Orbitally driven giant thermal conductance associated with abnormal strain dependence in hydrogenated graphene-like borophene

• Published in: npj computational materials 2019-04, Vol.5 (1), Article 47
• Main Authors: He, Jia, Li, Dengfeng, Ying, Yan, Feng, Chunbao, He, Junjie, Zhong, Chengyong, Zhou, Hangbo, Zhou, Ping, Zhang, Gang
• Format: Article
• Language: English
• Subjects: 639/301/357/1018; 639/925/357/1018; Boron; Borophene; Carrier density; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computational Intelligence; Conductance; Conduction; Dependence; Electron density; First principles; Graphene; Heat transfer; Hydrogen; Hydrogen atoms; Hydrogen storage; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Offsets; Phonons; Tensile strain; Theoretical; Thermal conductivity; Two dimensional materials
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-019-0183-2

Heat energy in solids is carried by phonons and electrons. However, in most two-dimensional (2D) materials, the contribution from electrons to total thermal conduction is much lower than that for phonons. In this work, through first-principles calculations combined with non-equilibrium Green’s function theory, we studied electron and phonon thermal conductance in recently synthesized 2D hydrogen boride. The hexagonal boron network with bridging hydrogen atoms is suggested to exhibit comparable lattice thermal conductance (4.07 nWK −1  nm −2 ) as graphene (4.1 nWK −1  nm −2 ), and similar electron thermal conductance (3.6 nWK −1  nm −2 ), which is almost ten times that of graphene. As a result, total thermal conductance of 2D hydrogen boride is about two-fold of graphene, being the highest value in all known 2D materials. Moreover, tensile strain along the armchair direction leads to an increase in carrier density, significantly increasing electron thermal conductance. The increase in electron thermal conductance offsets the reduction in phonon thermal conductance, contributing to an abnormal increase in thermal conductance. We demonstrate that the high electron density governs extraordinarily high thermal conductance in 2D hydrogen boride, distinctive among 2D materials.