The influence of Bi Modification of Pt anode catalyst in direct formic acid fuel cells

초록

Small organic molecules such as formate, formaldehyde and formic acid have potential as possible fuels in direct small organic fuel cells and are also involved as intermediates produced during the dehydrogenation of methanol. Of late, Masel et al. presented that a formic acid fuel cell (DFAFC) has a higher power density compared with DMFC due to its lower fuel crossover flux, faster kinetics in the electro-oxidation and higher theoretical equilibrium potential calculated from Gibbs free energy. Up to now, many noble metals and/or alloys as an anode catalyst in the DFAFC have been evaluated and each one has distinct activity in DFAFC. 5B materials in periodic table, arsenic (As), antimony (Sb) and bismuth (Bi) have been used as modifier of Pt anode for the better formic acid oxidation. In particular, Bi could enhance the electrocatalytic activity and hinder the adsorption of poisoning intermediate species, CO via third-body and electronic effect. Thus, applying same outer potential, oxidation current on a Bi modified Pt is about 5 ~ 60 times higher than that of pure Pt electrode. This research forced on the activity and durability of Bi-modified Pt anode in the operation of direct formic acid fuel cells. Cyclic voltammetry, chronoamperometry, current-potential polarization measurements and long-term operation at a constant current loading were tools of choice. Bi-Pt anode had about 50 % higher power output compared with pure Pt anode and it was explained by the understanding of the experimental observations of