A critical review of the state-of-the-art green ammonia production technologies- mechanism, advancement, challenges, and future potential

Ammonia is significant in various industrial and transportation applications: carbon-free fuel, synthetic fertilizers, mining, medicines, water treatment, polymers, and textiles. In recent times, the utilization of green ammonia as an environmentally sustainable fuel with zero carbon emissions has garnered significant attention. Electrocatalysis, photocatalysis, photoelectrocatalysis, and biocatalysis are the most common catalytic methods in ammonia production. However, a substantial financial investment, lengthy time frame, eco-friendliness, energy-intensiveness, and ammonia yield need to be considered, during long-term application within the ammonia economy. Therefore, this review delivers insights into the comprehensive examination of existing scholarly literature on ammonia characteristics and different methods of ammonia production. Specifically, principle, strategies, reaction mechanism, catalysts engineering, and state-of-the-art photocatalysis, photoelectrocatalysis, electrocatalysis, and biocatalysis methods in ammonia production has been extensively articulated in this review. The challenges and advantages of each green ammonia production method have been highlighted. In the photocatalytic ammonia synthesis, comprehensive analysis and discussion of bismuth-based materials, Noble metalmodified photocatalysts, Metal-free semiconductor photocatalysts, and Metal sulphide-based materials were undertaken to lay a podium for green ammonia as promising material for various applications.