Electrostatic Secondary‐Sphere Interactions That Facilitate Rapid and Selective Electrocatalytic CO<sub>2</sub> Reduction in a Fe‐Porphyrin‐Based Metal–Organic Framework
Ran Shimoni, Zhuocheng Shi, Shahar Binyamin, Yang Yang, Itamar Liberman, Raya Ifraemov, Subhabrata Mukhopadhyay, Liwu Zhang, Idan Hod
Abstract
Abstract Metal–organic frameworks (MOFs) are promising platforms for heterogeneous tethering of molecular CO 2 reduction electrocatalysts. Yet, to further understand electrocatalytic MOF systems, one also needs to consider their capability to fine‐tune the immediate chemical environment of the active site, and thus affect its overall catalytic operation. Here, we show that electrostatic secondary‐sphere functionalities enable substantial improvement of CO 2 ‐to‐CO conversion activity and selectivity. In situ Raman analysis reveal that immobilization of pendent positively‐charged groups adjacent to MOF‐residing Fe‐porphyrin catalysts, stabilize weakly‐bound CO intermediates, allowing their rapid release as catalytic products. Also, by varying the electrolyte's ionic strength, systematic regulation of electrostatic field magnitude was achieved, resulting in essentially 100 % CO selectivity. Thus, this concept provides a sensitive molecular‐handle that adjust heterogeneous electrocatalysis on demand.