Advancements in MBenes: synthesis, Surface chemistry, and photocatalytic application in water pollutants degradation

Abstract Two-dimensional transition metal borides, known as MBenes, have recently gained significant attention due to their unique layered structure, metallic conductivity, tunable surface terminations, and promising optical properties. This review provides a consolidated overview of their synthesis pathways, emphasizing the transition from MAB phases to 2D MBenes through chemical etching, molten-salt strategies, and emerging fluorine-free routes. The influence of synthesis conditions on phase purity, structural integrity, and surface chemistry is discussed. In addition, the physicochemical, mechanical, electrical, and optical properties of MBenes are systematically summarized, highlighting how bonding characteristics, layer thickness, and termination groups dictate stability, charge transport, and interlayer adhesion energies. Particular attention is given to structure–property relationships that define their behavior under catalytic and aqueous environments. The dual functionality of MBenes in water purification is examined through their strong adsorption ability and photocatalytic reactivity, both governed by surface states, defect engineering, hybridization, and charge-transfer pathways. The review also identifies key limitations such as oxidation sensitivity, scalability challenges, and uncertainties regarding long-term environmental compatibility that currently hinder practical deployment. Finally, emerging opportunities, including heterostructure design, doping strategies, and improved synthesis control, are outlined as promising directions for advancing MBenes toward efficient and sustainable wastewater treatment applications.