(Invited) Glucose/Oxygen Wearable Biofuel Cells Based on Poly(glycidyl methacrylate)-Grafted MgO-Templated Porous Carbon

Abstract

There are a lot of recent researches on high power enzymatic glucose/O2 biofuel cells (BFCs). We have reported that the use of MgO-templated porous carbon (MgOC) at the electrodes of biofuel cells dramatically improves the output power [1-4]. Using MgOC can improve the effective electrode surface area, leading to increased current density and output density. Supporting enzymes on these types of porous materials is expected to lead to increased output density. In the past researches [1-4], the enzymes physically adsorbed inside the porous carbon gradually leach from the carbon surface after long-term operation or during the replacement of the fuel solution.In this study, to prevent enzyme leakage, the enzyme or mediator were immobilized on the MgOC surface via multipoint covalent bonding; the grafting of polymers bearing pendant glycidyl groups was achieved by the polymerization of glycidyl methacrylate (GMA), initiated by electron beam irradiation on the carbon surface. Poly(glycidyl methacrylate) (poly(GMA)) bearing pendant glycidyl groups, grafted on the surface of MgO-templated carbon, is useful for forming strong multipoint covalent bonds with amino functional groups on the surface of flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH), Azure A and aminoferrocene.For example, the immobilized FAD-GDH can generate glucose-oxidation catalytic current using 1,2-naphthoquinone (12NQ) as the redox mediator, which is also captured on the electrode surface. The catalytic current is more stable than that obtained using the FAD-GDH-MgOC electrode without poly(GMA) because the leaching of FAD-GDH and 12NQ is suppressed by the enzyme capping effect.The BFC performance using the anode measured in 1.0 M phosphate buffer (PBS) containing 100 mM glucose exhibited the open circuit voltage of 0.8 V, maximum power density of 1.4 mW/cm2, and maximum current density of 4.25 mA/cm2.In the present paper, we totally discuss three types glucose/oxygen biofuel cells based on the poly(glycidyl methacrylate)-grafted MgO-templated porous carbon.