Thermo-osmotic and related thermophoretic phenomena can be found in many situations from biology to colloid science, but the underlying molecular mechanisms remain largely unexplored. Using molecular dynamics simulations, we measure the thermo-osmosis coefficient by both mechanocaloric and thermo-osmotic routes, for different solid-liquid interfacial energies. The simulations reveal, in particular, the crucial role of nanoscale interfacial hydrodynamics. For nonwetting surfaces, thermo-osmotic transport is largely amplified by hydrodynamic slip at the interface. For wetting surfaces, the position of the hydrodynamic shear plane plays a key role in determining the amplitude and sign of the thermo-osmosis coefficient. Finally, we measure a giant thermo-osmotic response of the water-graphene interface, which we relate to the very low interfacial friction displayed by this system. These results open new perspectives for the design of efficient functional interfaces for, e.g., waste-heat harvesting.

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什么控制热渗透？分子模拟显示界面流体动力学的关键作用

从生物学到胶体科学，在许多情况下都可以发现热渗透现象和相关的热泳现象，但是其潜在的分子机制在很大程度上尚待探索。使用分子动力学模拟，我们针对不同的固液界面能，通过机械热途径和热渗透途径来测量热渗透系数。模拟特别揭示了纳米级界面流体动力学的关键作用。对于不润湿的表面，界面处的流体动力滑移会大大放大热渗透传输。对于润湿表面，流体动力剪切平面的位置在确定热渗透系数的幅度和符号方面起着关键作用。最后，我们测量了水-石墨烯界面的巨大热渗透响应，这与该系统显示的非常低的界面摩擦有关。这些结果为设计高效的功能接口（例如废热收集）开辟了新的前景。