Ammonia synthesis by nonthermal plasma catalysis: a review on recent research progress

Abstract Ammonia is one of the most important industrial chemicals which is commonly used for producing fertilizers and cleaning solutions, as the refrigerant gas, and as the precursors for making various chemicals. With the goal of sustainable development, ammonia is also proposed as the clean fuel for decarbonized transportation. The current the Haber–Bosch process for ammonia synthesis has large footprint and operates under harsh conditions using fossil fuels as the feedstock, being recognized as the major carbon emission source. Accordingly, call for sustainable production of green ammonia using renewable energies is proposed. Ammonia synthesis assisted by nonthermal plasmas has emerged in recent years as a novel and mild electrified technology, which can potentially be coupled with intermittent renewable energies and green hydrogen. Although being promising, significant development is still needed to advance the technology towards practical applications at scales. Hence, this review comments the progression of key aspects of the plasma-assisted ammonia synthesis such as catalyst and reactor design, mechanistic understanding, and process parameters. The snapshot of the current developments and proposed perspectives hope to provide guidance for the future research efforts to drive the technology towards higher technology readiness levels.