Electrolyte Composition‐Dependent Product Selectivity in CO2 Reduction with a Porphyrinic Metal‐Organic Framework Catalyst

A copper porphyrin‐derived metal–organic framework electrocatalyst, FICN‐8, was synthesized and its catalytic activity for CO 2 reduction reaction (CO 2 RR) was investigated. FICN‐8 selectively catalyzed electrochemical reduction of CO 2 to CO in anhydrous acetonitrile electrolyte. However, formic acid became the dominant CO 2 RR product with the addition of a proton source to the system. Mechanistic studies revealed the change of major reduction pathway upon proton source addition, while catalyst‐bound hydride (*H) species was proposed as the key intermediate for formic acid production. This work highlights the importance of electrolyte composition on CO 2 RR product selectivity.