Recent advances in MXene-based nanocomposites for photocatalytic wastewater treatment, carbon dioxide reduction, and hydrogen production: a comprehensive review

This review critically examines recent advancements in MXene-based nanocomposites and their roles in photocatalytic applications for environmental remediation and renewable energy. MXenes, two-dimensional transition metal carbides, nitrides, and carbonitrides (M n+1 X n T x , where M = transition metal, X = C/N, T x = surface terminations such as O, OH, F), exhibit high electrical conductivity, tunable band structures, hydrophilic surfaces, and large specific surface areas. These properties make them highly effective in enhancing photocatalytic activity when incorporated into composite systems. The review summarizes synthesis methods, structural modifications, and the mechanisms underlying photocatalytic performance, highlighting their efficiency in degrading organic, inorganic, and microbial pollutants, converting CO₂ into value-added chemicals, and generating H₂ via water splitting. Key challenges, including stability, oxidation, and scalability are analyzed, along with strategies such as surface passivation, heterojunction formation, and hybridization with antioxidant materials to improve performance. Future research should focus on developing green synthesis methods, improving long-term stability, and exploring scalable production to facilitate practical deployment. These insights provide a comprehensive understanding of MXene nanocomposites, supporting their advancement as multifunctional photocatalysts for a clean and sustainable energy future. • Comprehensive review of MXenes and their role in photocatalytic nanocomposites. • Applications in pollutant degradation, CO₂ reduction, and hydrogen production. • Strategies for synthesis and modification to enhance photocatalytic efficiency. • Mechanistic insights: charge separation, light absorption, and surface reactions. • Discussion of stability, scalability, cost challenges, and future directions.