Plasma-assisted ammonia synthesis utilizing water as a hydrogen source: progress, challenges, and prospects

Ammonia, a vital chemical precursor primarily used in nitrogen fertilizer production, is also a promising hydrogen carrier. However, conventional ammonia synthesis methods, notably the Haber-Bosch process, are energy-intensive and environmentally unsustainable. This review explores the emerging field of plasma-based ammonia synthesis using water as a hydrogen source, offering a greener and potentially sustainable alternative. Non-thermal plasma technology, operating under mild conditions, facilitates nitrogen fixation by activating inert nitrogen molecules through electron impact, collisions, and dissociation processes. Utilizing water instead of pure hydrogen reduces costs and enhances safety, eliminating the need for high-pressure hydrogen storage. This review summarizes prevailing plasma approaches, including dielectric barrier discharge (DBD), sliding arc, and plasma jet reactors, highlighting their impact on reaction efficiency. Critical challenges such as low ammonia selectivity and high by-product formation are discussed, emphasizing the need for advanced catalyst development and reactor optimization. Strategies like catalyst pore protection and integration with electrocatalysis and membrane technologies are proposed to enhance the synthesis efficiency. Despite showing promising results in the laboratory, scaling up plasma-based ammonia synthesis to industrial levels necessitates further research into catalyst stability, reaction mechanisms, and process economics. Future prospects include leveraging AI and high-throughput methods for catalyst design, ultimately advancing this technology towards commercial viability.