| Graphene is a two-dimensional carbon nanomaterial with highly conjugated π-bond interactions.It is considered the most promising carbon-based material due to its large specific surface area,excellent charge carrier mobility,and high thermal/chemical stability.Graphene materials can be applied in various fields in daily life and industrial processes.Anthracites,the most metamorphic coal species,contain many components with aromatic carbon ring structures,which can be used to construct a graphene framework.Based on the character mentioned above,Jincheng anthracite is used as a raw material to make coal-based graphene by adjusting the organic structure of the coal component.The relative process is also developed.Furthermore,the obtained coal-based graphene is functionalized and applied in oxygen reduction reaction(ORR)for catalytic proposes.The main research results are:(1)Jincheng coal,featured with low cost and easy obtaining,is used as a carbon source.Jincheng coal is processed by pulverization,grinding,acid leaching,and deashing to produce coal-based graphite.The obtained graphite is handled by the improved Hummers method with graphitization and high-temperature pyrolyzation to produce graphene(CGO).Nitrogen-doped coal-based graphene oxide(NG)was successfully prepared by pyrolysis of coal-based graphene oxide and nitrogen-doped nanocrystalline cellulose at a high temperature.The morphology,crystal structure,defects,nitrogen-based group,and ORR activity are tested.The results show that NG has higher catalytic performance for oxygen reduction reaction than CGO catalyst in alkaline medium.Nitrogen-doped coal-based graphene oxide retains the excellent stability of CGO,and the current density can be maintained to 98.43%after 6 h.The introduction of nitrogen groups significantly improved the ORR catalytic activity of the composite,but it is still inferior to commercialized Pt/C catalysts.(2)Core-shell structure ZIF-67 claded by dopamines was physically anchored to the GO surface to obtain the coal-based graphene embellished core-shell carbon-based material with Co-N doping(Co-NDAC@CG).The morphology and structure of the Co-NDAC@CG can be studied by the results from SEM,TEM,Raman,XRD,BET,and XPS.Coal-based GO exhibits a novel interconnected porous structure in the conductive network with a reasonable porous rate.Also,Co-NDAC@CG,featured with high specific surface area(439 m2·g-1),showed high ORR activity.Co-NDAC@CG showed an excellent performance in half-wave potential and limiting current density in alkaline medium,with a value of E1/2=0.84 V and jk=4.73 mA·cm-2 respectively.Compared with commercial Pt/C material,Co-NDAC@CG is better in electrochemical stability and methanol resistance.(3)With the graphene made from anthracite as the precursor,Co-N@CNT-CG was prepared by combining carambola-shaped MOFs(ZIF-8@ZIF-67).The structure and morphology of the synthesized Co-N@CNT-CG were characterized by SEM,TEM,Raman,XRD,BET,and XPS.The obtained Co-N@CNT-CG is composed of many graphite carbons(including carbon nanotubes)and a large amount of Co and N doping,with a large surface area(637 m2·g-1)and an excellent three-dimensional structure.Co-N@CNT-CG exhibits excellent performance in terms of half-wave potential and finite current density in alkaline medium with a value of 0.85 V and 6.21 mA·cm-2,respectively.Moreover,Co-N@CNT-CG exhibits good electrochemical stability and methanol tolerance compared with commercial Pt/C materials. |
