Isomeric Cu(I) Azolate Frameworks Showing Contrasting Electrocatalytic CO2 Reduction Selectivities and Stabilities

Abstract Metal‒organic frameworks have attracted wide interest in the electrocatalytic CO 2 reduction reaction (eCO 2 RR), but their differences of performances originated from chemical composition and stabilities are rarely concerned. Here, isomeric Cu(I) triazolate frameworks (MAF‐2Fa and MAF‐2Fb) with similar thermal/chemical stabilities but very different coordination modes are used for eCO 2 RR studies. MAF‐2Fa with monotypic planar dinuclear Cu(I) coordination mode achieves high selectivity for C 2 H 4 (53%) and C 2 products (70%), with almost unchanged over a wide potential window (‒1.1 to ‒1.5 V), making it among one of the best Cu‐complex electrocatalysts. In contrast, MAF‐2Fb with multiple Cu(I) coordination modes (including planar/bent dinuclear, linear mononuclear, and trigonal mononuclear ones) showed low C 2 /C 1 products without significant differences. More interestingly, MAF‐2Fa can maintain its performance for at least 8 h, whereas MAF‐2Fb decomposed into inorganics with inferior performance after 1.5 h. The significant differences of eCO 2 RR selectivities and stabilities are elucidated by computational simulations and operando electrochemical tests.