Advances in Understanding the Mechanism and Improved Stability of the Synthesis of Ammonia from Air and Water in Hydroxide Suspensions of Nanoscale Fe2O3
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- 作者：Fang-Fang Li ; Stuart Licht
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：October 6, 2014
- 年：2014
- 卷：53
- 期：19
- 页码：10042-10044
- 全文大小：210K
- ISSN：1520-510X
文摘
We report a mechanism of electrochemical ammonia (NH3) production via an iron intermediate in which H2 and NH3 are cogenerated by different electron-transfer pathways. Solar thermal can contribute to the energy to drive this synthesis, resulting in a STEP, solar thermal electrochemical process, for NH3. Enhancements are presented to this carbon dioxide (CO2)-free synthesis, which uses suspensions of nano-Fe2O3 in high-temperature hydroxide electrolytes at nickel and Monel electrodes. In a 200 掳C molten eutectic Na0.5K0.5OH electrolyte, the 3 Faraday efficiency per mole of synthesized NH3, 畏NH3, increases with decreasing current density, and at jelectrolysis = 200, 25, 2, and 0.7 mA cm鈥?, 畏NH3 = 1%, 7%, 37%, and 71%, respectively. At 200 mA cm鈥?, over 90% of applied current drives H2, rather than NH3, formation. Lower temperature supports greater electrolyte hydration. At 105 掳C in the hydrated Na0.5K0.5OH electrolyte, 畏NH3 increases and then is observed to be highly stable at 畏NH3 = 24(+2)%.