“…Anisotropic two-dimensional (2D) layered nanomaterials have emerged in the recent years and have attracted extensive attention due to their unique atomic structures and distinguished physical properties, which intrinsically endow the orientation-dependent transport behaviors and numerous potential applications in nanodevices and nanoelectronics. − Intriguingly, anisotropic 2D nanomaterials generally possess lattice structures with very low symmetry, much different from the isotropic 2D materials, including the well-studied 6-fold graphene and transitional metal dichalcogenides . As a new degree of freedom, anisotropy in specific 2D materials, such as the orthorhombic black phosphorus (b-P, space group cmce), renders them two principal lattice axes in the basal plane, that is, the orthogonal zigzag (ZZ) and armchair (AC) directions. − Till now, many investigations have been performed to explore the anisotropic electrical, phonon vibrational, and thermal properties of 2D b-P. − For instance, the anisotropic ratio of thermal conductivity of b-P is determined to be ∼1.8 in the experiment, mainly attributed to the superior phonon velocity and scattering process along the ZZ direction …”