Theoretical exploration of quaternary hexagonal MAB phases and two-dimensional derivatives

The newly discovered hexagonal MAB (h-MAB) phases have shown great promise in synthesizing 2-D borides, but wide application is hindered by the limited kinds of transition metals that can be involved. In this work, an extensive structure search was performed to identify stable quaternary h-MAB phases by alloying ternary h-MAB phases with a fourth component. The predicted 22 stable quaternary h-MAB phases reveal that there is plenty of room for further exploration of new materials by element alloying. Moreover, we theoretically proved the possibility of exfoliating h-MBenes from the predicted quaternary phases through the selective removal of A components. The simulations for the hydrogen evolution reaction (HER) revealed that the bi-metal combination demonstrates a great advantage to enrich the application perspectives of h-MBenes. The discovery of quaternary h-MAB phases and two-dimensional derivatives offers new insights and understanding of boride-based materials.