POROUS CARBON NANOMEMBRANES: TWO-DIMENSIONAL MATERIALS FOR SEPARATION TECHNOLOGY

by Armin Gölzhäuser

Friday Jul 18, 2025, 3:00 PM → 4:00 PM Europe/Berlin

H6 (UHG)

Clean water is a global challenge, and membrane filtration is a key technology to achieve it. There are growing research efforts to explore the use of two-dimensional carbon materials as nanoconduits for transport and separation. Here, we report on the fabrication and application of carbon nanomembranes (CNMs). CNMs are two-dimensional membranes with a thickness of ~1 nm made by electron-induced cross-linking of self-assembled monolayers. CNMs made from terphenylthiol (TPT) molecules possess sub-nm pores of a density of ~10¹⁸ m⁻², which corresponds to one sub-nm channel per square nanometer. TPT CNMs let water molecules rapidly pass through, while they efficiently hinder the translocation of other molecules and ions. TPT CNMs have been utilized as forward osmosis membranes. Their membrane resistance reaches ~10⁴ Ω·cm² in 1 M Cl⁻ solutions, comparable to lipid bilayers. To investigate molecular transport through the tortuous sub-nm pores of CNMs, we studied the permeation of gases and vapors of different sizes (D₂O, He, N₂, O₂, CO₂, CHCl₃, C₇H₈ und C₆H₁₄), as well as of mixtures of water with the above molecules. In all mixtures the water permeation was much higher than the permeation of the other molecules, resulting in a high selectivity of the CNM. To explain this behavior, models of adsorption-controlled permeation (ACP), and water-assisted permeation are introduced.