Giant thermoelectric response of nanofluidic systems driven by water excess enthalpy

TL;DR

This study reveals that nanofluidic systems can exhibit a giant thermoelectric response driven by water excess enthalpy, surpassing standard models and offering potential for efficient waste heat recycling.

Contribution

The paper demonstrates, through molecular dynamics simulations, that water excess enthalpy significantly enhances thermoelectric response in nanofluidic systems, providing new insights for device optimization.

Findings

Thermoelectric response is two orders of magnitude larger than standard predictions.

Water excess enthalpy and electroosmotic mobility are key factors in response enhancement.

Surface hydrodynamic slip can further boost thermoelectric performance.

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.