DOI: 10.1002/adma.73761 ISSN: 0935-9648

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

Heng Yue, Wan Xie, Da Wan, Huizhu Cai, Xue Zhang, Qi Hu, Hengpan Yang, Chuanxin He
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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.

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