A Versatile Method for Ammonia Detection in a Range of Relevant Electrolytes via Direct Nuclear Magnetic Resonance Techniques
A Versatile Method for Ammonia Detection in a Range of Relevant Electrolytes via Direct Nuclear Magnetic Resonance Techniques
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DOI：
10.1021/acscatal.9b00358
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发表时间：
2019-07-01
期刊：
影响因子：
12.9
通讯作者：
Jaramillo, Thomas F.
中科院分区：
文献类型：
--
作者：
Nielander, Adam C.;McEnaney, Joshua M.;Jaramillo, Thomas F.
电催化N-2还原成氨作为Haber-Bosch过程的可能的可再生能源驱动的替代方案最近引起了极大的兴趣。然而，在尝试电催化还原N-2之后检测NH3可能受到低NH3产率、环境NH3污染以及需要从电解质中多步化学分离NH3的阻碍。在此，我们报告了一种频率选择性脉冲核磁共振（NMR）方法，并量化了这种方法测量电催化后电解质中NH3（在测定中作为NH 4+存在）浓度的功效。这种NMR方法被证明是有效的，在各种nondeuterated，非水和水性电解质，并不需要从电解质中分离NH3。NH3的灵敏度下降到1 μ M，很容易实现同位素和化学特异性。相容的电解质和溶剂包括乙醇、四氢呋喃、二甲亚砜、乙腈、碳酸丙烯酯、二乙基二乙酯、己烷和水。还对常用的Berthelot方法的功效进行了定量，并与NMR方法在一系列非水性和水性电解质（包括乙醇、THF、碳酸丙烯酯和水）中进行了比较。
Electrocatalytic N-2 reduction to ammonia has recently attracted a great deal of interest as a possible renewable energy-driven alternative to the Haber-Bosch process. However, the detection of NH3 after attempting electrocatalytic reduction of N-2 can be hampered by low NH3 yields, ambient NH3 contamination, and the need for multistep chemical separation of NH3 from the electrolyte. Herein, we report a frequency-selective pulse nuclear magnetic resonance (NMR) method and quantify the efficacy of this method to measure the concentration of NH3 (present in the assay as NH4+) in an electrolyte after electrocatalysis. This NMR method was demonstrated to be effective in a variety of nondeuterated, nonaqueous and aqueous electrolytes, and did not require the separation of NH3 from the electrolyte. NH3 sensitivity down to 1 mu M was readily achieved with isotopic and chemical specificity. Compatible electrolytes and solvents included ethanol, tetrahydrofuran, dimethyl sulfoxide, acetonitrile, propylene carbonate, diethyl either, hexanes, and water. The efficacy of the commonly employed Berthelot method was also quantified and compared to the NMR method in a range of nonaqueous and aqueous electrolytes, including ethanol, THF, propylene carbonate, and water.