Optimization of a Membraneless Glucose/Oxygen Enzymatic Fuel Cell Based on a Bioanode with High Coulombic Efficiency and Current Density

After initial testing and optimization of anode biocatalysts, a membraneless glucose/oxygen enzymatic biofuel cell possessing high coulombic efficiency and power output was fabricated and characterized. Agaricus meleagris (AmPDH) and flavodehydrogenase domains of various cellobiose dehydrogenases (DHCDH) were tested during the pre-screening. Myrothecium verrucaria adsorbed on graphite. Optimization showed that the current density for the mixed enzyme electrode could be further improved by using a genetically engineered variant of the non-glycosylated flavodehydrogenase domain of cellobiose dehydrogenase from Corynascus thermophilus expressed in E. coli (ngDH(CtCDHC310Y)) with a high glucose-turnover rate in combination with an Os-complex-modified redox polymer with a high concentration of Os complexes as well as a low-density graphite electrode. AmPDH/ngDH(CtCDHC310Y) anode showed not only a similar maximum voltage as with the biofuel cell based only on the ngDH(CtCDHC310Y) anode (0.55 V) but also a substantially improved maximum power output (20 Wcm(-2)) at 300 mV cell voltage in air-saturated physiological buffer. Most importantly, the estimated half-life of the mixed biofuel cell can reach up to 12 h, which is apparently longer than that of a biofuel cell in which the bioanode is based on only one single enzyme. (Less)