Self-Assembly Of Functional Fullerene Derivatives And Their Applications In Fuel Cells

Fullerene (C60) and its derivatives have attracted much attention since discovery in1985, due to their excellent optoelectronic performance. Fuel cells have been considered to be one of the most important high-teches that will have great impact on human’s life in the21st century, making the development of efficient electrocatalysts a hot issue. It has been known that the complex supramolecular architectures can be fabricated from fullerenes via controlled self-assembly, and the high surface areas are desired for catalyst supports in fuel cells. However, little attention was paid to the potential application of complex fullerene architectures with high surface areas in fuel cells. In this dissertation, self-organized flowerlike architectures of C60derivatives were constructed and their potential applications in fuel cells were also investigated.Firstly, a series of C60derivatives containing small functional substituents (such as carboxyl, ester and nitro) were synthesized and characterized. The self-assembly behaviors of these derivatives under different experimental conditions (solvent, substrate, atmosphere and temperature, etc.) were studied systematically. It was found that the property of solvent and the position of functional groups affect the self-assembly in some extent, while substrate is not one of the most important factor influencing the morphology of organized structures. Almost all of these C60derivatives can get complex morphology with large specific surface area by optimizing the experimental conditions. The XRD analysis indicates that the assembled objects may be organized from a bilayer unit where the C60molecules arranged in a zigzag type fashion. Moreover, the substituent effect on electrochemical properties, optical properties, and the molecular orbital energy level were also investigated by using CV, absorption and fluorescence spectroscopies, and DFT calculations, respectively. The results showed that while the substitution has little effect on redox behaviors or photophysical properties, a significant raise of LUMO energy level was observed on ortho-nitrophenyl derivative, which was attributed to the through-space orbital interaction between spatially closed electron-withdrawing nitro group and fullerene cage.Secondly, the application of the self-assembled structures of these C60derivatives as catalyst carrier in fuel cells was discussed. The composite catalysts, prepared by electrochemical deposition of Pt or Pd nanoparticles on ITO electrodes covered by the self-organized objects of C60derivatives, exhibited a remarkably enhanced activity in methanol oxidation. In addition, one kind of novel hollow core-shell M@Pt or M@Pd (M is Co, Ni, or Co-Ni alloy) catalysts loaded on multi-walled carbon nanotubes was designed and prepared, which showed an excellent catalytic activity in direct methanol fuel cells.