Porous Graphene-based Materials:Preparation And Application

With the development of our society,portable electronic devices and automobiles have become a part of people's life.Lithium ion batteries?LIBs?are the important carrier of energy storage areas,traditional anode materials of Lithium ion battery cannot meet the needs of higher power density.Graphene has received extensive attention over the years.Porous graphene-based materials are considered to be good energy storage materials,such as supercapacitors and LIBs.In this thesis,porous graphene-based materials have been demonstrated by all kinds of technologies.The morphology,porous properties,and chemical composition of the hierarchically porous graphene-based materials have been revealed by using various characterization methods,including SEM,TEM,XPS,and nitrogen sorption measurements.Furthermore,the as prepared materials have been applied into the organic vapor adsorption,supercapacitor and LIBs.Two kinds of hierarchically porous graphene-based materials were prepared through carbon dioxide activation of graphene aerogel and nitrogen-doped graphene aerogel,respectively?denoted as pGA and pNGA?.The activation process avoids the use of corrosive activation agents,the multiple post treatment steps,and the destruction of porous structure of aerogels.Specifically,as an adsorption material,pGA with a high specific surface area(1760 m²g^–1)and large pore volume(5.5 cm³g^–1)exhibits excellent organic vapor adsorption capacity at 298 K,so far the best organic vapor adsorption performance(toluene,2860 mg g^–1;methanol,2370 mg g^–1)among all porous materials.The as-prepared pNGA displays a high specific surface area(2040 m²g^–1)and large pore volume(6.2 cm³ g^–1),demonstrating excellent electrochemical performance when used as a supercapacitor electrode.ZIF-67@NGA composite was synthesized by in situ synthesis of ZIF-67 in the nitrogen-doped graphene network,calcined in air to get porous Co₃O₄@NGN material.The synergistc effect of NGN and Co₃O₄ makes the material has excellent properties.The porous structure of NGN not only reduce the electronic transmission distance but remit the volume effect of Co₃O_4.As an anode material,specific capacity is 1030 mA h g^–11 in a current density of 100 mA g^–1,and specific capacity remains at 99%after 400 cycles in a highly current density of 1 A g^–1,showing excellent cycling stability.