Cyclodextrin inhibits zinc corrosion by destabilizing point defect formation in the oxide layer

Area of Science:

• Materials Science
• Electrochemistry
• Surface Chemistry

Background:

• Corrosion inhibitors reduce metallic material corrosion by adsorbing onto the metal surface.
• Understanding the molecular mechanisms of inhibition is crucial for developing effective strategies.

Purpose of the Study:

• To investigate the corrosion inhibition of zinc in chloride solution using beta-cyclodextrin (β-CD).
• To elucidate the adsorption mechanism and electronic properties of the β-CD/ZnO interface.

Main Methods:

• Electrochemical impedance spectroscopy (EIS) to measure inhibition efficiency.
• Raman spectroscopy to confirm β-CD adsorption.
• Angular dependent X-ray photoelectron spectroscopy (ADXPS) and ultraviolet photoelectron spectroscopy (UPS) to determine interface electronic structure.

Main Results:

• β-CD achieved up to 85% inhibition efficiency for zinc corrosion.
• A monomolecular layer of intact β-CD was adsorbed on the zinc oxide surface.
• A significant energy level shift at the β-CD/ZnO interface was observed, similar to an n-p junction, blocking electron transfer.

Conclusions:

• β-CD acts as an effective corrosion inhibitor for zinc by altering the defect chemistry of the protective ZnO layer.
• Modulating the defect chemistry of passivating films via molecular inhibitors is a promising approach for corrosion control.