Contact Electrification via Redox-Active Molecules.

Area of Science:

• Materials Science
• Surface Chemistry
• Energy Harvesting

Background:

• Contact electrification involves charge transfer between materials, influenced by surface chemistry.
• Efficient charge separation is crucial for harvesting electrical energy from mechanical energy.

Purpose of the Study:

• To explore electronic charge transfer in contact electrification using surface functionalization.
• To develop a method for quantifying charge transfer at the micrometer scale.

Main Methods:

• Functionalization of Au(111) surfaces with redox-active organic molecules (donors and acceptors).
• Characterization using X-ray photoelectron spectroscopy, electrochemical methods, and density functional theory.
• Development of a contact electrification assay combining atomic force microscopy and Kelvin probe force microscopy.

Main Results:

• Stable, covalent immobilization of redox-active molecules was achieved.
• A precise measurement of charge transfer between functionalized surfaces was enabled.
• An electron-driven mechanism yielding surface charge densities of (120 ± 17) µC m⁻² was revealed.

Conclusions:

• Electron transfer can be the origin of contact electrification, depending on material choice.
• The findings deepen the understanding of contact electrification mechanisms.
• This work paves the way for developing more efficient triboelectric devices.