Controllable Preparation Of Nano-graphene Oxide And Its Applications In Chemical Separation And Energy Storage

Graphene shows great application prospect in sensor,semiconductor,biomedicine,new display,energy storage and conversion,mass separation and purification owing to its high specific surface area,high mechanical strength,high electron mobility,high light transmittance and unique two-dimensional structures.Graphene oxide(GO),the most important derivatives of graphene,is considered to be the most important precursor of graphene and the basic building unit of graphene-based materials.Nano-GO(NGO),with a lateral size of 100 nm or less,exhibits a vital role in bioimaging,biosensing,photothermal treatment,catalysis and photovoltaic cells due to its higher solubility in water,higher specific surface area and higher chemical reactivity compared to GO.The main works in this paper focus on the controllable preparation of NGO and its applications in mass separation and energy storage.The main contents are as follows:(1)Fabrication and separation performance study of nano-graphene oxide membranes.A series of GO with different lateral size,including NGO with a lateral size of 100 nm,were synthesized via top-down method from graphite.The elemental composition of GO and the types and quantity of oxygenous groups on GO were not changed even though the size of GO decreased from micro-scale to nano-scale.However,the water solubility was greatly affected by the lateral size of GO.Vacuum filtration self-assembly technique was applied to fabricate GO membranes.The morphology and structure of GO membranes are greatly affected by the lateral size of GO.With the decrease of lateral size,the surface of GO membranes becomes smoother and more compact while the interlayer spacing of GO membranes remains unchanged.The separation performance of GO membranes was studied by sieving organic dyes from water.The permeability of GO membranes increases significantly with the decrease of lateral size of GO while the selectivity of GO membranes decreases slightly.(2)Fabrication and separation performance study of nano-graphene oxide/fullerene composite membranes.C60-NGO nanosheets possessed sandwiched structures were first fabricated through electrostatic adsorption between C60(EDA)10 and NGO.C60-NGO membranes were fabricated by vacuum filtration self-assembly technique from C60-NGO nanosheets.C60-NGO membranes possesses a laminar structure where C60(EDA)10 molecules and NGO are arranged alternately.The interlayer spacing of C60-NGO membranes is controlled precisely from 0.91 nm to 1.56 nm by the content of C60(EDA)10.The C60(EDA)10 molecules sandwiched between NGO nanosheets act not only as spacer to extend the interlayer spacing of C60-NGO membranes,but also act as crosslinker to bond the adjacent NGO nanosheets together.The C60-NGO membranes show high water permeability and excellent size selectivity when applied to water purification.(3)Preparation and capacitive performance study of three-dimensional nano-graphene.Three-dimensional graphene and three-dimensional nano-graphene were synthesized via hydrothermal method from micro-scale GO(MGO)with a lateral size of 2 ?m and NGO with a lateral size of 100 nm,respectively.Compared to three-dimensional graphene,three-dimensional nano-graphene possesses higher porosity,higher specific surface area and more pores which are favorable for charge storage.As the electrode material of supercapacitor,three-dimensional nano-graphene shows more superior energy density and power density.