MBenes: emerging two-dimensional metal borides for multifunctional energy storage and conversion technologies

Abstract

The increased demand for efficient and sustainable energy storage has contributed to the rising interest in investigating emerging two-dimensional (2D) materials that are derived from MAB (metal atom and boron atom) phases with a very high metal-to-boron ratio as strong potential candidates for advanced energy-based applications and technologies. These MBenes exhibit excellent electrical conductivity, mechanical stability, and a large surface area that enables performance tuning for various electrochemical applications by controlling the surface terminations. Overall, compared with other materials that are currently used for commercial energy storage, for example, batteries and supercapacitors, MBenes show superior rate capability and higher specific capacitance with better cycling durability, which makes them one of the most successful families of 2D materials studied to date. MBenes also display superior performance and mechanical flexibility when combined with advanced 2D nanomaterials such as graphene, metal oxides, and Prussian blue analogues. Beyond energy storage applications, these materials are also being considered for application in electrocatalysis, gas sensing, carbon capture, and solar-assisted water purification and fuel production. Their tunability and robust structure, alongside material diversity, provide new design pathways. Despite growing research, comprehensive discussions on the broader implications of MBenes remain limited. Most existing reviews tend to summarize applications but often overlook recent advances in synthesis strategies, intentional heterostructure design, and integrated multifunctional systems. Therefore, a critical and timely review is needed to consolidate the dispersed body of knowledge and highlight key challenges and opportunities for real-world implementation. This work aims to fill this gap by offering a detailed account of the synthesis methodologies, electrochemical performance, and structural benefits of MBenes while exploring their emerging multifunctional applications. It also outlines the existing limitations and proposes potential directions for future research to accelerate their translation into practical technologies.