Département de chimie moléculaire

We report the functionalization of multi-walled carbon nanotubes (MWCNTs) electrodes by a bifunctional nitroarom. mol. accomplished via $π$-$π$ interactions of a pyrene deriv. DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) has the particularity to possess both electroactivable nitro groups and neg. charged carboxylic groups. The integration of the DTNB-modified MWCNTs was evaluated for different bioelectrocatalytic systems. The immobilized DTNB-based electrodes showed electrocatalytic activity toward the oxidn. of the reduced form of NAD (NADH) with low overpotential of -0.09 V vs Ag/AgCl at neutral pH. Glucose dehydrogenase was successfully immobilized at the surface of DTNB-based electrodes and, in the presence of NAD+, the resulting bioelectrode achieved efficient glucose oxidn. with high current densities of 2.03 mA cm-2. On the other hand, the arom. structure and the neg. charged nature of the DTNB provoked orientation of both laccase and bilirubin oxidase onto the electrode, which enhanced their ability to undergo a direct electron transfer for oxygen redn. Due to the proper orientation, low overpotentials were obtained (ca. 0.6 V vs Ag/AgCl) and high electrocatalytic currents of about 3.5 mA cm-2 were recorded at neutral pH in O2 satd. conditions for bilirubin oxidase electrodes. The combination of these bioanodes and bilirubin oxidase biocathodes provided glucose/O2 enzymic biofuel cells (EBFC) exhibiting an open-circuit potential of 0.640 V, with an assocd. max. c.d. of 2.10 mA cm-2. Moreover, the fuel cell delivered a max. power d. of 0.50 mW cm-2 at 0.36 V. [on SciFinder(R)]