Fe-N-C catalysts for PEMFC: Progress towards the commercial application under DOE reference

Proton exchange membrane fuel cells (PEMFC) have attracted much attention because of their high energy conversion efficiency, high power density and zero emission of pollutants. However, the high cost of the cathode platinum group metal (PGM) catalysts creates a barrier for the large-scale application of PEMFC. Tremendous efforts have been devoted to the development of low-cost PGM-free catalysts, especially the Fe-N-C catalysts, to replace the expensive PGM catalysts. However, the characterization methods and evaluation standards of the catalysts varies, which is not conducive to the comparison of PGM-free catalysts. U.S. Department of energy (DOE) is the only authority that specifies the testing standards and activity targets for PGM-free catalysts. In this review, the major breakthroughs of Fe-N-C catalysts are outlined with the reference of DOE standards and targets. The preparation and characteristics of these highly active Fe-N-C catalysts are briefly introduced. Moreover, the efforts on improving the mass transfer and the durability issue of Fe-N-C fuel cell are discussed. Finally, the prospective directions concerning the comprehensive evaluation of the Fe-N-C catalysts are proposed.