Abstract
Carbon nanotubes (CNTs) and polyelectrolyte poly(allylamine hydrochloride) (PAH) composite modified indium tin oxide (ITO) electrodes, by a layer-by-layer (LBL) self-assembly technique, was evaluated as an anode for microbial fuel cells (MFCs). The bioelectrochemistry of Shewanella loihica PV-4 in an electrochemical cell and the electricity generation performance of MFCs with multilayer (CNTs/PAH)n-deposited ITO electrodes as an anode were investigated. Experimental results showed that the current density generated on the multilayer modified electrode increased initially and then decreased as the deposition of the number of layers (n = 12) increased. Chronoamperometric results showed that the highest peak current density of 34.85 ± 2.80 mA/m2 was generated on the multilayer (CNTs/PAH)9-deposited ITO electrode, of which the redox peak current of cyclic voltammetry was also significantly enhanced. Electrochemical impedance spectroscopy analyses showed a well-formed nanostructure porous film on the surface of the multilayer modified electrode. Compared with the plain ITO electrode, the multilayered (CNTs/PAH)9 anodic modification improved the power density of the dual-compartment MFC by 29%, due to the appropriate proportion of CNTs and PAH, as well as the porous nanostructure on the electrodes.
Highlights
Microbial fuel cells (MFCs) are a type of bioreactor, which directly harvests electricity from chemical energy by exoelectrogens.Recently, they have been widely used in power generation, wastewater treatment and biosensors [1,2,3,4,5,6,7].In particular, the electron transfer occurs between: Redox-active outer membrane c-type cytochromes (OM c-Cyts) of the microbe, or redox-active mediators secreted by the cells/added outside, or microbially generated nanowires and the electrode surface [8]
As the bilayer number of the composite films increased, the absorbance at 430 nm—arising from the Carbon nanotubes (CNTs)—increased. This indicated that CNTs with carboxylic acid groups were well-assembled with poly(allylamine hydrochloride) (PAH) to form composite films and that the number of CNTs corresponding with the electrode thickness increased with the increase of bilayer number, during the assembly process of the (CNTs/PAH)n -deposited indium tin oxide (ITO) electrode [33]
CNTs/PAH multilayer deposition on an ITO anode by the LBL self-assembly technique was successfully prepared in the present study
Summary
Microbial fuel cells (MFCs) are a type of bioreactor, which directly harvests electricity from chemical energy by exoelectrogens (i.e., microorganisms transferring electrons to an electrode) They have been widely used in power generation, wastewater treatment and biosensors [1,2,3,4,5,6,7]. Indium tin oxide (ITO) has a potential high-impact due to its high electrical conductivity, optical transparency, and promising application in electrochemical devices It has been widely utilized as a substrate for the adsorption of biomolecules, and a working electrode to explore the electron transfer between exoelectrogens and the electrode surface in the bioelectrochemical system [30,31]. The electrochemical catalytic activity of the multilayered film (CNTs/PAH)n -deposited ITO electrode in the bioelectrochemical system and its electricity generation performance in MFCs with Shewanella loihica PV-4 as the electricigen were elucidated. The effect of CNT toxicity on the electrochemical activity and cell proliferation of S. loihica PV-4, as well as the cell attachments on the electrode in the MFCs were studied
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