Ultrafast synthesis of 3D porous flash graphene and its adsorption properties

3D hierarchical porous graphene (3D HPG) has recently captured significant attention due to its unique porosities, excellent electron transport capability, and multifunctionality. However, given that the traditional preparation method of 3D HPG is time-consuming, energy-consuming and seriously polluting, which seriously block its wide application. This study leveraged the capabilities of flash Joule heating (FJH) to ultrafast synthesize 3D porous flash graphene (3D PFG) with good dispersion and adsorption properties from bituminous coal (BC) within 21 s. The thermal shock generated by carbonate pyrolysis and the thermal expansion generated by Joule heating were used to produce the stable porous structure. Moreover, the specific surface area of 3D PFG was as high as 504 m2g−1, and displayed the characteristics of hierarchical porous structure of micropores, mesopores and macropores. The porous structure changes of 3D PFG synthesized by FJH under different carbonate ratios and different flash voltages were investigated, and the controllable synthesis conditions of hierarchical pore structures during FJH were obtained accordingly. As the experimental and simulation results show, the 3D PFG displays good dispersibility and good adsorption performance as adsorbent for methylene blue and methyl orange. This environmentally friendly synthetic process of FJH not only simplifies the preparation process of 3D HPG but also provides a valuable way for the high value-added utilization of coal.