Ambient Electrosynthesis of Ammonia: Electrode Porosity and Composition Engineering

Wang, H (Wang, Hong)^[ 1 ] ; Wang, L (Wang, Lu)^{[ 2,3,4,5 ]} ; Wang, Q (Wang, Qiang)^[ 6 ] ; Ye, SY (Ye, Shuyang)^[ 2,3,4 ] ; Sun, W (Sun, Wei)^[ 2,3,4 ] ; Shao, Y (Shao, Yue)^[ 1 ] ; Jiang, ZP (Jiang, Zhiping)^[ 1 ] ; Qiao, Q (Qiao, Qiao)^[ 7,8 ] ; Zhu, YM (Zhu, Yimei)^[ 8 ] ; Song, PF (Song, Pengfei)^[ 9 ] ; Li, DB (Li, Debao)^[ 6 ] ; He, L (He, Le)^[ 5 ]; Zhang, XH (Zhang, Xiaohong)^[ 5 ] ; Yuan, JY (Yuan, Jiayin)^[ 10 ] ; Wu, T (Wu, Tom)^[ 11 ] ; Ozin, GA (Ozin, Geoffrey A.)^[ 2,3,4 ] 

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 2018, 57(38): 12360-12364

DOI: 10.1002/anie.201805514

 WOS:000444225100024

Abstract

Ammonia, a key precursor for fertilizer production, convenient hydrogen carrier, and emerging clean fuel, plays a pivotal role in sustaining life on Earth. Currently, the main route for NH3 synthesis is by the heterogeneous catalytic Haber-Bosch process (N-2+ 3H(2) -> 2NH(3)), which proceeds under extreme conditions of temperature and pressure with a very large carbon footprint. Herein we report that a pristine nitrogen-doped nanoporous graphitic carbon membrane (NCM) can electrochemically convert N-2 into NH3 in an acidic aqueous solution under ambient conditions. The Faradaic efficiency and rate of production of NH3 on the NCM electrode reach 5.2% and 0.08 gm(-2) h(-1), respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22% and 0.36 gm(-2) h(-1), respectively. As this system offers the potential to be scaled to industrial levels it is highly likely that it might displace the century-old Haber-Bosch process.