Electrochemical ammonia synthesis: Mechanistic understanding and catalyst design

Summary

NH₃ production is dependent on the century-old Haber-Bosch process, which is energy and capital intensive and relies on H₂ from steam reforming, hence, contributing to greenhouse gas emissions. Electrochemical NH₃ synthesis can be realized by reaction of N₂ and a proton source under mild conditions powered by renewable electricity, which offers a promising carbon-neutral and sustainable strategy. However, N₂ has remarkable thermodynamic stability and requires high energy to be activated. Implementation of this “clean” NH₃ synthesis route therefore still requires significant enhancement in energy efficiency, conversion rate, and durability, which is only achievable through the design of efficient electrocatalysts. This article provides a timely theoretical and experimental overview of recent advances in the electrocatalytic conversion of N₂ to NH₃ underlining the development of novel electrocatalysts. Advances of in situ and operando studies for mechanistic understanding of the reaction and the main challenges and strategies for improving electrocatalytic N₂ reduction are highlighted.