Efficient catalyst layer with ultra-low Pt loading for proton exchange membrane fuel cell

Developing rational structure of catalyst layer with high stability and efficient mass transport to maximize the utilization of Pt is critical to fabricate proton exchange membrane fuel cells (PEMFCs) with ultra-low Pt loading down to <100 & mu;g cm- 2. Herein, a newly designed catalyst layer with ultra-low Pt loading for PEMFC was developed using a three-dimensional graphene network (3D-GN). In the process, 3D-GN was directly grown onto an Al foil by arc discharge method, and then Pt nanoparticles were deposited by via electron beam evaporation, after the impregnation of Nafion solution and non-destructive transfer onto Nafion membrane, the electrode with Pt/3D-GN was finally fabricated. The 3D-GN possesses unique characteristics of self-supporting structure of graphene nanosheets with 3-7 layers of graphitic lattices, a high macro-porous pore volume of 19.93 mL g-1 and graphitic degree up to 74.9 %, which can provide a stable framework to support Pt nanoparticles and efficient mass transport pathways. The Pt/3D-GN as the cathode can achieve a high cell performance at ultra-low Pt loading, compared to the conventional carbon nanosphere-based electrode (CN). The maximum power density of Pt/3D-GN with 50.8 & mu;gPt cm-2 is 1.31 W cm-2 (H2/O2, 150 kPa) and 0.64 W cm-2 (H2/Air, 150 kPa), higher than that of commercial Pt/C electrode with 100 & mu;gPt cm-2 1.25 W cm- 2 and 0.55 W cm-2 respectively. Meanwhile, the Pt/3D-GN also demonstrates excellent stability with 32 % lose after 30 k cycles (0.6 V and 0.95 V) and only 8 % decay after 5 k cycles (1.0 V-1.5 V vs RHE). The outstanding properties of 3D GN-based electrode with high activity and stability provides a new flexible platform for developing high-performance ultra-low Pt loading PEMFCs.