Charge Regulation and pH Effects on Thermo-Osmotic Conversion

Area of Science:

• Sustainable Energy Harvesting
• Nanopore Science
• Thermoelectric Conversion

Background:

• Thermo-osmotic energy conversion utilizes waste heat for sustainable power generation.
• Current research focuses on materials to improve the Seebeck coefficient (thermoelectric voltage).
• The influence of surface charge distribution on nanopore thermo-osmotic performance remains underexplored.

Purpose of the Study:

• To numerically investigate the impact of surface charge-regulation density and KCl solution pH on the Seebeck coefficient in thermo-osmotic energy conversion.
• To analyze how pH variations affect ion transport and thermo-osmotic performance.
• To confirm the potential of pH modulation for enhancing osmotic power generation from low-grade heat.

Main Methods:

• Numerical simulation employing Nernst-Planck-Poisson, Navier-Stokes, and heat transfer equations.
• Analysis of surface charge-regulation density and pH effects on the Seebeck coefficient.
• Systematic variation of pH levels in KCl solutions to study ion transport dynamics.

Main Results:

• The highest ionic Seebeck coefficient achieved was -0.64 mV/K at 10⁻⁴ M KCl and pH 9.
• Both pH level and pore structure significantly influence thermo-osmotic performance.
• Experimental results confirm that pH can effectively enhance thermo-osmotic conversion for energy harvesting.

Conclusions:

• Surface charge distribution and solution pH are critical factors in thermo-osmotic energy conversion.
• Optimizing pH offers a viable strategy to enhance the efficiency of harvesting osmotic power from low-grade heat.
• This research provides insights into advancing sustainable energy technologies through nanopore-based systems.