Spin polarized Fe1−Ti pairs for highly efficient electroreduction nitrate to ammonia

Abstract

Abstract Electrochemical nitrate reduction to ammonia offers an attractive solution to environmental sustainability and clean energy production but suffers from the sluggish *NO hydrogenation with the spin–state transitions. Herein, we report that the manipulation of oxygen vacancies can contrive spin−polarized Fe1−Ti pairs on monolithic titanium electrode that exhibits an attractive NH3 yield rate of 272,000 μg h−1 mgFe −1 and a high NH3 Faradic efficiency of 95.2% at −0.4 V vs. RHE, far superior to the counterpart with spin−depressed Fe1−Ti pairs (51000 μg h–1 mgFe –1) and the mostly reported electrocatalysts. The unpaired spin electrons of Fe and Ti atoms can effectively interact with the key intermediates, facilitating the *NO hydrogenation. Coupling a flow−through electrolyzer with a membrane-based NH3 recovery unit, the simultaneous nitrate reduction and NH3 recovery was realized. This work offers a pioneering strategy for manipulating spin polarization of electrocatalysts within pair sites for nitrate wastewater treatment.