A first principles and experimental study on the influence of nitrogen doping on the performance of amorphous carbon films for proton exchange membrane fuel cells

Abstract

Amorphous carbon (a-C) films exhibit promising application in the field of Proton Exchange Membrane Fuel Cells (PEMFCs) due to their unique properties and have been coated on the metallic bipolar plates (BPPs) of PEMFCs to improve the interfacial electrical conductivity and corrosion resistance of BPPs. However, a-C is still gradually oxidized in the harsh environments of PEMFCs and the performance of a-C needs to be further improved to achieve the lifetime target of PEMFCs. In this paper, nitrogen with different content is doped in a-C and the further understanding of corresponding mechanism on the structure and performance of a-C is revealed via first principles calculation and several experimental methods. The results indicate that doping nitrogen promotes the formation of stable CNx phase with better corrosion resistance and improves the compactness of the films. In addition, moderate content of nitrogen can improve the sp2 fraction of a-C. Furthermore, the film doped with about 10 at. % nitrogen exhibits excellent improvement of the electrical conductivity, corrosion resistance, durability and stability, especially the corrosion resistance under start-up/shut-down operating condition of PEMFCs. This study is beneficial to enhance the lifetime of a-C films and promote the commercialization of PEMFCs.