Molten sodium-induced graphitization towards highly crystalline and hierarchical porous graphene frameworks

Mass production of high quality graphene platelets has attracted considerable interest for potential applications in various fields. Nevertheless, in literature, the graphite oxide (GO)-derived graphene is always lacking high crystallinity and hierarchical porosity. Herein, we report a new molten sodium-induced graphitization for mass-fabricating highly crystalline and porous graphene sheets. The 3D graphene hydrogels (GHs) obtained from GO by the hydrothermal self-assembly are directly annealed in molten sodium at 800 °C. As a result, the D band intensity in Raman spectroscopy is reduced significantly, while 2D band intensity is increased prominently, which is a typical characteristic of highly crystalline graphene. More importantly, the resulting Na-GFs-800 sample exhibits increased surface area and narrow mesopore size distribution (∼3.6 nm). The excellent supercapacitive performance of Na-GFs-800 has been demonstrated in an organic symmetric system. Meanwhile, the possible interaction mechanism between molten sodium and GHs has been proposed in the text. (paper)