Abstract
Highly-dispersed palladium-based electro-catalysts on a conductive carbon support are ordinarily utilized as anode materials in low-temperature direct alcohol fuel cells. The activity and stability of these electro-catalysts firmly rely upon the attributes of the carbon support material. This study focused on monometallic Pd and binary Pd-Ru electro-catalysts supported on functionalized carbon nanofibers using alcohol reduction method. Carbon nanofibers (CNFs) were successfully prepared employing a chemical vapor deposition method using chicken oil as a starting material. The unique worm-like morphology made the material very interesting as carbon support for fuel cell electro-catalysts.
The synthesized nanomaterials were studied using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Transmission electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The FTIR results confirmed that the prepared carbon nanofibers are functionalized with carboxylic acid functional groups which facilitate the dispersion of metal nanoparticles. The Raman spectrum revealed that the synthesized CNFs contains two peaks D and G bands, which correspond to a disordered carbon peak (D) and graphite peak (G). The morphology, shape and particle distribution were confirmed using TEM. The micrographs showed that Pd and Pd-Ru nanoparticles were successfully attached onto the functionalized carbon nanofibers. The metal loading and the presence of Pd, Ru, C and O elements for the synthesized electro-catalyst was examined using SEM/EDS. XRD peaks confirmed that the carbon nanofibers were amorphous and Pd (111), (200), (220) and (222) facets were observed on the surface layers of Pd/CNFs and Pd-Ru/CNFs electro-catalysts. XPS results showed the composition of the prepared samples and oxidation states of Pd and Ru of the synthesized electro-catalysts.
The electro-catalytic behavior of the Pd/CNFs catalyst was tested towards the ethanol and methanol electro-oxidation in alkaline media to assess the performance of the CNFs support material against the commercial Pd/C electro-catalyst. Cyclic voltammetry (CV) and chronoamperometry (CA) results showed that the Pd/CNFs electro-catalyst prepared by alcohol reduction method exhibit superior performance as compared to the commercial Pd/C electro-catalyst for both ethanol and methanol electro-oxidation in alkaline media...
M.Tech. (Chemistry)