A novel cathode structure with double catalyst layers and low Pt loading for proton exchange membrane fuel cells

摘要

A novel cathode structure (NCS) was developed, which consisted of an inner and an outer catalyst layer (CL). It showed an improved platinum (Pt) utilization (above 50%), a lowered CL/gas diffusion layer interfacial resistance, and a decreased mass transport polarization compared with the traditional cathode structure (TCS). A hydrogen/air proton exchange membrane fuel cell employing NCS yielded an output power density up to 0.76 W cm~2 with cathode Pt loading as low as 0.28 mg cm~2. The enhanced performance of NCS is attributed to synergistic effect of the two catalyst supports in outer CL, which provides abundant pores to relieve water flooding and facilitates heat-induced proton conductor migration from the inner to outer CL, forming a hydrophilic proton conduction network. Moreover, the thin and compact inner CL can meet the demand of rich active sites and catalyst migration toward the regions nearest to the membrane under high current densities.