Discovery of Bimetallic Hexagonal MBene Mo2ErB3T2.5 (T = O, F, and Cl)

Abstract Exfoliation from quaternary hexagonal MAB ( h ‐MAB) phases has been suggested as a method for producing 2D in‐plane ordered MBenes ( i ‐MBenes) with the general formula (M′ 2/3 M″ 1/3 ) 2 AB 2 . However, experimental realization of defect‐free i ‐MBenes has not been achieved yet due to the absence of a suitable parent quaternary h ‐MAB phase. In this study, a machine learning (ML) model is used to predict the stability of 15771 quaternary h ‐MAB phases generated by considering 33 transition metals for the M site and 16 p ‐block elements for the A site. Out of these compounds, only 195 are identified as potentially stable. Subsequent high‐precision first‐principles calculations confirm that 47 of them exhibit both thermodynamic and dynamic stability. Their potential for exfoliation into bimetallic i ‐MBenes is investigated by bonding analysis. Leveraging these theoretical insights, a bimetallic i ‐MBene is successfully synthesized, namely 2D Mo 2 ErB 3 T 2.5 (T = F, Cl and O). Further experimental scrutiny reveals its excellent performance for the hydrogen evolution reaction (HER), highlighting the application potential of bimetallic i ‐MBenes.