Fabrication Of Transition Metal(Oxide) Composites And Their Applications In Electrochemical Sensors

The transition metal and their composition materials have attracted a great deal of attentions in many fields,including energy storage,photocatalysis,and electrocatalysis,due to their unique structural characteristics and excellent catalytic performance.Although in the field of electrochemistry,researchers have been studying transition metal composites for many years,it is still a great task to design the morphology and structure of the composites as well as to improve their electrocatalytic performance.In this dissertation,transition metal oxides and alloy were synthesized by different strategies and applied in electrochemical sensors.The morphology and structure of the composites were studied by X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectroscopy,scanning electron microscopy,and transmission electron microscopy.The electrocatalytic performance and electrochemical behavior of electrode surface of the biosensor were investigated by cyclic voltammetry,current-time method and electrochemical impedance spectroscopy.The research content includes the following four aspects:1.The spinel structured ZnMn₂O₄ was synthesized by a facile and environment-friendly solvothermal technique.A series of techniques were employed to characterize the structure and morphology of the composite.Then,the as synthesized composites were modified on GCE used as enzyme mimics for the electrocatalytic reduction of hydrogen peroxide.The sensor based on ZnMn₂O₄ performed excellent catalytical activity towards the electroreduction of H₂O₂.Under optimized conditions,the ZnMn₂O₄/GCE displayed a linear amperometric response for H₂O₂ in a wide concentration range of 0.02-15 m M as well as good anti-interference ability and stability.In addition,the proposed sensor was successfully applied for the determination of H₂O₂ in milk,indicating its potential value in electrochemical sensor applications.2.Owning to its excellent conductivity,reduced graphene oxide（rGO）was induced into ZnMn₂O₄.Herein,reduced graphene oxide wrapped ZnMn₂O₄microspheres（ZnMn₂O₄@rGO）were facilely synthesized through solvothermal technique.The microstructure and morphology of ZnMn₂O₄@rGO microspheres were analyzed under various characterization methods.Meanwhile,the synthesized ZnMn₂O₄@rGO was employed as excellent electrocatalyst for the reduction of hydrogen peroxide.The introduction of reduced graphene oxide enhanced the electrocatalytic performance of the sensor.Thus,ZnMn₂O₄@rGO/GCE exhibited a linear detection to H₂O₂ in a wide concentration range of 0.03-6000μM with a detection limit of 0.012μM.The biosensor was evaluated to determine H₂O₂ secreted by human breast cancer cells,indicating its promising applications in physiology and diagnosis.3.The hetero-structured reduced graphene oxide wrapped MnO-Mn₃O₄（MnO-Mn₃O₄@rGO）composite was prepared by a facile solvothermal-calcination treatment.Due to the synergism of MnO and Mn₃O₄ and the good conductivity of rGO,the MnO-Mn₃O₄@rGO based biosensor exhibited excellent catalytic performance for H₂O₂ with a wide linear range of 4-17000μM,and low detection limit of 0.1μM.In addition,the sensor also displayed good anti-interference ability and stability.The detection of H₂O₂in tomato sauce suggested that the sensor has practical application value.4.3D structured Cu-Sn alloy with carbon fiber paper（CP）as the substrate was fabricated via a co-electrodeposition method.The composition,structure,and morphology of Cu-Sn alloy were characterized by a series of techniques.Compared with pure copper and tin,the biosensor based on Cu-Sn alloy（Cu-Sn/CP）exhibited excellent catalytic performance towards glucose detection.The as-prepared biosensor showed a good linear range from 0.5 to 10000μM,and the detection limit was 0.16μM.The biosensor also suggested good selectivity and stability.Meanwhile,it was used for the detection of human serum,which displays its potential practical value.