Prediction by density functional theory of auxetic behaviour in hydroxyl-terminated Mo₂B₂ MBenes

Abstract Auxetic materials exhibit unique properties, such as enhanced energy absorption and increased shear stiffness, making them beneficial for various applications. In this study, we employ first-principles calculations to investigate the structural, mechanical, and electronic properties of pristine and terminated Mo₂B₂ MBenes. Our findings reveal that some hexagonal Mo₂B₂(OH)₂ configurations present a remarkable negative Poisson’s ratio, indicating auxetic behaviour. This mechanical response is attributed to its unique bridging coordination of hydroxyl groups. The analysis of their structural and electronic properties establishes a clear correlation between termination type, bond characteristics, and the resulting mechanical properties. Our theoretical results, therefore, provide valuable insights for the design of novel 2D auxetic materials.