The Preparation And Photoelectrochemical Properties Of Higher Fullerene Micro/Nano Structures

Higher fullerenes have many unique physical, chemical and biomedical properties. It is well acknowledged that the assembly of fullerenes into well-defined nanostructures can greatly help to improve or modulate their properties, which will fundamentally facilitate their application in various fields. In this dissertation, we focused on the controlled synthesis of higher fullerene nanostructures using the liquid-liquid interfacial precipitation?LLIP? method. The higher fullerenes used here are C₇₆, C₇₈, C₈₂, C₈₄, C₇₆/C₇₈ mixture(C₇₆/C₇₈?m/m? = 2:3) and C₈₂/C₈₄ mixture(C₈₂/C₈₄?m/m? = 4:21). Then the crystal structures and photoelectrochemical properties of the well-defined nanostructures were carefully studied. The results are summarized as follows:?1? We used the direct current arc-discharged method and high performance liquid chromatography?HPLC? for preparation, separation and purification of C₇₆, C₇₈, C₈₂, C₈₄, C₇₆/C₇₈ and C₈₂/C₈₄. Our results show that the cage structures of C₇₆, C₇₈, C₈₂ and C₈₄ are quite different, but they tend to form similar micro/nano morphologies using the same solvent/antisolvent systems, which strongly prove that the solvent condition is the key factor for the assembly of fullerenes. Moreover, the following four kinds of fullerene nanostructures have been successfully prepared: C₈₄ microrods and microsheets from CS2/isopropanol?IPA? system(C₈₄-CS2), C₈₄ nanorods from toluene/IPA system(C₈₄-T), C₈₄ pyramids from TMB/IPA system(C₈₄-TMB), C₈₂/C₈₄ nanorods from toluene/IPA system(C₈₂-C₈₄-T).?2? The crystal structures and photoelectrochemical properties of the following four kinds of fullerene nanostructures were studied: C₈₄-CS2, C₈₄-T, C₈₄-TMB, C₈₂-C₈₄-T. The crystal structures were investigated by XRD and TEM measurements. Accordingly, C₈₄-CS2 is a mixture of cubic and orthorhombic phases. C₈₄-T has the cubic structure, C₈₄-TMB pyramids are possessed with hexagonal phase, C₈₂-C₈₄-T nanorods are both cubic structures. Moreover, UV-vis-NIR results evidently reveal that all these C₈₄ nanostructures display much broader and stronger absorptions than that of the C₈₄ toluene solution both in the visible and near-infrared regions. Similarly, the C₈₂-C₈₄-T nanorods show much broader and stronger absorption in the visible and near-intrared regions than that of the C₈₂/C₈₄ toluene solution. The photocurrent tests were conducted using a three-electrode system. The results reveal the different photoelectrochemical properties of micro/nano structure, leading to the finding that the rod is advantageous for charge transfer. Our results give clear evidence that the assembly of fullerenes well-defined nanostructures can substantially improve their photoelectrochemical properties, which will further promote their practical applications in optoelectronics.