Fig. 1: Thermally robust and reversible activated gas permeation through nanoporous graphene membranes.
From: Edge-activated graphene nanopores for thermally robust hydrogen membrane separations
a A scanning electron microscopy image and a photograph of the surface of a polyimide track-etched membrane (PITEM) supported graphene, PITEM(10)_G membrane. b A schematic showing various transport pathways involved in gas permeation through nanoporous graphene membranes including (1) bulk impingement, (2) Surface diffusion, (3) Translational diffusion, and (4) Knudsen diffusion. c–e Temperature-dependent gas permeation through bare PITEM(10) support, graphene membranes PITEM(10)_G (without pore creation), and PITEM(10)_G_Pore (with pore creation) under thermal equilibrium. Six gas species were tested in this work, namely H2, He, CH4, N2, CO2, and SF6, respectively. Markers represent experimental data. The dashed lines in (c) represent the Knudsen diffusion model prediction of permeance as a function of temperature (\(T\)), i.e., scaling with 1/\(\sqrt{T}\), given the nominal pore size and density of the PITEM(10). In (d and e), the dashed lines represent the predicted permeance of PITEM(10)_G and PITEM(10)_G_Pore, obtained by multiplying the permeance of PITEM(10) for each gas at 300 K by the average coverage and scaling it by 1/\(\sqrt T\). Error bars on the x-axis represent the standard deviation of temperature values recorded during permeance tests. The error bars on the y-axis denote the standard deviation of permeance based on error propagation (Supplementary Note 2). f Knudsen selectivity (dash line) versus selectivity calculated by the ratio of single-gas permeance over that of H2 measured at 220 °C for three PITEM(10)_G_Pore samples, prepared under the same conditions, and with sample #1 measured again after aging for over 1 year without any interim measurements during this period. \(M\) denotes molecular mass, \(J\) denotes flux, and subscripts denote the gas. The numbers at the top left of (c−e) indicate the multiplication factor (e.g., 1e-6) applied to the y-axis values. Source data are provided as a Source Data file.
