Graphene oxide-melamine nanofilm composite membrane for efficient CO2 gas separation

Technologies that absorb CO2 are essential for meeting the world’s carbon–neutral and carbon-negative goals.
When compared to the traditional adsorption/absorption processes, membrane separation is more energyefficient.
Graphene oxide (GO) membrane is one such kind of membranes that is anticipated to provide a solution
for separating CO2 gas. The repulsive forces between carboxyl groups on GO nanosheets in GO membranes
typically result in excessively high interlayer distance and poor performance for fine molecule separations such
as gas separation. The GO interlayer channels can be effectively tuned by adding new binders/crosslinkers to
enhance their size-discriminating capabilities. Here, we introduce melamine, a small molecule, for the first time
into the GO layer, where it reacts with oxygen-containing groups to enrich the amine functional group, which
aims to facilitate CO2 transport. With a CO2 permeance of 68.02 Barrer and a CO2/N2 ideal selectivity of 37.75,
which is double that of pure GO, the produced ultrathin GO-melamine membrane (~0.5 μm) demonstrated good
gas separation capability. Throughout the continuous separation tests of mixed gases, the membrane retains its
structural and performance stability.