Preparation And Application Of Modified Electrode By Immobilized Horseradish Peroxidase In Enzymatic Biofuel Cell

As a new energy source, biofuel cell (BFC) is classified into two types: microbial fuel cell (MFC) and enzymatic biofuel cell (EFC). EFC has become the investigating hotspot in recent two years because of its higher production. For a long time, small output of EFC is a bottleneck for its development. Modifying anode electrode can prompte electron transfer from enzyme to anode and thus improve the electricity production of EFC. It has become keystone of research in EFC. In this paper, the preparation and application in the enzymatic biofuel cell of horseradish peroxidase (HRP) immobilized on layered double hydroxides (LDH) and multiwall carbon nanotubes (MWNT) were investigated. The main research work is as follows:1. Ni-Al-NO3 LDHs with a Ni/Al molar ratio of 3.0 were synthesized by the coprecipitation method and used as carrier for HRP immobilization in order to modify glassy carbon (GC) electrodes. Then the enzymatic biofuel cell was constructed with HRP/LDH/GC electrode as anode for the purpose of studying the power output and direct electron transfer between the redox centers of HRP and the anode surface. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) showed that HRP was successfully intercalated into LDH, and the HRP/LDH film had an ordered structure with a uniform, porous morphology. The conformational changes of HRP when interacting with LDH were investigated utilizing both Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) characterization. The results demonstrated that HRP retained the basic enzymatic activity with the ratio of alpha-helix reduced a little and ratio of beta-sheet increased. This conformational change is highly likely account for the DET between HRP and anode, which is demonstrated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and polarization curve measurement.2. Carbon paper (TP) electrode was modified utilizing a layer-by-layer (LBL) assemble technique and the performance of the modified electrode (HRP/MWNT/TP) as an anode in enzymatic biofuel cell was investigated. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) showed that LBL-assembled MWNT composite films has formed on TP surface and also clearly demonstrated the successful immobilization of HRP onto the modified electrode. FTIR and CD characterization revealed that HRP/MWNT retained its basic enzymaticactivity with the ratio of alpha-helix reduced a little. According to CV, EIS and polarization curve measurements, with the modified anode, the enzymatic biofuel cell produced a higher power density comparing to the bare TP anode, which confirmed that MWNT facilitate electron transfer in the enzymatic biofuel cell system.