Proton Donors Induce a Differential Transport Effect for Selectivity toward Ammonia in Lithium-Mediated Nitrogen Reduction
Proton Donors Induce a Differential Transport Effect for Selectivity toward Ammonia in Lithium-Mediated Nitrogen Reduction
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DOI：
10.1021/acscatal.2c00389
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发表时间：
2022-05-06
期刊：
影响因子：
12.9
通讯作者：
Manthiram, Karthish
中科院分区：
文献类型：
--
作者：
Lazouski, Nikifar;Steinberg, Katherine J.;Manthiram, Karthish
生产氨的替代方法是必要的，以减少其生产对环境的影响。锂介导的电化学氮还原反应（LM-NRR）是一种有吸引力的小尺度分布式制氨方法。该过程需要电解质中的质子供体从氮中产生氨，但质子供体在选择性氨生产中的作用尚不清楚。在这项工作中，我们通过实验测试了几种质子供体促进LM-NRR的能力。我们发现许多醇都可以促进氮还原，而正丁醇导致最高的氨法拉第效率。在被测质子供体中，即使质子供体结构的微小变化也会显著影响氨的产率。此外，大多数活性质子供体表现出阈值行为，作为其浓度的函数，其中对氨的选择性在质子供体的一定浓度以上显着增加。我们发现的证据表明，这些影响可能是由于质子供体诱导的固体电解质间相（SET）性质的变化，导致相关物质通过SEI扩散到反应电极的变化。通过选择性地允许氮在质子供体上扩散到电极，SEI可以促进选择性氮还原为氨。提出了该过程的耦合动力学输运模型来解释观察到的趋势，并预测氨产量作为操作条件的函数。
Alternative approaches for producing ammonia are necessary to reduce the environmental impact of its production. The lithium-mediated electrochemical nitrogen reduction reaction (LM-NRR) is one attractive alternative method for producing ammonia at small scales in a distributed process. This process requires a proton donor in the electrolyte to produce ammonia from nitrogen, but the role of the proton donor in selective ammonia production is not well understood. In this work, we experimentally tested several classes of proton donors for the ability to promote LM-NRR We found that a wide array of alcohols can promote nitrogen reduction and that n-butanol leads to the highest ammonia Faradaic efficiencies. Among the tested proton donors, even slight changes in the proton donor structure can significantly affect the yield of ammonia. In addition, most active proton donors exhibit a thresholding behavior as a function of their concentration, where the selectivity toward ammonia increases dramatically above a certain concentration of the proton donor. We found evidence to imply that these effects could be due to the proton-donor-induced changes in the properties of the solid electrolyte interphase (SET), which lead to changes in the diffusion of relevant species through the SEI to the reactive electrode. By selectively allowing for diffusion of nitrogen over the proton donor to the electrode, the SEI can promote selective nitrogen reduction to ammonia. A coupled kinetic transport model of the process was proposed to explain the observed trends and to predict ammonia production as a function of operating conditions.