(487g) Pt-Catalyzed Self-Grown Branched Carbon Nanofibers and Its Applications to Electrode Materials

CNFs/CNTs are very attractive materials in various fields of research due to the outstanding mechanical strength, electric conductivity, large surface area, and high aspect ratio. For the utilization of carbon nano structures as catalyst supports, a variety of studies have been focused on the formation of branched CNT using catalytic vapor deposition, where Fe, Co, Ni series were used as catalysts to form branches from the carbon source gases. In the present study, branched carbon nanofibers (b-CNFs) were fabricated from the electro-spun carbon stem fibers without external supply of carbon sources. A transition from fibrous structure of the stem to tubular shape generated carbon sources, which subsequently were converted to the b-CNFs through reaction catalyzed by co-spun Pt particles on the stem. The experimental procedures are composed of 1) preparation of composite fibrous polymer sheet by electrospinning of hexachloroplatinum, poly vinylidiene fluoride (PVdF), N,N-Dimethylacetamide (DMAc) and 1,8-Diazabicyclo [5.4.0]-undec-7-ene (DBU) solutions using capillary tip and high voltage, 2) dehydrofluorination of resulting fibrous polymer sheet using NaOH, and the last step of 3) carbonization at high temperature (~800oC) N2 atmosphere to change the resulting fibrous stem into nanotubes. During the last step, the spurted out carbon sources from the fibers formed sub-100 nm thick b-CNF (Fig. 1) by 3~4 nm Pt particles that were generated during the carbonization step. The morphologies, structures, effective surface area, crystallinity, and other properties of CNFs/CNTs were characterized by SEM, HRTEM, Raman spectroscopy, and N2 physisorption. The results indicated smooth surfaces of the CNFs/CNTs. As shown in Fig. 2, the ratios of IG/ID of the CNF and the CNT are 1.01 and 1.09, respectively and the surface area of CNFs/CNTs analyzed by N2 physisorption is about 470 m2/g. The electrocatalytic activity of Pt nanoparticles imbedded in the carbon nanostructures and the possibility of utilization of b-CNF as catalyst supports will be discussed.