Synthesis of Hydroxylamine via Ketone-Mediated Nitrate Electroreduction

Shunhan Jia; Limin Wu; Xingxing Tan; Jiaqi Feng; Xiaodong Ma; Libing Zhang; Xinning Song; Liang Xu; Qinggong Zhu; Xinchen Kang; Xiaofu Sun; Buxing Han

doi:10.1021/jacs.4c01961

Synthesis of Hydroxylamine via Ketone-Mediated Nitrate Electroreduction

J Am Chem Soc. 2024 Apr 17;146(15):10934-10942. doi: 10.1021/jacs.4c01961. Epub 2024 Apr 6.

Authors

Shunhan Jia^{1

2}, Limin Wu^{1

2}, Xingxing Tan¹, Jiaqi Feng^{1

3}, Xiaodong Ma¹, Libing Zhang^{1

2}, Xinning Song^{1

2}, Liang Xu^{1

4}, Qinggong Zhu^{1

2}, Xinchen Kang^{1

2}, Xiaofu Sun^{1

2}, Buxing Han^{1

2

5}

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, CAS Laboratory of Colloid and Interface and Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Center for Carbon Neutral Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
² School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, PR China.
³ College of Chemical Engineering and Environment, China University of Petroleum, Beijing 102249, China.
⁴ State Key Laboratory of Organic-Inorganic Composites, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
⁵ Shanghai Key Laboratory of Green Chemistry and Chemical Processes, State Key Laboratory of Petroleum Molecular & Process Engineering, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.

PMID: 38581437
DOI: 10.1021/jacs.4c01961

Abstract

Hydroxylamine (HA, NH₂OH) is a critical feedstock in the production of various chemicals and materials, and its efficient and sustainable synthesis is of great importance. Electroreduction of nitrate on Cu-based catalysts has emerged as a promising approach for green ammonia (NH₃) production, but the electrosynthesis of HA remains challenging due to overreduction of HA to NH₃. Herein, we report the first work on ketone-mediated HA synthesis using nitrate in water. A metal-organic-framework-derived Cu catalyst was developed to catalyze the reaction. Cyclopentanone (CP) was used to capture HA in situ to form CP oxime (CP-O) with C═N bonds, which is prone to hydrolysis. HA could be released easily after electrolysis, and CP was regenerated. It was demonstrated that CP-O could be formed with an excellent Faradaic efficiency of 47.8%, a corresponding formation rate of 34.9 mg h^-1 cm^-2, and a remarkable carbon selectivity of >99.9%. The hydrolysis of CP-O to release HA and CP regeneration was also optimized, resulting in 96.1 mmol L^-1 of HA stabilized in the solution, which was significantly higher than direct nitrate reduction. Detailed in situ characterizations, control experiments, and theoretical calculations revealed the catalyst surface reconstruction and reaction mechanism, which showed that the coexistence of Cu⁰ and Cu⁺ facilitated the protonation and reduction of *NO₂ and *NH₂OH desorption, leading to the enhancement for HA production.