Electrocatalytic conversion of nitrates to produce high-value-added NH₃ exhibited promise as a replacement for the Haber–Bosch process due to the involvement of an eight-electron and nine-proton transfer in the electrocatalytic nitrate reduction reaction (NO₃RR), which exhibits low Faradaic efficiency and selectivity toward NH₃. Herein, a cobalt molybdate catalyst was in situ grown on nickel foam with abundant oxygen vacancies and a rich unsaturated coordination Mo⁴⁺ environment by a rapid Joule heating method. The synergistic optimization of these features modulated the overall catalyst electronic structure, achieving both high activity and high selectivity in NO₃RR. Specifically, in an electrolyte of 0.1 M K₂SO₄ and 1000 mg_NO3^–/L, a Faradaic efficiency of 94.6% and a NH₃ yield rate of 1.32 mg h^–1 cm^–2 were achieved at −0.35 V vs RHE. Meanwhile, the selectivity of NH₃ reached 97% after the 12 h test. In six consecutive cycles and during a 12 h extended stability assessment, the CMO/NF-800 catalyst consistently exhibited exceptional chemical stability. DFT results demonstrated that nitrate adsorption and ammonia desorption were more readily achieved on the surface of the CMO/NF-800 and that there was a lower energy barrier that needed to be overcome for RDS. This work provided a reservable approach to the preparation of catalysts with abundant unsaturated coordination environments on the highly selective electroreduction of nitrate into ammonia.

中文翻译：

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焦耳热合成不饱和Mo4+配位钼酸钴，大幅增强电催化硝酸盐还原制氨

_{由于电催化硝酸盐还原反应（NO 3} RR）中涉及八电子和九质子转移，电催化转化硝酸盐生产高附加值NH ₃有望替代哈伯-博世工艺，其表现出低法拉第效率和对NH _{3 的}选择性。本文采用快速焦耳加热法在具有丰富氧空位和丰富不饱和配位Mo ⁴⁺环境的泡沫镍上原位生长钼酸钴催化剂。这些特性的协同优化调节了催化剂的整体电子结构，实现了NO ₃ RR的高活性和高选择性。具体而言，在0.1 MK ₂ SO ₄和1000 mg _NO3 ^– /L的电解质中，在-0.35 V vs RHE下实现了94.6%的法拉第效率和1.32 mg h ^–1 cm ^–2的NH ₃产率。同时，经过12 h的测试， NH_{​​ 3}的选择性达到了97%。在六个连续循环和 12 小时延长稳定性评估中，CMO/NF-800 催化剂始终表现出卓越的化学稳定性。 DFT 结果表明，CMO/NF-800 表面更容易实现硝酸盐吸附和氨解吸，并且 RDS 需要克服的能垒较低。该工作为制备具有丰富不饱和配位环境的高选择性硝酸盐电还原成氨催化剂提供了一种可借鉴的方法。