Efficient Ammonia Production Beginning from Enhanced Air Activation
Zhe Meng, Jiaxin Yao, Changning Sun, Kang Xia, Rui Gao, Hong‐Rui Li, Bo Bi, Yong‐Fu Zhu, Jun‐Min Yan, Qing Jiang
Abstract
Abstract Ammonia is considered to be a next‐generation clean energy carrier, and thus the green synthesis of NH 3 is of great importance. In this work, non‐thermal plasma oxidation is combined with electroreduction to achieve an efficient two‐step NH 3 synthesis. A Ti bubbler is introduced in the first step of plasma activation of air to effectively produce nitrate/nitrite (NO x − ) in an absorption solution, and the production rate achieves the highest value of 55.29 mmol h −1 ; the obtained NO x − aqueous solution is directly employed as catholyte for the second step of electroreduction with oxygen vacancy‐rich Co 3 O 4 nanoparticles as the catalyst. Density functional theory calculations reveal that the introduction of oxygen vacancies endows their adjacent Co atoms with improved activity, which promotes adsorption and hydrogenation of NO x − , meanwhile suppressing the hydrogen evolution reaction. Thus the oxygen vacancy‐rich Co 3 O 4 NPs present a significant NH 3 production rate of 39.60 mg h −1 cm −2 , high Faradaic efficiency of 96.08% and a large current density (376.48 mA cm −2 ), outperforming the previously reported ones including N 2 or NO x − electroreduction.