Surface Modifications of a Carbon Anode Catalyst by Control of Functional Groups for Vitamin C Fuel Cells

Abstract

We report that electro-oxidation treatment of carbon paper generates specific functional groups, and controllable coating of metal oxide films on carbon surface alters capacitive behaviors. Electrochemical characteristics, I-V curves in fuel cells, and a structural analysis of XPS represent that the carboxyl group is the most effective functional group in an electro-oxidation of L-ascorbic acid. The appropriate film thickness of titania on electro-oxidized carbon electrode further increases fuel cell performance and electrostatic capacitance by facilitating electron transfer reaction. An excessive amount of titania on carbon reduces contribution of carboxyl groups to electro-oxidation of L-ascorbic acid resulting in decline of catalytic effects since they prohibit L-ascorbic acid molecules from access to the adsorption sites on the carbon surface.

Positively charged carbon electrocatalyst for enhanced power performance of L-ascorbic acid fuel cells

“…The trend in activity for Vitamin-C electro-oxidation was expected to be similar to the capacitance trend, and this was found to be the case but with the exception of ATC-3. It has been shown previously that the surface oxygen intensity is important in improving electro-catalytic activity to the electro-oxidation of Vitamin-C [18,21,24] . However, ATC-3 was found to have a smaller O/C ratio than that of ATC-5, yet the electrocatalytic activities of both samples were similar.…”

“…The final criterion for the preparation of catalysts is their successful application as electrode materials in a fuel cell system with a zero-gap configuration [18] . Since this energy conversion system is considered as a potential energy source for implantable medical devices, testing was carried out at a temperature of 36.5 °C.…”

“…L-ascorbic acid (Vitamin-C) has been considered as a biologically friendly fuel, since the product of the electro-oxidation of L-ascorbic acid, dehydroascorbic acid (DHA), is reversely reduced to L-ascorbic acid inside the human body. L-ascorbic acid fuel cells can be a potential power source for human implantable devices [21,22] , but only a few studies have been reported [18,[20][21][22][23][24] . Fugiwara et al reported that the electro-oxidation of L-ascorbic acid using only carbon showed outstanding electro-catalytic ac-tivity [22,23] .…”

An Unprecedented CeO2/C Non-Noble Metal Electrocatalyst for Direct Ascorbic Acid Fuel Cells

“…In recent years, several AAOR electrocatalysts have been investigated, including noble metals [12,13], TiO 2 [14], polymers [2,15,16], porphyrins [17,18], and high-surface-area carbon black [11,19,20]. Our group previously reported that carbon black (BP2000) is the most effective AAOR electrocatalyst [11].…”