Iron-Modified Mesoporous MOFs for Enhanced Electrochemical Nitrate-to-Ammonia Conversion

Abstract Electrocatalytic nitrate reduction is a sustainable alternative to the Haber-Bosch process, yet balancing activity with selectivity remains challenging. Herein, we developed a Fe-incorporated mesoporous UiO-66-NH2 (Fe-mUiO-66-NH2) catalyst using a hierarchical mesopore-confinement strategy. Structural analysis confirmed that the coral-like mesoporous architecture remains intact after Fe incorporation. XPS and electrochemical analyses show that the Fe sites within the mesoporous framework facilitate efficient charge transfer, which is key to the improved catalytic activity. Consequently, Fe-mUiO-66-NH2 achieves a superior ammonia yield rate of 160 μmol h-1 cm-2 and a Faradaic efficiency of 75%, representing a significant improvement over the performance of the pristine MOF. This work demonstrates the synergy between efficient mass transport and optimized intrinsic activity, offering an effective strategy for high-efficiency nitrogen cycling.