Study Of Carbon/Si-MCPs Composite Supercapacitor And Its Field Emission

Recently,carbon materials have become popular topics in energy storage,catalysts,solar cell and field emission device,especially,in supercapacitor and field emission device.The use of thicker electrode,which is composed of 3D orderly carbon-based composites,strongly facilitate the development ofthe concept of volume energy density of supercapacitor and current density of field emission device.Herein,we produced 3D macroporous electrically conductive network(MECN)by the method of photon-assisted electrochemical etching of silicon followed by electroless nickel deposition process.Moreover,carbon-based composites/MECN electrode is synthesized and applied in supercapacitor and field emission devices.First of all,the MECN are fabricated by the way of MEMS process,photo-assisted electrochemical etching and liquid flow electroless nickel plating.MECN with order construct,high aspect ratio and high specific area as the 3D templates are the square array with channels about 250 ?m in deep and 5 ?m×5 ?m in square size,and the thickness of the wall is about 1 ?m,and an intrinsic resistance is on the order of k?.Then,carbon microsphere are deposited on the surface and channel wall of MECN via the hydrothermal route to fabricated 3D porous carbon microsphere electrode.Moreover,the MnO2/C/MECN electrode is produced by the carbon-assisted reaction,and the materials are verified to be good electrode for supurecapacitor with high specific capacitance(497 F/g)at 1 A/g.The MnO2/C/MECN||AC/Ni-foam hybrid supercapacitor(Lithium-Ion Hybrid Supercapacitors,LIHSs)show a high volume energy density of 0.50 mW h/cm3,and 55.5 Wh/kg at a power density of 4k W/kg.A blue LED can be driven by three cells in series for 100 minutes.The above results illustrates that 3D orderly porous carbon microsphere electrode have large potential in application in supercapacitor.Moreover,To improve the stability of graphene-based device,the key is to restrain aggregation of graphene.So,herein,the multilayer nanographene are formatted on the surface and channel wall of MECN(MLG-MCPs)by solvothermal carbonization and post-annealing method.The characteristics of the samples are checked by the XRD,Raman,TEM and electrochemical measurement,indicating the MLG with50-100 nm length,which are rippled and wrinkled,high crystallinity and electrochemical steability.In addition,to develop the volume energy density for carbon-based composites supercapacitor,3D homo-nanostructured MnO2/nanographene/MECN electrode are synthesize by the method of a carbon-assisted reaction(C and KMnO4)and a redox reaction(MnSO4 and KMnO4)on the as-prepared MLG-MCPs astemplate to deposite 8-MnO2 and ?-MnO2.The thinner 8-MnO2is to increase the adhension to substrate,then the thicker ?-MnO2 can improve the specific capacitance.The materials are assessed as an electrode with a specific capacitance of 4.5 F/cm2 as well as excellent cycle stability(83%after 20000 cycles in 1 M Na2SO4).The homo-nanostructured MnO2/nanographene/MECN||AC/Ni-foam hybrid supercapacitor(Lithium-Ion Hybrid Supercapacitors,LIHSs)shows an volume energy density of 1.0 mW h/cm3,and 40.3 Wh/kg at a power density of 1k W/kg.The 45 parallel red LEDs can be drived by four cells in series for 10 minutes.The above results illustrates that the construct and loading mass of 3D homo-nanostructured MnO2/nanographene membrane on orderly porous thicker electrode can be controlled and result in a high volume energy density and cycle stability.Furthermore,the stability and current density of field emission device are crucial for application.In this work,the MLG-MCPs as framework,the effect of annealing and N-doping on performance of electron field emission are explored.The materials are characterized by SEM?XPS?XRD etc.The field emission properties of the samples are also tested.The turn-on field of the sample annealed at high annealing temperature has been reduced to 2.0 V/?m and reached to only 0.5V/?m under NH3 plasmas treatment.We found that the defect density will increase under high temperature annealing,which will facilitate to improve the field emission characteristic.After N-doping,the surface electron density of states,defect density and sharp edge could be dramatically increased,reducing surface work function to develop the field emission characteristic.Finally,compared to carbon-based composited on MECN,the effects of hollow Mo S2 nanomaterials on supercapacitance performance are studied.We report a simple hydrothermal technique followed by annealing to fabricate hollow nanostructured MoS2,flower-like,and nanosheets structure via CTAB as a surfactant,and then the electrochemical performance are also studied by us.The results show that the hollow MoS2 nanomaterials on Ni-foam have a promising application in supercapacitor,which is consist with carbon-based composites on MECN.