Site‐Specific Axial Oxygen Coordinated FeN4 Active Sites for Highly Selective Electroreduction of Carbon Dioxide.

Regulating the coordination environment via heteroatoms to break the symmetrical electronic structure of M‐N4 active sites provides a promising route to engineer metal‐nitrogen‐carbon catalysts for electrochemical CO2 reduction reaction. However, it remains challenging to realize a site‐specific introduction of heteroatoms at atomic level due to their energetically unstable nature. Here, this paper reports a facile route via using an oxygen‐ and nitrogen‐rich metal–organic framework (MOF) (IRMOF‐3) as the precursor to construct the Fe‐O and Fe‐N chelation, simultaneously, resulting in an atomically dispersed axial O‐coordinated FeN4 active site. Compared to the FeN4 active sites without O coordination, the formed FeN4‐O sites exhibit much better catalytic performance toward CO, reaching a maximum FECO of 95% at −0.50 V versus reversible hydrogen electrode. To the best of the authors' knowledge, such performance exceeds that of the existing Fe‐N‐C‐based catalysts derived from sole N‐rich MOFs. Density functional theory calculations indicate that the axial O‐coordination regulates the binding energy of intermediates in the reaction pathways, resulting in a smoother desorption of CO and increased energy for the competitive hydrogen production. [ABSTRACT FROM AUTHOR]