Tailoring electrochemical CO2 reduction selectivity over CuSn by modulating surface oxidation state with infrared laser treatment

Infrared laser treatment was used to precisely modify the surface structure of CuSn electrodes, effectively finetuning the selectivity of reduction products. With increasing laser power, the metallic Cu and Sn surfaces became more oxidized, and the Sn/Cu composition ratio varied with depth and further changed post-EC reaction. The diversity of reduction products, including C1 (CO, CH4, and formate), C2 (C2H4, ethanol, acetate, acetaldehyde, and glycolaldehyde), and C3 (propanol and isopropanol) compounds, shifted towards a more selective production of C1 (CO and formate) products. These tailored behaviors are attributed to variations in interfacial electronic structures, oxidation states, composition ratios, and the interaction between CO2 and the density of states (Cu, O, and Sn) near the Fermi level. The laser treatment method enables precise tuning of electrode surfaces, modulation of reduction products, and enhancement of selectivity. Moreover, this technique presents a novel approach for electrode design in the field of CO2 reduction, offering new avenues for optimizing catalytic performance.