Title: Molecular contributions to thermo-osmotic phenomena for an electrolyte at a charged surface

Abstract: Thermo-osmotic flows - generated at liquid-solid interfaces by thermal gradients - can be used to produce electric currents from waste heat on charged surfaces. The two key parameters controlling the current are the surface charge and the interfacial enthalpy excess due to liquid-solid interactions. While it has been shown that the contribution from water to the enthalpy excess can be critical, how this contribution is affected by surface charge remained to be understood. Here we use molecular dynamics simulations to investigate the impact of surface charge density on the interfacial enthalpy excess, for different distributions of the surface charge, and two different wetting conditions. We observe that surface charge has a strong impact on enthalpy excess, and that the dependence of enthalpy excess on surface charge depends largely on the surface charge distribution. In contrast, wetting has a very small impact on the charge-enthalpy coupling. We rationalize the results with simple analytical models, which can be used as guidelines to search for systems providing optimal waste heat recovery performance.