Abstract
Energy-saving membrane separation for water purification is increasingly desired, which requires appropriate nanofiltration membranes enabling to reject undesired solutes efficiently and allows high permeation of water. Herein, we report the fabrication of three-dimensional lamellar reduced graphene oxide (rGO) hydrogel membranes with a one-step, environment-friendly and water/vapor interfacial hydrothermal assembly process and the corresponding aerogel membranes by the freeze-drying method. The structures of the aerogel membranes can be tuned from lamellar to porously interconnected morphologies by controlling the volume of GO suspensions during the hydrothermal process. The rGO aerogel membrane was extremely flexible, which can be bent in liquid nitrogen and boiling water without any deformation, and highly stable in various solvents for at least 2 months. When used as nanofiltration membranes, the rGO aerogel membranes showed ∼100% rejection of organic dyes and a moderate water flux (up to 53 L m(-2) h(-1)) only under the gravity of organic dye aqueous solutions of a 30 cm height. This water self-purification property of our flexible and stable aerogel membranes without extra energy consumption provides a possibility to make cheap, portable water purification devices for utilization in emergency and home-used water purification systems in the areas with electricity unavailable or inconvenient.