Subtle Modifications in Interface Configurations of Iron/Cobalt Phthalocyanine-based Electrocatalysts Determine Molecular CO2 Reduction Activities

Strain engineering has emerged as a powerful approach in steering the material properties. However, the improved catalytic activity remains poorly understood. Here we report that subtle changes in molecular configurations can profoundly affect, conducively or adversely, the catalytic selectivity and product turnover frequencies (TOFs) of CO2RR. Specifically, introducing molecular curvature in cobalt tetraaminophthalocyanine improves the multielectron CO2RR activity by favorable *CO hydrogenation, attaining methanol Faradaic efficiency up to 52%. In stark contrast, strained iron phthalocyanine exacerbates *CO poisoning, leading to a decreased TOFCO by over 50% at -0.5 VRHE and a rapid current decay. The uniform dispersion is crucial for optimizing electron transfer, while activity is distinctly sensitive to local atomic environment around the active sites. Specifically, local strain either enhances binding to intermediates or poisons the catalytic sites. Our comprehensive analysis elucidates the intricate relationship between molecular structure and CO2RR activities, offering insights into designing efficient heterogeneous molecular interfaces.