Performance characterization of direct formic acid fuel cell using porous carbon-supported palladium anode catalysts

Abstract

Palladium particles supported on porous carbon of 20 and 50 nm pore diameters were prepared and applied to the direct formic acid fuel cell (DFAFC). Four different anode catalysts with Pd loading of 30 and 50 wt% were synthesized by using impregnation method and the cell performance was investigated with changing experimental variables such as anode catalyst loading, formic acid concentration, operating temperature and oxidation gas. The BET surface areas of 20 nm, 30 wt% and 20 nm, 50 wt% Pd/porous carbon anode catalysts were 135 and 90 m²/g, respectively. The electro-oxidation of formic acid was examined in terms of cell power density. Based on the same amount of palladium loading with 1.2 or 2 mg/cm², the porous carbon-supported palladium catalysts showed higher cell performance than unsupported palladium catalysts. The 20 nm, 50 wt% Pd/porous carbon anode catalyst generated the highest maximum power density of 75.8 mW/cm² at 25 °C. Also, the Pd/porous carbon anode catalyst showed less deactivation at the high formic acid concentrations. When the formic acid concentration was increased from 3 to 9 M, the maximum power density was decreased from 75.8 to 40.7 mW/cm² at 25 °C. Due to the high activity of Pd/porous carbon catalyst, the cell operating temperature has less effect on DFAFC performance.