Anomalous proton conduction behavior across a nanoporous two-dimensional conjugated aromatic polymer membrane

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Nanoporous two-dimensional conjugated aromatic polymers (2D-CAPs) are emerging materials with potential applications in separation and energy storage.
• Understanding proton transport through these membranes is crucial for their effective utilization in electrochemical devices.

Purpose of the Study:

• To investigate the aqueous proton penetration behavior across a novel 2D-CAP membrane.
• To elucidate the factors governing proton conduction in nanoporous 2D materials.

Main Methods:

• Extensive ReaxFF reactive molecular dynamics simulations were employed.
• Analysis focused on energy barriers, nanopore structure, and hydrogen bonding interactions.

Main Results:

• The proton penetration energy barrier across 2D-CAP was found to be significantly higher than that of graphtetrayne, despite a larger pore size.
• Anomalously high proton conduction barriers are attributed to the unique atomic nanopore structure of 2D-CAP.
• Hydrogen atoms at the nanopore periphery form stable hydrogen bond networks with water molecules, reducing water mobility and impeding proton transport.

Conclusions:

• Proton penetration through nanoporous 2D materials is influenced by both pore size and the nature of atoms/functional groups at pore edges.
• The formation of stable local hydrogen bond networks by peripheral hydrogen atoms can significantly hamper proton conductivity.
• These findings offer insights into designing advanced nanoporous materials for selective proton transport.