Selectively Expanding Graphene Oxide Paper for Creating Multifunctional Carbon Materials

Flexible, paper-based graphene and graphene oxides are now emerging as a new class of materials with a variety of applications in electrochemical devices, novel composites, antibacterial agents, separation membranes, and so on. But the tight layer and the poor permeability limit their applications in the fields requiring permeable layers and tunable layer spacing. We demonstrate that the temperature-dependent decomposition reaction of ammonium nitrate can be utilized to modulate the layer spacing of graphene oxide paper and modify its permeability. Unlike the commonly used intercalation method, our strategy enables the layer spacing of the paper to be expanded over large range (123%-20 000%) and avoids the occupation of layer room by guest molecules. Dependent on the expansion amplitude, the papers exhibit a variety of interesting applications, including the highly efficient exclusion of small organic molecules, the separation of ultrathin nanoparticles, and the loading of polar and nonpolar guest molecules. Further, owing to the recovery of the electrical conductivity, the modified papers with large permeability should be also potential materials for flexible, paper-based electrochemical devices.