Abstract
The construction of optimized biological fuel cells requires a cathode which combines the longevity of a microbial catalyst with the current density of an enzymatic catalyst. Laccase-secreting fungi were grown directly on the cathode of a biological fuel cell to facilitate the exchange of inactive enzymes with active enzymes, with the goal of extending the lifetime of laccase cathodes. Directly incorporating the laccase-producing fungus at the cathode extends the operational lifetime of laccase cathodes while eliminating the need for frequent replenishment of the electrolyte. The hybrid microbial–enzymatic cathode addresses the issue of enzyme inactivation by using the natural ability of fungi to exchange inactive laccases at the cathode with active laccases. Finally, enzyme adsorption was increased through the use of a functionally graded coating containing an optimized ratio of titanium dioxide nanoparticles and single-walled carbon nanotubes. The hybrid microbial–enzymatic fuel cell combines the higher current density of enzymatic fuel cells with the longevity of microbial fuel cells, and demonstrates the feasibility of a self-regenerating fuel cell in which inactive laccases are continuously exchanged with active laccases.
Highlights
Biological fuel cells (BFCs) use bioderived fuels and catalysts to produce electricity [1].Most BFCs utilize the oxygen reduction reaction at the cathode, BFCs can be categorized by the type of catalyst used at the cathode: (I) metal catalysts, (II) enzymatic catalysts, and (III) microbial catalysts [2,3,4]
The construction of optimized biological fuel cells requires a cathode which combines the longevity of a microbial catalyst with the current density of an enzymatic catalyst [11,12]
Laccase-secreting fungi were grown directly on the cathode of a biological fuel cell constructed with a multifunctional cathode coating of titanium dioxide nanoparticles and carbon nanotubes
Summary
Biological fuel cells (BFCs) use bioderived fuels and catalysts to produce electricity [1].Most BFCs utilize the oxygen reduction reaction at the cathode, BFCs can be categorized by the type of catalyst used at the cathode: (I) metal catalysts, (II) enzymatic catalysts, and (III) microbial catalysts [2,3,4]. Biological fuel cells (BFCs) use bioderived fuels and catalysts to produce electricity [1]. Platinum-group metal catalysts are most common due to their superb catalytic properties, but the high price of the catalysts prevents the large-scale adoption of biological fuel cells [5]. Enzymatic catalysts hold promise to replace metal catalysts, but suffer from short lifetimes and mass transport limitations [3,4,6,7]. Microbial fuel cells rectify the short lifetimes of enzymatic catalysts at the expense of additional mass transport limitations and lower current densities [2,8,9,10]. The construction of optimized biological fuel cells requires a cathode which combines the longevity of a microbial catalyst with the current density of an enzymatic catalyst [11,12]
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