Science Daily March 7, 2022
Scientists have long tried to use graphene as a sieve. However, it doesn’t have any pores. An international team of researchers (Germany, USA – Yale University) found that bilayer silica composed of corner-sharing (SiO4) units to be permeable for small molecules due to its intrinsic lattice openings. Their study sheds light on the mass transport properties of freestanding 2D SiO2 upon using atomic layer deposition (ALD) to grow large-area films on Au/mica substrates followed by transfer onto Si3N4 windows. Permeation experiments with gaseous and vaporous substances revealed the suspended material to be porous, but the membrane selectivity appears to diverge from the size exclusion principle. Whereas the passage of inert gas molecules is hindered, condensable species like water are found to cross vitreous bilayer silica a thousand times faster in accordance with their superficial affinity. This work paves the way for bilayer oxides to be addressed as inherent 2D membranes. Their results may be of high relevance to the materials science community…read more. TECHNICAL ARTICLE
Graphical abstract. Credit: Nano Lett. 2022, 22, 3, 1287–1293, January 19, 2022