Percolative proton transport in hexagonal boron nitride membranes with edge-functionalization.

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Two-dimensional layered materials are crucial for studying water and ion dynamics.
• Hexagonal boron nitride (h-BN) is a key 2D material with potential applications in ion transport.

Purpose of the Study:

• To investigate proton transport mechanisms in functionalized h-BN membranes under hydration.
• To understand the role of edge functionalization and water content on conductivity.

Main Methods:

• Fabrication of amine-functionalized h-BN membranes.
• Hydration and water sorption measurements.
• Proton conductivity measurements at varying water loadings.
• Analysis of interlayer spacing and transport phenomena.

Main Results:

• Hydration did not alter the interlayer spacing of h-BN, indicating no water intercalation.
• Amine functionalization increased water sorption by 18-fold.
• Proton conductivity increased by 7 orders of magnitude at <5% water loading.
• Observed low percolation threshold and non-universal critical exponents suggest edge-dominated transport.

Conclusions:

• Proton transport in h-BN membranes is primarily governed by functionalized edges, not bulk intercalation.
• Edge-conduction channels enable high proton conductivity even at very low hydration levels.
• Anomalous thickness dependence of conductivity warrants further investigation into transport mechanisms.