Rational Fluorination of Pyrazolate MOFs: Unlocking High-Efficiency Acetate Electrosynthesis via CO Reduction

Electrochemical carbon monoxide reduction (eCORR) to acetate, an indispensable molecular scaffold, represents a paradigm-shifting strategy for the synthesis of acetate under ambient conditions. The pursuit of advanced electrocatalytic systems enabling efficient multi-electron transfer pathways remains critical to achieve selective eCORR toward sustainable acetate synthesis. In this study, one fluorine-substituted pyrazole-based metal–organic framework (CuPz-F) was obtained. It showed an outstanding eCORR performance, achieving a remarkable C₂₊ Faradaic efficiency of 83.5% and an acetate FE of 45.8%, corresponding to a high acetate partial current density of 249.7 mA cm⁻² and a turnover frequency of 1131 h⁻¹. Comprehensive mechanistic studies demonstrate that pyrazole ligands shorten Cu─Cu distances, lowering the energy barrier for C─C coupling. Concurrently, fluorine substitution electronically stabilizes Cu²⁺ centers, thereby strengthening CO adsorption—an essential prerequisite for C─C bond formation. Moreover, F substituents promote water dissociation and enable hydrogen spillover to adjacent Cu sites. Together, electronic modulation, optimized Cu─Cu proximity, and hydrogen spillover synergistically underpin the enhanced eCORR activity toward acetate production. This work provides new insights into the influence of the F substituent in the MOFs' electrocatalysts on eCORR performance, and is highly instructive for the rational design of next-generation, high-efficiency electrocatalysts for CO.