Ambient Electrosynthesis of Ammonia: Electrode Porosity and Composition Engineering

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 (N₂ +3 H₂ →2 NH₃ ), 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 N₂ 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 g m^-2 h^-1 , respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22 % and 0.36 g m^-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.