Anisotropic Thermal Conductivity of Exfoliated Black Phosphorus

We ascertain the anisotropic thermal conductivity of alumina passivated black phosphorus (BP), a reactive 2D nanomaterial with strong in-plane anisotropy. We measure the room temperature thermal conductivity by time-domain thermoreflectance for the three crystalline axes of exfoliated BP. The thermal conductivity along the zigzag direction (86 +/- 8 W/(mK)) is ~2.5 times higher than that of the armchair direction (34 +/- 4 W/(mK)).