@article{Hu2026, 
author = {Shan Hu and Yuxin Shi and Qiannan Bi and Xiaoyan Liu and Panzhe Qiao and Guisheng Li and Ru Zheng and Dieqing Zhang},
title = {Reconstructed low-valent Fe single-atom sites on deficient TiO2 enable electrocatalytic nitrate reduction to ammonia},
year = {2026},
journal = {Nano Research},
volume = {19},
number = {8},
pages = {94908792},
keywords = {electrocatalysis, ammonia synthesis, nitrate reduction reaction, metal single-atom},
url = {https://www.sciopen.com/article/10.26599/NR.2026.94908792},
doi = {10.26599/NR.2026.94908792},
abstract = {Electrochemical nitrate (NO3−) reduction reaction (NO3RR) offers a promising route for NO3− remediation and sustainable ammonia (NH3) synthesis, yet its efficiency is often constrained by the hydrogenation of nitrogen-containing intermediates. Herein, we report Fe single atoms anchored on oxygen-vacancy-rich TiO2 nanosheet assemblies (FeSA-TiO2-Ov) for efficient NO3− to NH3 conversion. The FeSA-TiO2-Ov catalyst achieves a high NH3 yield rate of 16.6 mg·h−1·cm−2 at −0.5 V versus reversible hydrogen electrode (vs. RHE), accompanied by a maximum Faradaic efficiency of 92% and excellent durability over 40 h. Operando X-ray absorption fine structure (XAFS) spectroscopy reveals a gradual decrease in Fe valence and contraction of the Fe–O coordination shell, confirming the formation of reconstructed low-valent Fe single-atom active sites during NO3RR. Theoretical calculations and spectroscopic analysis further indicate that Fe sites are effective for *NO hydrogenation to the *NOH intermediate, thereby promoting the efficient formation of NH3. These findings identify the reconstructed low-valent Fe single atoms as the active sites for selective electrosynthesis of NH3, providing a mechanistic framework for designing single-atom catalysts applicable to multistep electrocatalytic reduction reactions.}
}