Tuning Intermediate Adsorption and Interfacial Water Networks via Lattice Strain of NiFe Alloys Boosts Low‐Concentration Nitrate Electroreduction

Abstract

ABSTRACT The electrochemical nitrate‐to‐ammonia reduction (NO 3 − RR) in low‐concentration neutral media is often hindered by sluggish mass transfer and competitive hydrogen evolution reaction (HER). Herein, we propose a strategy to introduce lattice strain into a Ni catalyst through the co‐evaporation of a small proportion of Fe heteroatoms. According to in situ spectroscopy and theoretical calculations, the strain effect can optimize the d ‐band center of the Ni active sites, thereby modulating the adsorption strength of key intermediates ( * NO 3 − , * NO 2 , * NO) and enhancing the intrinsic activity for NO 3 − RR. Furthermore, the strained surface can reorganize the interfacial hydrogen‐bond network and modulate the proportion of free water, thereby balancing the supply of active hydrogen ( * H) with the suppression of HER. Consequently, NiFe‐T1.4 achieves remarkable NH 3 Faradaic efficiencies (FE) up to 95.5% and yield rates up to 8.57 mg h −1 cm −2 in neutral low‐concentration (5–50 m m ) nitrate solutions. Furthermore, NiFe‐T1.4 can also be employed as a cathode in a Zn‐NO 3 − battery, delivering a high open‐circuit voltage of 1.53 V and a peak power density of 8.10 mW cm −2 . This work presents a feasible approach to engineering high‐performance catalysts for nitrate‐to‐ammonia conversion by combining lattice strain and interfacial water management.