Development of Nitrogen-Modified Carbon-Based Catalysts for Oxygen Reduction in PEM Fuel Cells

摘要

Carbon-based catalysts for oxygen reduction reaction (ORR) were synthesized by modifying the carbon surface with nitrogen-containing precursors. The electrocatalytic properties were studied as a function of surface treatment, nitrogen and oxygen concentrations, and heat-treatment temperature. The catalysts showed an onset potential for ORR close to 0.83 V and the amount of H_2O_2 generated was about 1 % at 0.5 V under our experimental conditions. The current transient in fuel cell at 0.4 V exhibited an initial increase of current density to approximately 0.12 A cm~(-2) and then a steady-state current profile for up to 200 h. The characterizations indicated that pyridinic and graphitic nitrogen acts as catalytic sites for ORR.