02 January 2024 | Jie Dai, Yawen Tong, Long Zhao, Zhiwei Hu, Chien-Te Chen, Chang-Yang Kuo, Guangming Zhan, Jianxian Wang, Xingyue Zou, Qian Zheng, Wei Hou, Ruizhao Wang, Kaiyuan Wang, Rui Zhao, Xiang-Kui Gu, Yancai Yao & Lizhi Zhang
This study reports the development of spin-polarized Fe1–Ti pairs on a monolithic titanium electrode for highly efficient nitrate reduction to ammonia (NITRR). By manipulating oxygen vacancies in the titanium oxide layer, the unpaired spin electrons of Fe and Ti atoms are induced, facilitating the deoxygenation of nitrate and the hydrogenation of nitric oxide (NO). The resulting spin-polarized Fe1–Ti pairs exhibit an impressive NH3 yield rate of 272,000 μg h−1 mgFe−1 and a high Faradaic efficiency of 95.2% at −0.4 V vs. RHE, outperforming both spin-depressed Fe1–Ti pairs and other reported electrocatalysts. The enhanced performance is attributed to the interaction of unpaired spin electrons with key intermediates, which stabilizes the deoxygenation of nitrate and accelerates the hydrogenation of NO. Additionally, the monolithic electrode was integrated with a flow-through electrolyzer and a membrane-based NH3 recovery unit, enabling simultaneous nitrate reduction and NH3 recovery from nitrate-containing wastewater. This work provides a pioneering strategy for manipulating spin polarization in electrocatalysts for environmental sustainability and clean energy production.This study reports the development of spin-polarized Fe1–Ti pairs on a monolithic titanium electrode for highly efficient nitrate reduction to ammonia (NITRR). By manipulating oxygen vacancies in the titanium oxide layer, the unpaired spin electrons of Fe and Ti atoms are induced, facilitating the deoxygenation of nitrate and the hydrogenation of nitric oxide (NO). The resulting spin-polarized Fe1–Ti pairs exhibit an impressive NH3 yield rate of 272,000 μg h−1 mgFe−1 and a high Faradaic efficiency of 95.2% at −0.4 V vs. RHE, outperforming both spin-depressed Fe1–Ti pairs and other reported electrocatalysts. The enhanced performance is attributed to the interaction of unpaired spin electrons with key intermediates, which stabilizes the deoxygenation of nitrate and accelerates the hydrogenation of NO. Additionally, the monolithic electrode was integrated with a flow-through electrolyzer and a membrane-based NH3 recovery unit, enabling simultaneous nitrate reduction and NH3 recovery from nitrate-containing wastewater. This work provides a pioneering strategy for manipulating spin polarization in electrocatalysts for environmental sustainability and clean energy production.