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Corresponding Author

Min-hua SHAO(kemshao@ust.hk)

Abstract

The commercialization of proton exchange membrane fuel cells (PEMFCs) is hindered by high cost and low durability of Pt based electrocatalysts. Developing efficient and durable non-precious metal catalysts is a promising approach to addressing these conundrums. Among them, transition metals dispersed in a nitrogen (N)-doped carbon support (M-N-C) show good oxygen reduction reaction activity. This article reviews recent progress in M-N-C catalysts development, focusing on the catalysts design, membrane electrode assembly fabrication, fuel cell performance, and durability testing. Template-assisted approach is an efficient way to synthesize M-N-C materials with homogeneously dispersed single atom active site and reduced metal particles, carbides formation. However, the issue related to low intensity of active sites should be addressed via strengthening metal-ligand interaction and using high surface area precursors. In general, the catalyst loading for the membrane electrode assembly (MEA) of non-precious catalyst is high (3 ~ 4 mg·cm-2) in order to obtain acceptable performance, which is also highly dependent on ink preparation and coating protocol, ionomer/catalyst ratio, etc. The highest power densities for Fe-N-C and Co-N-C are reported to be 1.18 and 0.87 W·cm-2 with O2 at the cathode, respectively. Despite the significant progress in non-precious metal catalysts development, the undesired durability (only a few hundreds of hours) is still far from the target of 5000 h by 2025. Thus, much more efforts should be spent on improving their durability.

Graphical Abstract

Keywords

proton exchange membrane fuel cells, non-precious metal catalysts, membrane electrode assembly, durability

Publication Date

2020-08-28

Online Available Date

2020-05-20

Revised Date

2020-05-08

Received Date

2020-03-14

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