Hu Qikun, Yang Ke, Peng Ouwen, Li Minzhang, Ma Lu, Huang Songpeng, Du Yonghua, Xu Zong-Xiang, Wang Qing, Chen Zhongxin, Yang Ming, Loh Kian Ping
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China.
J Am Chem Soc. 2024 Jan 10;146(1):668-676. doi: 10.1021/jacs.3c10516. Epub 2023 Dec 28.
Electrochemical synthesis of ammonia via the nitrate reduction reaction (NO3RR) has been intensively researched as an alternative to the traditional Haber-Bosch process. Most research focuses on the low concentration range representative of the nitrate level in wastewater, leaving the high concentration range, which exists in nuclear and fertilizer wastes, unexplored. The use of a concentrated electrolyte (≥1 M) for higher rate production is hampered by poor hydrogen transfer kinetics. Herein, we demonstrate that a cocatalytic system of Ru/CuO catalyst enables NO3RR at 10.0 A in 1 M nitrate electrolyte in a 16 cm flow electrolyzer, with 100% faradaic efficiency toward ammonia. Detailed mechanistic studies by deuterium labeling and Fourier transform infrared (FTIR) spectroscopy allow us to probe the hydrogen transfer rate and intermediate species on Ru/CuO. molecular dynamics (AIMD) simulations reveal that adsorbed hydroxide on Ru nanoparticles increases the density of the hydrogen-bonded water network near the CuO surface, which promotes the hydrogen transfer rate. Our work highlights the importance of engineering synergistic interactions in cocatalysts for addressing the kinetic bottleneck in electrosynthesis.
通过硝酸盐还原反应（NO3RR）进行电化学合成氨作为传统哈伯-博施法的替代方法已得到深入研究。大多数研究集中在代表废水中硝酸盐水平的低浓度范围，而存在于核废料和肥料废料中的高浓度范围尚未得到探索。使用浓电解质（≥1 M）以实现更高的产率受到氢转移动力学不佳的阻碍。在此，我们证明了Ru/CuO催化剂的共催化体系能够在16厘米流动电解槽中的1 M硝酸盐电解质中以10.0 A的电流实现NO3RR，对氨的法拉第效率为100%。通过氘标记和傅里叶变换红外（FTIR）光谱进行的详细机理研究使我们能够探究Ru/CuO上的氢转移速率和中间物种。分子动力学（AIMD）模拟表明，Ru纳米颗粒上吸附的氢氧化物增加了CuO表面附近氢键水网络的密度，从而促进了氢转移速率。我们的工作突出了设计共催化剂中的协同相互作用对于解决电合成中的动力学瓶颈的重要性。
