Study Of Preparation And Electrocatalytic Performance Of Copper-based Composite Electrodes

There are a lot of copper distributed in nature and they have catalytic activity for many reactions. In this paper, two kinds of copper-based composite electrodes were obtained by electrochemical method. The copper-based composite electrodes’ applications in methanol fuel cells, enzyme glucose sensor and ethanol fuel cells were discussed.Because of the abundant fuel sources, easy storage and transport and high power density, direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) have a great application prospect in the direction of low-temperature fuel cells. Currently, Pt which is the main anode catalyst on the fuel cell has higher catalytic activity than other metals and good corrosion resistance in the fuel cell. However, Pt is expensive and with few resources. Therefore, it is necessary for us to develope a new type of less using and highly active catalyst in order to reduce the cost of fuel cell.Glucose monitoring has been of great interests for clinical analysis, food industry and biotechnology, but thermal and chemical instability of glucose oxidase prevent the fabricated enzymatic biosensors from being used for continuous monitoring. Non-enzymatic glucose sensor is relatively stable and less susceptible to interference, which have received continuously increasing interest in the recent years. It is significant to prepare the non-enzymatic glucose sensor which display a lot of advantages of faster response, higher sensitivity, lower detection limit, better stability and lower cost.In this thesis, we attempt to improve catalytic activity, CO-tolerance and stability by studying the structure of composite catalysts and support material. The methanol oxidation, glucose oxidation and ethanol oxidation properties of the as-prepared Cu/poly(2-amino-5-mercapto-1,3,4-thiadiazole)(Cu/PAMT) and Pt-Cu catalysts were studied. The main studying comprises three parts, as follows:(1)The conductive polymer film PAMT was electropolymerized on solid carbon paste electrode by cyclic voltammetry, and nano-copper particles with more active sites were electrodeposited on conductive polymer film by potentiostatic electrodeposition with a gentle evolution of hydrogen. The micrograph and crystal form of Cu/PAMT/sCPE nanoparticles were characterized by scanning electron microscopy and X-ray diffractometer, respectively. The electrocatalytic activity and stability of Cu/PAMT/sCPE electrode for methanol oxidation were investigated by cyclic voltammetry, electrochemical impedance spectrum and chronoamperometry in alkaline electrolytes. It turned out that Cu/PAMT/sCPE electrode show higher electrocatalytic activity and stability than Cu/sCPE electrode.(2)The composite electrodes prepared by the same method were used for glucose sensor. The electrocatalytic activity and stability of Cu/PAMT/sCPE for glucose oxidation were investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry in alkaline electrolytes. It turned out that Cu/PAMT/sCPE show higher sensitivity, lower detection limits than Cu/sCPE.(3)The nano-copper particles with more active sites were electrodeposited on solid carbon paste electrode by potentiostatic electrodeposition, and Pt particles were electrodeposited on nano-cooper particles. The Pt-Cu catalyst was prepared by dispersing Pt with more active sites of copper particles. The micrograph of Pt-Cu/sCPE nanoparticles was characterized by scanning electron microscopy. The Pt particle size was greatly reduced and the specific surface area of Pt was greatly increased, which improved the catalytic activity of ethanol oxidation.