Giant thermoelectric response of nanofluidic systems driven by water excess enthalpy

Abstract

Nanofluidic systems could in principle be used to produce electricity from waste heat, but current theoretical descriptions predict a rather poor performance as compared to thermoelectric solid materials. Here we investigate the thermoelectric response of NaCl and NaI solutions confined between charged walls, using molecular dynamics simulations. We compute a giant thermoelectric response, two orders of magnitude larger than the predictions of standard models. We show that water excess enthalpy -- neglected in the standard picture -- plays a dominant role in combination with the electroosmotic mobility of the liquid-solid interface. Accordingly, the thermoelectric response can be boosted using surfaces with large hydrodynamic slip. Overall, the heat harvesting performance of the model systems considered here is comparable to that of the best thermoelectric materials, and the fundamental insight provided by molecular dynamics suggests guidelines to further optimize the performance, opening the way to recycle waste heat using nanofluidic devices.

arXiv commentaccepted in Physical Review Letters

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Cited by in corpus (7)

• Liquid-solid slip on charged walls: dramatic impact of charge distribution
• Fast and Versatile Thermo-osmotic Flows with a Pinch of Salt
• Sampling mobility profiles of confined fluids with equilibrium molecular dynamics simulations
• Complex coupling between surface charge and thermo-osmotic phenomena
• Electrical Response of Nanofluidic Systems Subjected to Viscosity Gradients
• Fast Increase of Nanofluidic Slip in Supercooled Water: the Key Role of Dynamics
• Electrical Conductivity of Nanoscale Hydrophobic Porous Media: Surface Charge Density and Heterogeneous Pore Structure