Creating Anionic Microenvironment Around Single‐Atom Fe Sites in Metal–Organic Frameworks for Enhanced Nitrate Electroreduction

ABSTRACT The electrocatalytic nitrate reduction reaction (eNO 3 RR) offers a sustainable strategy for both NO 3 − wastewater remediation and value‐added NH 3 production. However, its application is hindered by sluggish reaction kinetics in neutral media due to the limited availability of protons. Herein, an anionic metal–organic framework (MOF), SU‐102, is functionalized with atomically dispersed Fe sites to yield SU‐102‐Fe. This catalyst achieves a Faradaic efficiency (FE) of 96.9% and NH 3 production rate of 1.72 mg h −1 mg cat −1 at −0.7 V versus RHE, far surpassing the commercial Fe 2 O 3 and pristine SU‐102. In situ characterizations reveal that the negatively charged Zr─O units in SU‐102 create an anionic microenvironment around the Fe sites, which enriches K + •H 2 O species derived from the interfacial hydrogen‐bonding network. The facile dissociation of K + •H 2 O improves local proton supply, facilitating NO 3 − ‐to‐NH 3 conversion and accounting for the superior eNO 3 RR performance of SU‐102‐Fe.