Ultrathin nanoporous metal electrodes facilitate high proton conduction for low-Pt PEMFCs

Design of catalyst layers (CLs) with high proton conductivity in membrane electrode assemblies (MEAs) is an important issue for proton exchange membrane fuel cells (PEMFCs). Herein, an ultrathin catalyst layer was constructed based on Pt-decorated nanoporous gold (NPG-Pt) with sub-Debye-length thickness for proton transfer. In the absence of ionomer incorporation in the CLs, these integrated carbon-free electrodes can deliver maximum mass-specific power density of 198.21 and 25.91 kW·g_Pt^-1 when serving individually as the anode and cathode, at a Pt loading of 5.6 and 22.0 μg·cm^-2, respectively, comparable to the best reported nano-catalysts for PEMFCs. In-depth quantitative experimental measurements and finite-element analyses indicate that improved proton conduction plays a critical role in activation, ohmic and mass transfer polarizations.