Size-Sensitive Thermoelectric Properties of Electrolyte-Based Nanofluidic Systems

Area of Science:

• Nanoscale Thermoelectrics
• Computational Materials Science
• Physical Chemistry

Background:

• Thermoelectric materials convert heat energy into electrical energy.
• Nanofluidic confinement offers unique properties for energy applications.
• Graphene nanochannels provide a promising platform for studying confined fluids.

Purpose of the Study:

• To investigate the thermoelectric properties of aqueous KCl solutions in graphene nanochannels.
• To understand the influence of nanochannel height on thermoelectric performance.
• To explore the underlying mechanisms responsible for enhanced thermoelectric effects.

Main Methods:

• Molecular dynamics simulations were employed to model KCl solutions within graphene nanochannels.
• Simulations covered a range of channel heights from 0.7 nm to 7.8 nm.
• Key thermoelectric parameters, including the Seebeck coefficient and figure of merit (ZT), were calculated.

Main Results:

• Thermoelectric properties (Seebeck coefficient and ZT) showed high sensitivity to channel height (H) at small dimensions.
• A 1.0 nm nanochannel achieved a Seebeck coefficient of 30.6 mV/K and ZT of 4.6 at room temperature.
• These values surpass those of many solid-state thermoelectric materials.

Conclusions:

• Enhanced thermoelectric performance in small nanochannels is attributed to flow slip at channel walls and mean excess enthalpy density.
• The potential energy contribution significantly influences the observed thermoelectric effects.
• These findings support the application of nanofluidic devices for efficient thermal energy harvesting.