Electrochemical polymerization of hydroquinone on graphite felt as a pseudocapacitive material for application in a microbial fuel cell

Abstract

Here we reported the use of electropolymerization to achieve the transformation of aqueous hydroquinone to solid-phase polyhydroquinone (PHQ) with pseudocapacitive characteristics, and the application of this redox-active product to shuttle electron transfer in the anode system of a microbial fuel cell (MFC). The microscopic and spectroscopic results showed that the treatment of the graphite felt (GF) substrate with acids was effective in improving the amounts of surface-bound oxygen-containing groups, enabling better adhesion of PHQ onto the GF surfaces. The electrochemical measurements indicated that the resulting PHQ-AGF (acid treated GF) possessed high pseudocapacitance due to the fast and reversible redox cycling between hydroquinone and benzoquinone. The MFC equipped with the PHQ-AGF anode achieved a maximum power density of 633.6 mW m-2, which was much higher than 368.2, 228.8, and 119.7 mW m-2 corresponding to the MFC with the reference PHQ-GF, AGF, and GF anodes, respectively. The increase in the power performance was attributed to the incorporation of the redox-active PHQ abundant in C-OH and C=O groups that were beneficial to the increased extracellular electron transfer and enhanced bacterial adhesion on the anode.