Electrochemical Performance Study Of Graphene-Based Material Modified Anode In Marine Benthic Microbial Fuel Cell

Microbial fuel cell (MFC) is a novel bioelectrochemical device for spontaneous conversion of biomass into electricity through the metabolic activity of the bacteria. On the anode, the organic matter is oxidized releasing electrons and protons. The electrons flow to the cathode through the external electric circuit producing electrical current; on the cathode, oxygen reacts with electrons and protons producing water. Marine benthic microbial fuel cell (BMFC) is one of novel concepts of the MFC, and the presented device is sustainable, environment friendly, and maintenance-free. It also can be used as the power of the underwater detecting instrument, and has important research significance. The problem with the MFC is that they are technically still very far from attaining acceptable levels of power output.The surface characteristic of anode materials has an important impact on battery performance. Recently, modification of the anode using different materials, which can be expected to facilitate bacterial adhesion and electron transfer to the anode surface, has been a successful approach for improving power production in studies for the BMFC. This thesis mainly adopts the graphene material modified anode, study the influence of the modified anode BMFC performance, the main research is as follows:(1) Graphene oxide (GO) and 2-hydroxy-1,4-naphthoquinone(HNQ) have been utilized to fabricate composite modified anode of which electrochemical performance is investigated. Results show that the kinetic activity of GO/HNQ modified anode is 6.58-fold higher than the blank, reaching 290.8 mA/m2. The power density of GO/HNQ modified cell reaches 346 mW/m2 and its 3.46-fold higher than blank one. Ultraviolet-visible spectra result indicates the characteristic absorption peaks of GO show significant red-shifts. It may be due to the π-π stacking between GO and HNQ. Finally, this paper proposes a new electron transfer mechanism between the modified anode and biofilm.(2) Using graphene/Fe3O4 composite materials modified anode, and compare the electrochemical performance with the blank anode. Results show that graphene/Fe3O4 modified anode has higher anti-polarization than the blank anode. The exchange current density of graphene/Fe3O4 modified anode reaches 346.77 mA/m2, kinetic activity is 9.8 times higher than that of the blank one. The maximum power density of graphene/Fe3O4 modified cell reaches 471.7 mW/m2, and is 2.9-fold greater than the blank. The synergy between graphene and Fe3O4 is the main theoretical basis to explain the excellent electrochemical performance.(3) The graphene is obtained by using chemical reduction method. Graphene with different quality (0.01 g,0.02 g,0.05 g) modify carbon felt anode. Results show that 0.05 g modified anode has the best anti-polarization performance and its maximum power reaches 471.7 mW/m2(0.01 g-312.9 mW/m2). Graphene can improve surface area of electrode, adhesion of bacteria and efficiency of electron transfer.