Fe3 +-induced interfacial electronic effects in UiO-66 for enhanced electrocatalytic nitrate-to-ammonia conversion

A general strategy to enhance NO 3 RR performance is proposed by incorporating Lewis-acidic ions into the UiO-66. • Fe-UiO-66 exhibits enhanced NO 3 RR performance, achieving an NH 3 yield rate of 2.34 mg h −1 cm −2 at −0.69 V vs. RHE. • Fe incorporation facilities H 2 O activation and promotes the generation and utilization of surface *H. • Key reaction intermediates are captured by in-situ FTIR spectroscopy and DEMS, confirming the proposed reaction pathway. Electrochemical nitrate reduction (NO 3 RR) is a promising approach for decentralized ammonia synthesis, yet its efficiency is limited by sluggish nitrate activation and competing hydrogen evolution (HER). Inspired by electronic structure modulation, a strategy is presented in which Lewis-acidic ions are incorporated into the UiO-66 framework to promote NO 3 RR kinetics. Among, Fe-UiO-66 demonstrates substantially enhanced NO 3 RR performance, delivering an NH 3 yield of 2.34 mg h −1 cm −2 with a Faradaic efficiency (FE) of 96.25% at −0.69 V vs. RHE, corresponding to nearly a 13-fold increase relative to pristine UiO-66 (0.179 mg h −1 cm −2 , 33.36%). Experimental and theoretical analyses reveal that the Fe incorporation induces local electronic reconstruction and electron accumulation at the Fe centers, thereby strengthening NO 3 - adsorption and facilitating its activation. Moreover, electrochemical and isotope labeling results indicate that Fe incorporation facilitates H 2 O activation and promotes the generation and utilization of surface *H, thereby accelerating the hydrogenation of nitrogen-containing intermediates. In-situ FTIR spectroscopy together with online DEMS identifies the key reaction intermediates, supporting the proposed reaction pathway. This work highlights electronic structure reconstruction as an effective strategy for regulating nitrate adsorption and subsequent intermediate hydrogenation, providing mechanistic insights and design guidance for efficient MOF-based NO 3 RR electrocatalysts. Download: Download high-res image (213KB) Download: Download full-size image