Construction And Performance Study Of Enzyme Electrodes For Glucose Biofuel Cell

Biofuel cells(BFCs),especially enzyme biofuel cells(EBFCs),as a kind of green new energy devices,have attracted the attention of researchers in recent years.With the crisis of traditional energy and environmental pollution,people pay more and more attention to clean new energy.Considering the mild operating conditions,high energy conversion efficiency and extensive fuel sources,EBFCs are expected to provide energy for wearable devices such as cardiac pacemakers.Howe'ver,due to the complexity for the preparation of the enzyme electrodes and the limitations of the devices,the fabrication of high performance EBFCs is still one of the research hotspots at home and abroad.Starting from the preparation materials and methods of enzyme electrode,around the key issues of how to improve the performance of enzyme electrode,the study of the effective immobilization of enzyme as well as the enhancement of electron transfer rate between enzyme activity center and electrode surface was carried out in this paper.Besides,using the product of the enzyme anode,namely hydrogen peroxide(H2O2)as the fuel of the enzyme cathode,a glucose EBFC with a certain output power was obtained.The main research contents are as follows:(1)Preparation and study of glucose oxidase(GOx)-based enzyme anode.The enzyme active center of GOx was deeply buried inside its protein shell,limiting the electron transfer from its active center to the electrode surface.Therefore,using multi-walled carbon nanotubes(MWCNTs),combining small biomolecule chitosan(CS)and cross-linking agent glutaraldehyde(GA)to successfully immobilize GOx on the electrode,a GOx modified electrode of direct electron transfer type was prepared in this chapter.And the electrochemical behavior of the enzyme anode was studied later.The results showed that the electrochemical reaction of GOx on the electrode was a surface-controlled process,the constant ks of the direct electron transfer rate of GOx on the electrode surface was 1.47 s-1,and after a period of cyclic voltammetry scanning,the oxidation peak current density of the electrode only decreased by 9.8%.The results showed that the use of MWCNTs facilitated the transfer of electrons from the active center of GOx to the electrode surface.And the utilization of CS/GA,the immobilization of GOx on electrode modified with MWCNTs exhibited good activity.(2)Preparation and study of horseradish peroxidase(HRP)-based enzyme cathode.The choices of the immobilized enzyme carriers,the redox mediators as well as the methods for immobilizing enzyme all have a great influence on the performance of the enzyme cathode.In this paper,carbon nanotubes were employed as solid support.The mixture of MWCNTs and tetrathiafulvalene(MWCNTs/TTF)was used to increase the electron transfer rate between the enzyme and the electrode,and the HRP was fixed using the covalent cross-linking method with CS/GA.The enzyme cathode MWCNTs/TTF-HRP was prepared and the performance of the enzyme cathode was studied.The results showed that the mixture MWCNTs/TTF had better electron transport efficiency than MWCNTs alone,and the constructed enzyme cathode showed good catalytic reduction to H2O2.Besides,the stability of the electrode was better.After the cyclic voltammetry scanning of 50 cycles,the reduction peak current density decreased by only 14.3%.The above results indicated that the mixture MWCNTs/TTF was expected to be used in the modification of the enzyme electrode.(3)With carbon paper as base electrode,a glucose EBFC was constructed.In this chapter,the carbon paper electrode was used as the base electrode.And,the anode MWCNTs-GOx and cathode MWCNTs/TTF-HRP were constructed according to the enzyme electrode preparation methods in Chapters 2 and 3,respectively.With the electrodes fabricated above,a EBFC was assembled,which produced a maximum current density of 55.74 ?A/cm2,a maximum power density of 5.76 ?W/cm2 and an open circuit voltage of 0.4 V,respectively.The above results indicated that based on carbon paper electrode,using H2O2 produced by the anode as the fuel of the cathode,a glucose EBFC with relatively simple device in structure could be successfully constructed.And the idea of using the product of the anode as the fuel of the cathode was verified,which laid a foundation for further research of EBFC.