Designing highly selective and stable water transport channel through graphene oxide membranes functionalized with polyhedral oligomeric silsesquioxane for ethanol dehydration

Abstract Graphene oxide (GO) has opened a new era of membranes and shown exciting separation properties for molecules and ions. However, in terms of precise aqueous separations such as water/ethanol, how to enhance flux when designing GO membranes with high structural robustness and separation accuracy remains a pendent challenge. Herein, we report a facile and tunable way to tackle this issue via incorporating a kind of multifunctional polyhedral oligomeric silsesquioxane (POSS). After optimization of assembly process, the GO channels with low transport resistance, high separation accuracy and robust framework can be constructed, which arise from the rigid molecular-size siloxane cage, the hydrophilic-hydrophobic hybrid structure, and the affluent covalent cross-linking sites on POSS, respectively. As a result, the membrane achieves exceptionally high separation performance with a flux of 3.16 kg/m2 h and water/ethanol separation factor of 1303, which are 50 % and 31-fold higher than pristine GO membrane, and exhibits outstanding structural robustness in harsh operating conditions, such as high temperature, ultrahigh water concentration, acid/alkali environment and long-term operation. The strategy proposed here holds great potential to produce high-efficiency two-dimensional-material membranes for precise aqueous separations.