Gradient Carbon Nanotube/Nanofiber Electrodes for Ultra-Low Platinum Catalysts and Optimization of PEMFC Performance

摘要

Microstructure of catalyst layer in proton exchange membrane fuel cells (PEMFCs) is of great influence on the catalyst (Pt) utilization and cell performance. We demonstrated a functionally graded catalyst layer based on a double-layered carbon nanotube/nanofiber film (buckypaper) supported Pt composite catalyst to approach an idealized microstructure. The gradient distribution of Pt, electrolyte, and porosity along the thickness effectively depresses the transport resistance of proton and gas. A rated power of 0.88 W at 0.65 V was achieved at 80 °C with a low Pt loading of 0.11 mg/cm~2 resulting in a relatively high Pt utilization of 0.18 g_(Pt)/kW. The accelerated degradation test of catalyst support showed a good durability of buckypaper support because of high graphitization degree of carbon nanofibers.