Enhancing the rate of electrochemical nitrogen reduction reaction for ammonia synthesis under ambient conditions using hollow gold nanocages
Enhancing the rate of electrochemical nitrogen reduction reaction for ammonia synthesis under ambient conditions using hollow gold nanocages
复制标题
DOI：
10.1016/j.nanoen.2018.04.039
复制
发表时间：
2018-07-01
期刊：
影响因子：
17.6
通讯作者：
El-Sayed, Mostafa A.
中科院分区：
文献类型：
--
作者：
Nazemi, Mohammadreza;Panikkanvalappil, Sajanlal R.;El-Sayed, Mostafa A.
为了增加不断增长的全球人口的粮食供应，氨气生产势在必行。氨也被认为是氢能的主要载体。目前工业生产氨的方法是能源密集型的，严重依赖化石燃料，而化石燃料是环境污染的罪魁祸首。为了满足氨的需求，有必要开发可持续和环境友好的生产方法，比目前的方法消耗的能源要少得多。在环境条件下，在电化学系统中使用纳米催化可以为化肥生产提供一条替代路线。本文评价了中空纳米金(AuHNCs)作为一种有效的电催化剂在常温下用于电化学氮气还原反应(NRR)的性能。用AuHNCs在0.5M LiClO4水溶液中进行了不同电位下的电化学实验，测定了它们对氮气转化为氨的催化效率。在-0.4V对RHE时，氨法拉第效率最高(30.2%)，在-0.5V对RHE时，氨产率最高(3.9微克厘米-2小时-1)。这些值大于目前文献中报道的在环境条件下的水溶液中的最高值。此外，还评估了温度对电化学NRR性能的影响。结果表明，当反应温度从20℃提高到50℃时，氨法拉第效率从20℃时的30.2%提高到50℃时的40.5%。通过与不同形状的固体Au纳米粒子(如棒状、球状或立方体)的电催化活性的比较，阐明了比表面积的增加和限制效应对反应速率的提高。使用Au纳米立方体的氨法拉第效率(30.2%)比固体Au纳米立方体(11.4%)提高了三倍。
Ammonia production is imperative to increase the food supply for the growing global population. Ammonia is also considered a major hydrogen energy carrier. The current industrial method for ammonia production is energy intensive and heavily relies on fossil fuels, which are responsible for environmental pollution. To meet ammonia demands, it is necessary to develop sustainable and environmentally friendly production methods that consume significantly less energy than the current methods. The use of nanocatalysis in an electrochemical system under ambient conditions can make an alternative route for fertilizer production. Here, the use of hollow gold nanocages (AuHNCs) as an effective electrocatalyst is evaluated for electrochemical nitrogen reduction reaction (NRR) under ambient conditions. The electrochemical experiments are carried out at various potentials in 0.5M LiClO4 aqueous solution using AuHNCs, and their catalytic efficiency is determined for the conversion of nitrogen to ammonia. The highest ammonia Faradaic efficiency (30.2%) is achieved at -0.4 V vs. RHE while the highest ammonia yield (3.9 mu g cm(-2) h(-1)) is obtained at -0.5 V vs. RHE. These are greater than the highest values currently reported in the literature in aqueous solution under ambient conditions. Furthermore, the role of temperature on the electrochemical NRR performance is evaluated. It is found that by increasing the operating temperature from 20 degrees C to 50 degrees C at -0.4 V vs. RHE, the ammonia Faradaic efficiency increases from 30.2% at 20 degrees C to 40.5% at 50 degrees C. The electrocatalytic activity of NRR using AuHNCs is further compared with that of solid Au nanoparticles of various shapes (i.e., rods, spheres or cubes) to elucidate the enhanced rate of the reaction resulting from the increase in surface area and confinement effects. The three-fold enhancement in ammonia Faradaic efficiency is achieved by using the AuHNCs (30.2%) compared to the solid Au nanocubes (11.4%).