▎ 摘　　要

For graphene oxide (GO) membranes, the repulsive forces between the carboxyl groups on GO nanosheets usually lead to an oversized interlayer height and thus low performance for precise molecular separation such as gas separation. Introducing new covalent bonding into the GO interlayer channels is an efficient approach to tune the channel height for improved size discrimination property. Herein, for the first time, we incorporated a small molecule, cysteamine with amino and thiol, into GO interlayer to react with oxygen-containing groups, narrowing the interlayer height for efficient gas sieving. The as-prepared ultrathin (similar to 50 nm) GO membranes exhibited good gas separation performance with H-2 permeance of 51.5 GPU, and H-2/CO2 selectivity of 21.3 which was higher than twice that of pristine GO. The membrane maintained its structural stability during continuous mixed gas test. In addition, another small molecule with similar molecular structure, L-cysteine, was employed to replace cysteamine to explore the universality of the crosslinking method.