Fabrication Of Porous Carbon Based Composites And Their Application In Electrochemical Sensor

The porous carbon materials have received wide attention due to their excellent physical and chemical properties,such as high gas-liquid permeability,good electrical conductivity,excellent thermodynamics and chemical stability.Furthermore,using the advantages of different sized pore structures,the porous carbon materials can promote the uniform dispersion of functional sites on larger contact area,and thus achieve efficient material transmission or storage.In addition,the introduction of transition metal compounds and doping of functional heteroatoms can not only improve the physical and chemical properties of carbon materials,but also give more abundant functions to them.Therefore,for different application scenarios,using simple and effective synthesis strategies to precisely control the pore characteristics and design novel porous carbon-based materials with specific functions can promote the application of carbon materials in electrochemistry field.Based on the sensing application of porous carbon materials,four kinds of porous carbon matrix composites were designed and prepared in this thesis,and their electrocatalytic activity and sensing performance were studied systematically.The specific research work is as follows:1.A novel hierarchical boron/nitrogen co-doped yolk-shell hollow mesoporous carbon nanospheres(Yolk-shell B,N-MCNSs)was developed through a“hard template”method,which were loaded on the reduced graphene oxide(r GO)surface.The heteroatom doping contributes to improving the conductivity of the carbon framework,while the introduction of r GO as a substrate can promote electron transport and increase the dispersion of B,N-MCNSs.B,N-MCNSs/r GO has unique three-dimensional porous structure,which can not only provide more active sites for electrochemical reaction,but also provide favorable transport paths for the penetration of electrons,ions and biomolecules.Benefiting from the internal advantages and unique structural features,B,N-MCNSs/r GO sensor exhibited wide linear range(0.0915–103?M and 0.0822–128?M),low detection limit(0.0503?M and 0.0462?M),strong anti-interference ability and good stability for the detection of xanthine(XA)and guanosine(GUA).2.A novel flower-like Zn O/3D graphene@Fc hybrid was designed and synthesized using a one-pot in situ hydrothermal growth method.The unique lamellar structure of GO provided a skeleton for the formation of three-dimensional carbon,which can solve the problems of Zn O nanoparticles,such as easy to agglomeration,liable to fall off and instability.Benefiting from the unique structural advantages,and combining with the synergistic effect between components,the flower-like Zn O/3D graphene@Fc exhibited excellent sensing performance for epinephrine(EP)and its oxidation derivatives(QA)with a wide linear range(0.02–216?M),low detection limit(0.0093?M),strong anti-interference and good stability.Acceptable recovery obtained from the real sample test,confirmed the feasibility of the biosensor for practical application.3.A self-assembly strategy was presented for the synthesis of cobalt phosphide(Co P_x)embedded into 3D phosphorus/nitrogen co-doped reticular porous carbon frameworks(Co P_x@P,N-RPCs)utilizing polyacrylonitrile(PAN)as the nitrogen doping carbon source and hypophosphite as a phosphorus source via hydrothermal method and subsequent phosphorization.The obtained Co P_x@P,N-RPCs owned obvious three-dimensional hierarchical porous structure and large electrode/electrolyte contact area.In addition,Co P_x was encapsulated into the phosphorus/nitrogen co-doped carbon network,preventing its agglomeration and free growth,improving the structural stability and conductivity of Co P_x,and alleviating the volume expansion/contraction effect.Under the synergistic effect between the components,Co P_x@P,N-RPCs showed a low detection of limit(0.005?M)for nitrite detection,which is far better than the national standard of China(0.1?M).Meanwhile,this work provided a new synthesis path for the development of high-performance porous carbon-based nanocomposite.4.A novel electrochemical nanocomposite,(Ni,Fe)Se_x/N-PCNs,was constructed by in situ encapsulating of Ni-Fe bimetallic selenides into nitrogen doped porous carbon nanosheets using the hydrothermal method,acid etching treatment and pyrolytic selenization process with Ni-Fe LDH as substrate and metal organic framework(ZIF-67)as sacrificial template.The porous carbon nanosheets are rich in pore size and possess highly conductive three-dimensional lattices.Meanwhile,the nickel-iron element was converted into bimetallic selenides with high chemical activity by means of pyrolytic selenization,which solves the complicated,time-consuming and environmental problem in the selenides synthesis process.Based on the above structural characteristics,(Ni,Fe)Se_x/N-PCNs showed excellent sensing performance for GUA detection,with a low detection limit(0.012?M),wide linear range(0.053–227?M),excellent stability and strong anti-interference.This work also provided an ingenious idea for the development and preparation of 3D porous carbon@selenide composites using LDHs/ZIF as precursors.