Nanoscale architecture of graphene oxide membranes for improving dehumidification performance

Thin composite graphene oxide (GO) membranes prepared from the mixture of GO nanoflakes and nanoribbons are proposed to enhance membrane stability at elevated pressure gradients. It is shown that addition of 5–15 % of GO nanoribbons to medium flake graphene oxide during deposition allows up to a 60 % increase in the porosity of GO membranes. The membranes illustrate strong barrier properties to permanent gases with a permeance below 0.01 m$^3$/(m$^2\cdot$bar$\cdot$h), while revealing high permeance to water vapor over 50 m$^3$/(m$^2\cdot$bar$\cdot$h). This results in H$_2$O/N$_2$ selectivity up to 12500 at water vapor fluxes over 1 m$^3$/(m$^2\cdot$h) at relative humidity of feed stream of 90 %. Despite $\sim$ 10 % loss of membrane performance with addition of nanoribbons, the membranes reveal an improved stability to pressure gradients. Irreversible permeance loss of composite membranes does not exceed 10 % as compared to $\sim$ 35 % performance loss for pure medium flake graphene oxide (MFGO) after long term exposure to 0.1 MPa pressure difference. An improved stability is invoked for the prevention of the irreversible conglomeration of GO flakes and appearance of permanent channels for water transport along the edges of nanoribbons.