Nano-composite of phosphoric acid derivative of fullerene with SiO2 and its proton conductivity

The nano-composite of the phosphoric acid derivative of fullerene ([PO(OH)(2)](2)CC60) with SiO2 was synthesized using the in-situ reaction from [PO(OH)(2)](2)CC60 with tetraethoxysilane (TEOS). The nano-composite was characterized using FT-IR measurements, and its morphology was observed using SEM. The humidity dependence of their proton conductivity for both [PO(OH)(2)](2)CC60 and its nano-composite was investigated. The proton conductivity of the nano-composite is increased more than one order of magnitude higher than that of [PO(OH)(2)](2)CC60 under low relative humidity. This is probably because the more proton conductive sites are generated by SiO2. However its proton conductivity is lower in the humidity range above 60%, probably because the number of the highly dissociative protons from phosphoric acid is decreased after being combined with silica.