The role of applied potential on particle sizing precision in single-entity blocking electrochemistry

Area of Science:

• Electrochemistry
• Nanoparticle characterization
• Surface science

Background:

• Blocking electrochemistry is a single-entity technique for sizing redox-inactive particles.
• Particle adsorption on microelectrodes causes current drops, proportional to particle size.
• Edge effects from inhomogeneous diffusion limit precision in current sizing methods.

Purpose of the Study:

• To investigate edge effect mitigation in blocking electrochemistry.
• To enhance the analytical precision of single-entity particle sizing.
• To demonstrate a generalizable method for improving blocking electrochemistry accuracy.

Main Methods:

• Computational simulations of redox species diffusion.
• Experimental electrochemical measurements at varying overpotentials.
• Analysis of current drops caused by particle adsorption on microelectrodes.

Main Results:

• Lowering overpotential mitigates inhomogeneous diffusional edge flux.
• Operating in a kinetically-controlled regime significantly reduces edge effects.
• Improved precision in particle sizing was observed for both spherical and cubic particles.

Conclusions:

• Reduced overpotential is a simple and effective method for edge effect mitigation.
• This approach enhances the precision of blocking electrochemistry for particle sizing.
• The methodology is broadly applicable to different particle geometries and types.