Laser-Microstructured Copper Reveals Selectivity Patterns in the Electrocatalytic Reduction of CO2

Summary The strategy of engineering the local chemical environment to direct selectivity in the electroreduction of CO2 toward value-added products is only qualitatively understood. The unfeasibility of local concentration measurements and the limited applicability of simulations to practical systems hinder more precise guidelines. Here, we quantify the impact of the (electro)chemical environment on the selectivity pattern by using microstructured copper (Cu) electrodes prepared by ultra-short pulse laser ablation. We created regularly distributed micro-probes and assessed their product distributions at distinct overpotentials. The regular geometry enabled the accurate simulation of the local pH and CO2 concentration. Selectivity maps useful for mechanistic and applied studies emerged. They revealed clear patterns for C1–C3 products, suggesting novel insights, such as the presence of two reaction mechanisms for propanol. The effect on the selectivity pattern of operating parameters, such as enhanced mass transport and electrolyte composition, was also predicted by the maps.