Interfacial thermal conductance at the gas-solid interface: microscopic energy transport mechanisms and the thermal rectification phenomenon

The thermal conductance across gas-solid interfaces is the primary pathway for thermal dissipation in low thermal conductivity materials. However, research on energy transport at the gas-solid interface is limited, leaving the mechanisms that influence thermal properties unclear. In this study, we systematically investigate the microscopic behavior of gas on solid surfaces and decouple two distinct collision modes that influence energy transfer efficiency: immediate reflection and adsorption-reflection. Our findings reveal an intrinsic thermal rectification up to 30 % at the gas-solid interface, indicating that asymmetric energy transfer occurs. This asymmetry in energy transfer efficiency arises from variations in the proportion of the two collision behaviors. Collision frequency is a key factor influencing energy transport efficiency across gases with varying densities. Additionally, a convergence point is observed when a dense gas layer adsorbs at the solid interface, where gas interactions dominate interfacial thermal conductance. These findings offer new insights into the microscopic mechanisms of energy transport at the gas-solid interface, providing a foundation for optimizing thermal properties in insulation materials.