Emerging frontiers of MXenes: structure, properties and energy applications

Abstract Since their discovery in 2011, MXenes have emerged as a rapidly growing class of two-dimensional materials with exceptional properties. In view of the expanding body of theoretical and experimental research, this review presents a concise and integrated overview of MXenes, covering their fundamental properties, synthesis strategies, and emerging applications. MXenes exhibit high mechanical strength and flexibility, while electronic properties ranging from metallic to semiconducting depending on surface terminations. In addition, their optical and magnetic features enable applications in optoelectronics, photocatalysis, spintronics, and data storage. Strategies for tuning MXene properties, including defect engineering, elemental doping, strain modulation, and hybrid formation, are also discussed. MXenes are primarily synthesized from layered MAX phases via selective etching, whereas alternative approaches such as fluoride salt etching, alkali treatment, molten salts, and bottom-up methods have also been developed to tailor their surface chemistry and properties. Furthermore, recent advances in energy-related applications, particularly hydrogen evolution reaction catalysis and electrochemical energy storage in batteries and supercapacitors, are highlighted. By integrating density functional theory insights with experimental progress, this review outlines key design principles and future directions for MXene-based functional materials.