Electrochemical Synthesis of Ammonia from Nitrogen Under Mild Conditions: Current Status and Challenges

Abstract

The electrochemical synthesis of ammonia under mild conditions has attracted significant interest in recent years because it can allow for the direct conversion of renewable electricity to chemical energy in the form of ammonia, which is an ideal medium for energy storage and transportation. And in contradistinction to the Haber–Bosch process, the electrochemical synthesis of ammonia is a much more environmentally friendly process that can operate under mild conditions with zero carbon dioxide (CO2) emission. However, this process is severely hindered by poor ammonia formation rates and Faradaic efficiency due to the competing hydrogen evolution reaction. Based on this, a review focused on the current status and challenges of the electrochemical synthesis of ammonia is imperative to promulgate this key process and promote future research. And therefore, this review will systematically survey the recent progress of the electrochemical synthesis of ammonia; and different from previous reviews, this review will include not only advances in electrocatalysts, but also in reactors, electrolytes and reaction mechanisms. In addition, future research directions and strategies to improve the performance of ammonia electrochemical synthesis systems are proposed with the aim of shedding light on the future direction of ammonia synthesis through nitrogen electrochemical reduction.