Microporous Layer Containing CeO2-Doped 3D Graphene Foam for Proton Exchange Membrane Fuel Cells at Varying Operating Conditions.

To improve the interfacial mass-transfer efficiency, microporous layers (MPLs) containing CeO2 nanorods and the CeO2 nano-network were prepared for proton exchange membrane fuel cells (PEMFCs). In order to minimize the contact resistance, the three-dimensional (3D) graphene foam (3D-GF) was used as the carrier for the deposition of CeO2 nanorods and the nano-network. The CeO2-doped 3D-GF anchored at the interface between the catalyst layer and microporous layer manufactured several novel functional protrusions. To evaluate the electrochemical property, the normal MPL, the MPL containing raw 3D-GF, and MPLs containing different kinds of CeO2-doped 3D-GF were used to assemble the membrane electrode assemblies (MEAs). Measurements show that the CeO2-doped 3D-GF improved the reaction kinetics of the cathode effectively. In addition, the hydrophilic CeO2-doped 3D-GF worked as the water receiver to prevent the dehydration of MEAs at dry operating condition. Besides, at a high current density or humid operating condition, the CeO2-doped 3D-GF provided the pathway for water removal. Compared with the CeO2 nanorods, the CeO2 nano-network on 3D-GF revealed a higher adaptability at varying operating conditions. Hence, such composition and structure design of MPL is a promising strategy for the optimization of high-performance PEMFCs.