| Abstract
| - Mesoporous Ta oxide is reduced with 1 equiv of Li-naphthalene. Impregnation of this alkylated mesostructure with C60 leads to partial electron transfer from the walls to the fullerene phase. This allows for electrochemical studies of Li insertion and deinsertion into the mesostructure.
- A mesoporous tantalum oxide lithium fulleride composite was synthesized by solutionintercalation of C60 into a prefabricated Li-TaTMS material and characterized by elementalanalysis, X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption−desorption,X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device(SQUID) magnetometry, and solid-state 13C and 7Li NMR. The room conductivity measurements of Li fulleride material showed that this material was insulating, as opposed topreviously synthesized K and Na based mesoporous Ta oxide fulleride composites with similarcomposition, which were semiconducting or metallic. Solid-state 7Li NMR of this lithiumcomposite exhibited a single Li environment. XPS measurements indicated an oxidation ofthe tantalum oxide walls had occurred upon intercalation of the fullerene 13C NMR, andRaman measurements were consistent with one fulleride species in the pores. Electrochemicalmeasurements revealed largely irreversible behavior upon intercalation/deintercalation ofLi+ into this material. This was attributed to the insulating nature of this composite impedingcharge transport through the channels. In contrast, the corresponding Na fulleride intercalateshowed reversible Li insertion, possibly due to enhanced charge transport through thesemiconducting structure.
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