Carbon Nanofibers “Spot-Welded” to Carbon Paper by Carbothermal Reduction: A Nano/Micron-Scale Hierarchical Architecture having Low Contact Resistance

The synthesis, characterization, and electrical measurements of graphitic carbon nanofiber (GCNF)/carbon paper composite materials are reported. GCNF/carbon paper composites having relatively weak GCNF/carbon paper and GCNF/SiO2/carbon paper interfacial binding are prepared by growing carbon nanofibers directly from growth catalyst nanoparticles distributed throughout the carbon paper support. Carbothermal reduction of GCNF/SiO2/carbon paper composites effectively “spot welds” carbon nanofibers to carbon paper fibers affording mechanically robust GCNF/SiC/carbon paper composite materials. Characterization methods include scanning electron microscopic imaging, chemical composition and elemental mapping by energy-dispersive X-ray spectroscopy, X-ray diffraction and Raman spectroscopy for phase identification, BET surface-area analysis, and measurement of in-plane and contact electrical resistance. Plots of the pressure dependence of the contact resistance of GCNF/carbon paper and GCNF/SiC/carbon paper composites fall between those of commercial plain carbon paper and wet-proofed carbon paper with the GCNF/SiC/carbon paper composite having a contact resistance similar to that of plain carbon paper. A method for instilling a nano/microscale hierarchical architecture to carbon paper without incurring significant increase of contact resistance is reported.