Nickel catalyst migration in an anion exchange membrane fuel cell

Nickel materials have been widely studied as non-platinum group metal (non-PGM) cathode catalysts for anion exchange membrane fuel cells (AEMFC). Although the stability of Ni based catalysts has been tested by accelerated potential cycling, this analysis does not fully simulate the operating AEMFC conditions. For back-up power systems, the standby AEMFCs need to be held at a high steady state cell potential. For cathode catalysts, this may be more challenging than cycled potentials. As Ni dissolution has been reported from Ni and Ni alloyed catalysts under cycled cathode potentials, its stability under steady state potentials should be questioned. In this study, a Ni on Vulcan® XC72 carbon (Ni/C) was tested at the cathode of a simulated AEMFC, under a 0.9 V steady state cell potential for 1500 h. After operation, in addition to Ni oxidation at the cathode, Ni dissolution and migration was found resulting in cathode catalyst morphology changes and Ni(OH)2 deposits on the anode. These results were supported by scanning electron microscopy (SEM), scanning transmission electron microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) analyses.