Study On The Electrodes Of Enzymetic Biofuel Cells Based On The Carbon Nanotubes

Biofuel cells (BFC) are one kind of effective devices which could directly convertthe chemical energy into electrical energy. According to the bio-catalysts used in thebiofuel cells, the biofuel cells can be divided into microbe organism biofuel cells(MBFC) with microbe as the catalysis and enzyme biofuel cells (EBFC) with purifiedenzyme as the catalysis. In recent years, EBFC are attracting more and more attentionbecause of their various desirable properties such as low cost, low corrosive of theelectrolyte and good biocompatible. The major barriers to the practical application ofthe biofuel cells are the low energy output and the poor stability of the enzymeelectrodes, which are related to the enzyme and mediator immobilization and thematrix for enzyme and mediators immobilization. In order to improve the performance,searching for the compatible materials and effective methods for the immobilization ofenzyme and mediator on the electrodes is the key issue in the procedure forconstructing high-performance biofuel cells. In this paper, several methods for surfacemodification of carbon nanotubes (CNTs) have been developed and bioenzyme andmediator have been successfully immobilized on the electrodes. Additionally, theperformance of the resulted enzyme electrodes and the corresponding biofuel cells hasbeen studied in detail. The main points are summarized as follows:(1) CNTs were noncovalent-functionalized with the1-Pyreneformaldehyde (1-PA)through the π-π stockpiling interaction and were used to immobilize laccase (LAC).The electrocatalytic properties of the LAC immobilized on the PA fuctionalized CNTs(LAC/PA-CNTs) for oxygen reduction has been investigated by cyclic voltammetry(CV).At the same experimental condition, the LAC/PA-CNTs electrodes shows higherelectrocatalytic activity than the LAC immobilized on the pristine CNTs (LAC/CNTs)The LAC/PA-CNTs electrode was combined with the glucose oxidase (GOD)immobilized on CNTs (GOD/CNTs) modified glassy carbon electrode to constructingbiofuel cells shows higher performance.(2) The acidficational CNTs functionalized with β-cyclodextrin (β-CD) was usedto immobilize ferrocene (Fc) froming the CNTs-CD-Fc nanocomposites. TheCNTs-CD-Fc nanocomposites were mixed with the GOD, crosslinked withglutaraldehyde to form big enzyme clusters and obtain GOD/CNTs-CD-Fc electrode.The electrocatalytic properties of the electrode for glucose oxidation have been investigated by cyclic voltammetry (CV). The GOD/CNTs-CD-Fc electrode shows thehigher electrocatalytic activity than the GOD/CNTs-Fc electrode under the sameexperimental condition. The GOD/CNTs-CD-Fc electrode and GOD/CNTs-Fcelectrode were combined with the commercial E-ETK Pt/C modified glassy carbonelectrode to constructing biofuel cells, the performance of the former BFC is higherthan the latter’s.(3) The CNTs functionalized with ethanediamine (EDA) were used to immobilizethe Ferrocenecarboxaldehyde (Fc, CNTs-Fc), silk film (SF) was used to immobilizeglucose oxidase with the GA as the cross-linking agent (SF-GOD). The CNTs-Fc wasmixed with the SF-GOD, coated on the glassy carbon electrode, and forming theCNTs-Fc/SF-GOD electrode. The resulting electrode exhibited good catalytic activitytowards glucose oxidation and excellent stability. For the assembled glucose/O2BFCwith the CNTs-Fc/SF-GOD electrode as the bioanode and a commercial E-TEK Pt/Cmodified glassy carbon electrode as the cathode, the open circuit potential is0.48Vand the maximum power density of50.70μW cm-2.