Activated Lone-Pair Electrons Lead to Low Lattice Thermal Conductivity: A Case Study of Boron Arsenide

Reducing thermal conductivity (κ) is an ecient way to boost the thermoelectric performance. In this paper, we propose an effective approach for realizing low κ by making the lone-pair electrons stereochemically active through bond nanodesigning. As a case study, by cutting at the (111) cross section of the three-dimensional (3D) cubic boron arsenide (c-BAs), the κ is lowered by more than one order of magnitude in the resultant two-dimensional (2D) system of graphene-like BAs (g-BAs) due to the stereochemically actived lone-pair electrons. The underlying mechanism is analyzed based on the comparative study on the thermal transport properties of g-BAs, c-BAs, graphene, and diamond. The lone-pair electrons could be the indicator of lowering κ through bond nanodesigning to change the coordination environment. The proposed approach for realizing low κ and the underlying mechanism uncovered in this study would largely benefit the design of novelmaterials for energy applications.