▎ 摘　　要

Large size reduced graphene oxide (RGO) tends to restack or form irreversible agglomerates during the conventional drying. In this work, a facile and efficient drying method, involving freezing-thawing-drying approach, is developed to prepare porous RGO. The RGO exhibits a large pore volume (0.414 cm(3)/g) and specific surface area (294.9 m(2)/g). The RGO can be easily ground using mortar and pestle and be dispersed in solvent by ultrasonication. The RGO shows porous nanostructure and poorly-stacked layered structure. Compared with the RGO dried by conventional method, the RGO dried by this modified process possesses similar structural defect density. The ice crystal formed by liquid nitrogen is expected to prevent the restacking of graphene nanosheets and be beneficial to obtain porous structure. (C) 2015 Elsevier B.V. All rights reserved.