High Power Glucose/O₂ Biofuel Cell Constructed from MgO-Temlated Carbon Modified Carbon Cloth

Abstract

Enzymatic biofuel cells (EBFCs) based on enzyme electrocatalysts are devices to directly convert chemical energy of glucose and alcohol to electronical energy. EBFCs gather attention as a power source of wearable electronic sensor devices because they have high biocompatibility. In this paper, we report a glucose/O2 EBFC using flexible carbon cloth electrodes modified with mesoporous carbon particle, which shows high power density as high as 2 mW cm-2. Moreover, the capacity of the BFCs can be controlled by the mole number of glucose added. Porous carbon electrode was fabricated by modifying the MgO-templated mesoporous carbon (MgOC) on carbon cloth in order to enlarge surface area and to immobilize enzyme and redox mediator on electrode surface. MgOC is a kind of pore size-controlled porous carbon; mesopore size can be controlled by alternating the MgO template size. For the anode catalyst, flavin adenine dinucleotide dependent glucose dehydrogenase (FAD-GDH) from Aspergillus terreus was used. Naphthoquinones (NQ) were used as anode mediator. FAD-GDH and NQ were modified on the anode 0.19 and 1.5 mg cm-2, respectively. For the oxygen-reducing cathode, bilirubin oxidase (BOD) was used as enzyme, and 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS) as mediator. BOD and ABTS were modified on the cathode 1.25 and 1.25 mg cm-2, respectively. 1.0 M phosphate buffer (pH = 7.0) was used as an electrolyte. A cellophane sheet was sandwiched between the anode and cathode as a separator. Figure 1 shows the cell power (solid lines) and cell voltage (broken lines) as a function of current density of the EBFCs. The maximum output power density of BFCs using 1,2-NQ and 1,4-NQ for anode mediators were 1.69 and 2.06 mW cm-2, receptively, because the redox potential of 1,4-NQ is more negative than that of 1,2-NQ. Figure 2 shows the cell capacity of the BFCs as a function of glucose concentration added to the cell. The capacity of the cell increased linear with an increase of the mole number of glucose. Figure 1

Amphiphilic Polymer Mediators Promoting Electron Transfer on Bioanodes with PQQ-Dependent Glucose Dehydrogenase

“…These results indicate that the amphiphilic polymer mediators LP-1 and BP-1 with long PEG chains can significantly facilitate electron-transfer processes from the active site of the enzyme to the electrode surface. The current density for LP-1 was comparable to the highest current density reported in recent studies based on PQQ–GDH, , although higher current densities have been achieved by using other enzymatic reaction systems such as flavine adenine dinucleotide (FAD)-dependent glucose dehydrogenase Figure f shows the relationship between glucose concentration and catalytic currents for the bioanode incorporating mPMS or LP-1.…”

“…The current density for LP-1 was comparable to the highest current density reported in recent studies based on PQQ−GDH, 27,38 although higher current densities have been achieved by using other enzymatic reaction systems such as flavine adenine dinucleotide (FAD)-dependent glucose dehydrogenase. 39 Figure 5f shows the relationship between glucose concentration and catalytic currents for the bioanode incorporating mPMS or LP-1. The catalytic currents are saturated at glucose concentrations of 50− 100 mM.…”