Overview of emerging catalytic materials for electrochemical green ammonia synthesis and process

The concept of "green-ammonia-zero-carbon emission" is an emerging research topic in the global community and many countries driving toward decarbonizing a diversity of applications dependent on fossil fuels. In light of this, electrochemical nitrogen reduction reaction (ENRR) received great attention at ambient conditions. The low efficiency (%) and ammonia (NH3) production rates are two major challenges in making a sustainable future. Besides, hydrogen evolution reaction is another crucial factor for realizing this NH3 synthesis to meet the large-scale commercial demand. Herein, the (i) importance of NH3 as an energy carrier for the next future, (ii) discussion with ENRR theory and the fundamental mechanism, (iii) device configuration and types of electrolytic systems for NH3 synthesis including key metrics, (iv) then moving into rising electrocatalysts for ENRR such as single-atom catalysts (SACs), MXenes, and metal-organic frameworks that were scientifically summarized, and (v) finally, the current technical contests and future perceptions are discussed. Hence, this review aims to give insightful direction and a fresh motivation toward ENRR and the development of advanced electrocatalysts in terms of cost, efficiency, and technologically large scale for the synthesis of green NH3.