Graphene oxide-modified g-C3N4 nanosheet membranes for efficient hydrogen purification

Abstract Highly permeable and selective membranes are desirable for energy-efficient gas separation. Two-dimensional graphitic carbon nitride (g-C3N4) has attracted significant attention owing to its suitable pore size, high pore density, and thus minimal mass-transfer barrier. Nevertheless, it is difficult to retain the structural integrity of its two-dimensional plane during the delamination of bulky g-C3N4 into nanosheets, which has greatly hindered the preparation of high-quality g-C3N4 gas separation membranes. In this study, flexible graphene oxide (GO) nanosheets containing abundant functional groups were used to cover and remedy some defects in g-C3N4 nanosheets. Consequently, a continuous g-C3N4-GO membrane was obtained that exhibited excellent H2 permeation performance (H2 permeance: 2.16 × 10-7 mol m-2 s-1 Pa-1, H2/CO2 selectivity: 39.2) and good stability, which is promising for practical hydrogen separation processes.