Unique spatial effect of Zr-doped ceria on the anti-free radicals and performance of PEMFC

During the operation of proton exchange membrane fuel cell, the functional groups in the ionomer are sensitive to free radicals, then lead to membrane degradation and cell failure. A common and effective approach is employing the radical scavengers-based material, which can reduce the content of reactive radical species followed by the improvement of proton exchange membrane and catalyst layer stability. However, few literatures pay attention to the effect of spatial on the initial electrochemical performance and chemical stability of fuel cells. Herein, Zr-doped ceria particles are synthesized and used as an additive on the cathode, anode or bilayer catalyst layers of the membrane electrode assembly. The results indicate that the addition of Zr-doped ceria particles to the cathode side will slightly increase the charge transfer and mass transfer resistance, then the initial polarization performance of membrane electrode assembly is reduced. But it can greatly improve the chemical stability of membrane electrode assembly (from 72 to 204 h during open circuit voltage test). • Reactive oxygen species are generated both on anode and cathode sides. • Cell failure is mainly caused by pinhole formation rather than membrane thinning. • Spraying CZO on cathode CL may be the best method to prepare high-performance MEA.