High-Performance Polymer Electrolyte Membrane Fuel Cells Based on Fe/N/C ORR Catalyst

Abstract

One of the barriers hindering the commercialization of polymer electrolyte membrane fuel cell (PEMFC) is the high cost, in large part due to the expensive Pt-based catalyst for both the cathodic oxygen reduction reaction (ORR) and anodic hydrogen oxidation. The ORR requires more Pt catalyst than anodic hydrogen oxidation because of the sluggish kinetics. Therefore, ternary Fe/N/C material, as a non-Pt catalyst for ORR, is being studied intensively as one of the most promising alternatives for expensive Pt-based catalysts. However, the catalytic activity of Fe/N/C materials is considerably inferior to that of Pt-based catalyst in acidic medium. What’s more, the stability of Fe/N/C is poor and the decay mechanism remains unclear. Here, we found that iron salts can also greatly influence the ORR activity of Fe/N/C, and the use of Fe(SCN)3 instead of FeCl3 can nearly double the ORR activity. The improvement may be correlated with S doping and high surface area. The Pmax of PEMFC using this improved catalyst reached 0.94 and 1.03 Wcm-2 at 1 and 2 bar back-pressure, respectively. Moreover, we find that oxidized environment in PEMFC, mainly caused by oxygen, high voltage and hydrogen peroxide, can deteriorate Fe/N/C catalyst. Figure 1