| Graphene,as a new kind of two-dimensional carbon material,has attracted academic and industrial attention since it was successfully stripped by the two professors Andre Geim and Novoselov at Manchester University in 2004 and won the 2010 Nobel Prize in Physics.Due to its unique structure and excellent physical and chemical properties,graphene is considered as the first choices for research across a broad spectrum of application such as photoelectric materials,energy storage materials,nanoelectronic devices,multifunctional composites and biomedicine,etc.However,mass production of high-quality graphene sheets to meet the demand for the industrialized applications is still facing great challenge.Therefore,it is urgent to study a simple,cost-effective and eco-friendly method of mass production of high-quality graphene.To address this problem,this paper aims to proposed a novel and facile route to prepared graphene and its functional application made the following columns:?1?We propose a simple,effective method to prepare graphene aggregates?GAs?in which the intercalation and expansion of graphite are realized by only one step under ambient conditions,not involving any heating or any sophisticated devices.The results showed,GAs prepared by such an room-temperature and little-acid method exhibits a expansion volume of up to 225 times.Most importantly,the used amount of concentrated H2SO4,which acts as the intercalant,can be dramatically decreased by about 85%in comparison to that used in the conventional methods.The binary-component system comprised of?NH4?2S2O8 and concentrated H2SO4 is used for the GAs preparation,parts of?NH4?2S2O8 acts as the oxidant to oxidize the graphite edge,enabling H2SO4 to intercalate into the gallery of graphite interlayers.At the same time,parts of the excess?NH4?2S2O8 may be dragged into the gallery by H2SO4during its intercalation.Due to its chemical instability,the intercalated persulfate may decompose and release O2 gas to cause the instantaneous pressure rise within the graphite interlayer gallery,thereby engendering the expansion of GICs,and finally forms worm-like GAs.?2?A novel binary-component system made by a combination of SPC and concentrated H2SO4 for the exfoliation of graphite,where SPC is first used as the exfoliating agent.The exfoliation of graphite includes only one step,which is realized by simply mixing the graphite in the SPC and H2SO4 binary-component system and then standing for 4 h at room temperature,not involving any sophisticated devices.The results showed that the resultant graphene possesses a large average sheet area of276.8?m2and few structure defects with a low oxygen content of 1.65%,suggesting its large-size and high-quality feature,which is also evidenced by the excellent electrical conductivity of 1.90×105 S m-1.The mechanism was also deduced that the O-O bond not only makes the SPC possesses strong oxidation but also results its unstable structure.When the used amount of the SPC is excess,the concentrated H2SO4 will drag it into the gallery of graphite interlayers together during the intercalation,and further leading to the rupture of the O-O bond and the evolution of gas.Therefore,the graphite layers was exfoliated into graphene under the gas overcome the Van der Waals forces.?3?We propose a novel and facile synthesis approach of porouscarbon/graphene composite.Graphene is obtained from the GAs,not involving the use of graphite oxide?GO?.In addition,porous carbon is acquired by carbonization and KOH-activation of polyrvinylpyrrolidone?PVP?,which is used to exfoliate GAs into graphene and inhibit the restacking of the resultant graphene in the present work.The results demonstrated that The prepared porous carbon/graphene composite behaves a high SSA(3008 m2 g-1)and a hierarchical micro-and meso-pore structure?dominant pores in the range of 1-5 nm?.Electrochemical measurements demonstrate that the as-prepared porous carbon/graphene composite can deliver an outstanding specific capacitance of up to 340 F g-11 at 5 mV s-11 in 6 M KOH electrolyte.Moreover,the prepared porous carbon/graphene composite as the electrode material also exhibits excellent cycling stability?94.4%capacitance retention over 10000 cycles?.The as-fabricated symmetrical supercapacitor exhibits a high energy density of 10.9 W h kg-1?based on total mass of electrode materials?and an outstanding energy density retention even at high power density. |
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