▎ 摘　　要

We report a highly efficient thermal rectification model based on the near-field thermal radiation between InSb and graphene-coated SiO2, separated by nanoscale vacuum gaps. The results show that the introduction of graphene sheet enhances significantly near-field radiative heat flux and thermal rectification efficiency owing to the strong coupling of surface plasmon-polaritons between InSb and graphene. Specifically, under the same temperature bias, a rectification efficiency exceeding 80% is obtained at vacuum gaps varying from 10 nm to 100 nm for the graphene-coated SiO2 case, while such an efficiency requires a narrower gap between 10 nm to 20 nm for the bare SiO2 case. In addition, the introduction of graphene can lower greatly the emitter's temperature T-H, e.g., an efficiency of 60% requires T-H = 550 K in the bare SiO2 case, while it requires only the temperature around 400 K in the coated SiO2 case. The above results might be helpful in designing a highly efficient thermal diode with a wider vacuum gap and a lower operating temperature. (C) 2018 Elsevier Ltd. All rights reserved.