and IL-SEM link copper restructuring to stability and selectivity. ● Pulsing sustains ethylene selectivity for one day without activity loss. ● Oxidation–reduction cycles induce dendritic copper growth. ● Stability arises from controlled catalyst instability, not structural suppression.