MXene─A New Paradigm Toward Artificial Nitrogen Fixation for Sustainable Ammonia Generation: Synthesis, Properties, and Future Outlook

Ammonia is a commodity chemical that is manufactured worldwide and supports a growing population. Industrially, ammonia synthesis is dominated by the energy-intensive Haber–Bosch process, thus necessitating the development of a greener approach. Recently, two-dimensional transition-metal carbides/nitrides/carbonitrides, MXenes are emerging as optimistic prospects for the environmentally benign electro- and photocatalytic nitrogen fixation to ammonia. MXenes exhibit excellent hydrophilicity, large specific surface area, superior electrical conductivity, and abundant active sites. Their promising properties for functionalization prosper efficacious enhancement strategies such as co-catalyst loading as well as the formation of MXene-based composites and MXene-derived hybrids. In this Review, the characteristics, fabrication strategies, and applications of MXene-based materials in electrocatalytic and photocatalytic nitrogen fixation, relative to their roles and features, are systematically reviewed. Finally, the current challenges and future directions toward sustainable ammonia generation are provided. This work is expected to deliver valuable insights for the rational engineering of MXene catalysts toward a greener route of ammonia synthesis.