Microbiofuel cell powered by glucose/O2 based on electrodeposition of enzyme, conducting polymer and redox mediators. Part II: Influence of the electropolymerized monomer on the output power density and stability

In this study, we investigated the influence of nature of the electropolymerized monomer on the resulting power output and stability of a glucose/O2 powered biofuel cells (BFCs). The bioanode was prepared from a mixture of glucose oxidase-polymeric monomer-ferrocenium hexafluorophosphate-pyrroloquinoline quinone (abbreviated as, GOx-monomer-FHFP-PQQ) and the biocathode from laccase enzyme-polymeric monomer-4,4-sulfonyldiphenol-Bis-(bipyridine)-(5-aminophenanthroline) ruthenium bis (hexafluorophosphate) (abbreviated as, LAc-monomer-SDP-RuPy) electrodeposited from low conductivity solutions using pulsed square wave potentials (10 s at 4 V, then 3 s at 0.5 V) for 180 cycles. Three different monomers were investigated: aniline, phenol and pyridine. The power output of the aniline based BFCs reached 5.97 μW.mm−2 which is higher than the pyrrole based BFCs reported previously (3.17 μW.mm−2). With phenol monomer, the estimated maximum power density was only 0.276 μW.mm−2. The pyridine based BFCs showed the lowest power density (0.046 μW.mm−2) of all, even lower than the monomer-free BFC (0.124 μW.mm−2). The evaluation of the BFCs in buffer solution pH 7.4 under air at 37 °C for 3 days of continuous operation showed that pyrrole and aniline based BFCs are the most stable followed by phenol based BFCs. Pyridine and monomer-free BFCs undergo significant deterioration with up to 75% loss in power density.