Preparation,Electrochemical Properties and Biosensing Applications of Several Doped Carbon Materials

Author:Deng Wen Fang

Supervisor:ma ming


Degree Year:2019





Carbon materials have abundant porous structure,large specific surface area,and excellent electrical conductivity,so they have been widely used in different fields such as energy,catalysis and sensing.The introduction of heteroatoms in carbon materials can not only improve their surface wettability,but also increase the pseudocapacitance of carbon materials,resulting in improved capacitance performance.In addition,heteroatom doping can introduce new active sites in carbon materials,so heteroatom-doped carbon materials have great application potential in the fields of catalysis and sensing.It is of great significance to prepare new heteroatom-doped carbon materials and carry out their application research.In this thesis,several new carbon materials were prepared by introducing heteroatoms such as nitrogen,sulfur,and metal into carbon materials,and their performances in supercapacitors,hydrogen evolution reaction and biosensing applications were studied.The main contents are as follows.(1)Sulfur-doped porous carbon nanosheet(S-PCNS)were prepared by direct carbonization and simultaneous chemical activation of a cobalt ion-impregnated sulfonic acid ion exchange resin.The as-prepared S-PCNS exhibits a three-dimensional interconnect structure,a high degree of graphitization,a high C/O atomic ratio(22.9:1),a high sulfur doping(9.6 wt%) and high specific surface area(2005 m2 g-1).The supercapacitor using S-PCNS as the electrode material exhibits a specific capacitance of as high as 312 F g-1 at 0.5 A g-1,excellent rate performance(78% capacitance retention at 50 A g-1),high energy density(11.0 Wh kg-1 at 0.5 A g-1) and good cycle stability(97% of initial capacitance after 10,000 cycles under 2 A g-1) in 6.0 M KOH aqueous electrolyte.(2)Nitrogen-doped three-dimensional graphene materials were prepared by using poly(o-phenylenediamine)as carbon source and nickel nitrate as graphitization catalyst precursor.The 3DNGN with interconnected porous structure and high content of nitrogen doping can ensure rapid ion transportation and fast electron transport,resulting in high electrochemical performance.The 3DNGN shows a high specific capacitance of 312 Fg-1 at 1 Ag-1 with good capacitance retention capability and good cycling stability,and outputs a high average energy power density of 10.8 W h kg-1 and a high maximum power density of 595 kW kg-1 in aqueous KOH electrolyte.Due to the great pseudocapacitance in aqueous H2SO4 electrolyte,the specific capacitance of the 3DNGN can reach a high value of 345 Fg-1 at 1 Ag-1.(3)Co-,N-and S-doped carbon(CoNS-C)prepared by heat-treating nitrogen-and sulfur-rich poly(m-aminobenzenesulfonic acid) and cobalt(II)nitrate,followed by acid etching.The overpotential of CoNS-C for hydrogen evolution reaction(HER) was 180 mV at a current density of 10 mA cm-2 in a 0.5 M H2SO4 aqueous solution.Besides the high HER activity,CoNS-C also exhibits excellent durability.The cobalt-heteroatom doped CoNS-C complex was confirmed to be a highly active molecular catalytic center of HER.This work provides a new approach to the design of highly active and durable carbonaceous electrocatalysts for HER.(4)Three-dimensional graphene carbon frameworks(3DGLCFs) were prepared by pyrolyzing polyaniline and nickel nitrate powders followed by acid etching.The as-prepared 3DGLCFs have a graphene-like network structure,high specific surface area and high content nitrogen dopant.Because these features can enable large electrochemically active surface areas,rapid electrotransfer,and fast transfer of analytes to the electrode surface,the 3DGLCFs modified glassy carbon electrode(GCE) shows current response much higher than that of commercial graphene modified GCE towards the oxidation of ascorbic acid(AA),dopamine(DA) and uric acid(UA).The anodic peak separations of 3DGLCFs/GCE is 0.23 V between AA and DA,0.13 V between DA and UA,and 0.36 V between AA and UA.For simultaneous electrochemical detection of AA,DA and UA using differential pulse voltammetry,the linear range of 3DGLCFs/GCE for AA detection is 12.5-400μM,the linear range for DA is 0.05-10μM,and the linear range for UA is 0.05-15μM,with the detection limits(S/N=3) of 2μM for AA,0.01μM for DA,and 0.01μM for UA.The 3D GLCFs/GCE was also applied for the measurement of human serum,showing satisfactory recoveries.(5)Ruthenium ion-complexed carbonitride(Ru-C3N4) was found to show peroxidase activity and can catalyze the conversion of o-phenylenediamine to fluorescent 2,3-diaminophenazine in the presence of H2O2.The produced2,3-diaminophenazine also leads to apparent quenching of Ru-C3N4 fluorescence due to inner filter effect.These unique properties can be used to construct an effective ratio fluorescence platform for the detection of H2O2 and glucose with detection limits of 50 nM and 0.1μM,respectively.In addition,this method has been successfully used for the detection of glucose in human serum.This work provides a new ratiometric fluorescence platform for the detection of H2O2 and metabolites involving H2O2-generation reactions in the absence of HRP.