Fluoroaromatic substituents attached to carbon nanotubes help to increase oxygen concentration on biocathode in biosensors and biofuel cells

Abstract

Based on the known ability of perfluorodecalin/perfluorohydrocarbons to enhance oxygen solubility we modified oxygen sensitive biocathode by adding perfluorinated components to the catholite. This procedure improved the efficiency of the oxygen sensitive cathodes. Glassy carbon electrodes covered with single-wall carbon nanotubes (SWCNTs) with covalently bonded perfluoroaromatic groups were shown to be more sensitive to oxygen, and higher catalytic reduction currents were observed using laccase modified biocathodes allowing to improve the performance of bioelectrodes for fuel cells and oxygen monitoring devices. Maximum current and power density was found for the glucose/oxygen fuel cell composed of anode modified with side-aminoethylated SWCNTs conjugated with glucose dehydrogenase and cathode covered with side-perfluorophenylated SWCNTs and laccase. The open circuit potential of this cell is 0.57±0.05V and the maximum power density is 0.865±0.090mW/cm2. In case of applications of biofuel cells in the biological media, in order to avoid addition of NAD+ to the solution, we propose binding this cofactor to the aminoethylated SWCNTs. For applications of this biofuel cell in biological media, we propose binding NAD+ cofactor to the aminoethylated SWCNTs instead of its addition to the electrolyte. The power output 0.226±0.031mW/cm2 of such cell is somewhat smaller but still satisfactory, and the open circuit potential is 0.65±0.08V.