Biofuel cell

The concept of biofuel cells was briefly mentioned in Chapter 2, section 2.1.6, where microbial sensitisers were employed in photoelectrochemical devices. 

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An exciting emerging technology is the biofuel cell. A biofuel cell is like a conventional fuel cell however, in place... 

Second, sensors are often intended for a single use, or for usage over periods of one week or less, and enzymes are capable of excellent performance over these time scales, provided that they are maintained in a nfild environment at moderate temperature and with minimal physical stress. Stabilization of enzymes on conducting surfaces over longer periods of time presents a considerable challenge, since enzymes may be subject to denaturation or inactivation. In addition, the need to feed reactants to the biofuel cell means that convection and therefore viscous shear are often present in working fuel cells. Application of shear to a soft material such as a protein-based film can lead to accelerated degradation due to shear stress [Binyamin and Heller, 1999]. However, enzymes on surfaces have been demonstrated to be stable for several months (see below). 

Fuel cells based on unmediated electrocatalysis by heme-containing sugar dehydrogenases have not yet been tested in biological fluids, but may be useful for implantable applications, as they avoid the need for toxic or expensive mediators and have minimal design constraints. Realistically, the lifetime of biofuel cells is still insufficient for biomedical applications requiring surgical installation. 

Of direct interest for biofuel cell applications are the reported reduction of O2 by multi-copper oxidases on carbon nanotube electrodes [Yan et al., 2006 Zheng et al., 2006] and the oxidation of H2 by hydrogenase covalently bound to carbon nanotubes [Alonso-Lomillo et al., 2007]. The hydrogenase/nanotube anode is extremely stable (>1 month), and shows 33-fold enhanced enzyme coverage compared with similarly treated graphite of the corresponding geometric surface area. A. vinosum... 

Akers NL, Moore CM, Minteer SD. 2005. Development of alcohol/02 biofuel cells using salt-extracted tetrabutylammoiuum bromide/Nafion membranes to immobilize dehydrogenase enzymes. Electrochim Acta 50 2521-2525. 

Barton SC, Gallaway J, Atanassov P. 2004. Enzymatic biofuel cells for implantable and microscale devices. Chem Rev 104 4867-4886. 

Heller A. 2004. Miniature biofuel cells. Phys Chem Chem Phys 6 209 -216. 

Kamitaka Y, Tsujimura S, Setoyama N, Kajino T, Kano K. 2007. Fructose/dioxygen biofuel cell based on direct electron transfer-type bioelectrocatalysis. Phys Chem Chem Phys 9 1793-1801. 

Katz E, Willner I, Kotlyar AB. 1999. A non-compartmentalized glucose IO2 biofuel cell by... 

Mano N, Mao F, Heller A. 2003. Characteristics of a miniature compartment-less glucose-02 biofuel cell and its operation in a living plant. J Am Chem Soc 125 6588-6594. 

Okuda J, Yamazaki T, Fukasawa M, Kakehi N, Sode K. 2007. The application of engineered glucose dehydrogenase to a direct electron-transfer-type continuous glucose monitoring system and a compartmentless biofuel cell. Anal Lett 40 431 -440. 

Pahnore GTR, Kim H-H. 1999. Electro-enzymic reduction of dioxygen to water in the cathode compartment of a biofuel cell. J Electroanal Chem 464 110-117. 

Pahnore GTR, Bertschy H, Bergens SH, Whitesides GM. 1998. A methanol/dioxygen biofuel cell that uses NAD -dependent dehydrogenases as catalysts Application of an electro-enzymatic method to regenerate nicotinamide adenine dinucleotide at low overpotentials. J Electroanal Chem 443 155-161. 

Soukhaiev V, Mano N, Heller A. 2004. A four-electron 02-electroreduction biocatalyst superior to platinum and a biofuel cell operating at 0.88 V. J Am Chem Soc 126 8368-8369. 

Topcagic S, Minteer SD. 2006. Development of a membraneless ethanol/oxygen biofuel cell. Electrochim Acta 51 2168-2172. 

Yan YM, Zheng W, Su L, Mao LQ. 2006. Carbon-nanotube-based glucose/02 biofuel cells. Adv Mater 18 2639-2643. 

Moreover, it has been demonstrated that CNTs promote the direct electrochemistry of enzymes. Dong and coworkers have reported the direct electrochemistry of microperoxidase 11 (MP-11) using CNT-modified GC electrodes [101] and layer-by-layer self-assembled films of chitosan and CNTs [102], The immobilized MP-11 has retained its bioelectrocatalytic activity for the reduction of H202 and 02, which can be used in biosensors or biofuel cells. The direct electrochemistry of catalase at the CNT-modified gold and GC electrodes has also been reported [103-104], The electron transfer rate involving the heme Fe(III)/Fe(II) redox couple for catalase on the CNT-modified electrode is much faster than that on an unmodified electrode or other... 

Fig. 7.7 Biodiesel, methanol, ethanol, glueose and glycerol to electricity via biofuel cell...

Enzymatic Biofuel Cells for Implantable and Microscale Devices Scott Calabrese Barton, Josh Gallaway, and Plamen Atanassov pp 4867 - 4886 (Review) DOl 10.1021/cr020719k... 

In an effort to use biological energy transduction to miniaturize a biofuel cell for in vivo applications, Heller and co-workers have created membraneless, caseless cells that can function under physiological... 

Recently a new hybrid power source has been reported that couples oxidation at a dye-photosensitized nanocrystalline semiconducting SnOz photoanode with the enzyme-catalyzed reduction of O2. Although miniaturization has not yet been reported for this new hybrid, the developments already achieved to miniaturize biofuel cells coupled to those being developed for charge-insertion oxides should be technically transferable to this system. 

Enzymatic Biofuel Cells for Implantable and Microscale Devices... 

Bioelectrochemistry at the Cathode and Anode of 4871 Enzymatic Biofuel Cells... 

Biological fuel cells have a long history in the literature,but in recent years, they have come to prominence as more conventional fuel cell technologies have approached mass-market acceptance. Driving the recent ascendance of biofuel cells are the aspects of biocatalysis that are unmatched by conventional low-temperature oxidation—reduction catalysts, namely, activity at near-room temperatures and neutral pH and, more importantly, selective catalytic activity. 

In contrast, stability is a key aspect of any practical fuel cell, and biofuel cells must have lifetimes ranging from months to years to justify implanted, highly distributed, or consumer portable applications. Such stability is often difficult to achieve in redox enzymes, although introduction of thermophilic species and the use of mutagenic techniques might provide future... 

Josh Gallaway was born in Waverly, TN, in 1974 and lived there until attending Case Western Reserve University in 1992, where he earned a B.S. in chemical engineering. Since 2002, he has been a graduate student at Columbia University, studying redox polymer-enzyme systems for use in biofuel cells. 

We begin with a discussion of key applications that can be addressed by biofuel cells and key requirements derived therefrom. The range of possible applications can be broken down into three main... 

Figure 1. Conceptual product definitions of enzyme-based biofuel cells as they are compared in their specific energy and energy density to the existing primary battery technology. Based on Figure 2 of ref 15. Reproduced with permission. Copyright 1999 The Electrochemical Society, Inc.

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