Proton Conduction in Polyhydroxy Hydrogensulfated Fullerenes

Abstract

Proton conductivity of polyhydroxy hydrogensulfated fullerene C60(OSO3H)x(OH)yC60(OSO3H)x(OH)y (x∼6,y∼6),(x∼6,y∼6), and partially hydrolyzed polycyclosulfated fullerene, C60(OSO2O)6­z(OSO3H)z(OH)zC60(OSO2O)6­z(OSO3H)z(OH)z (z<1),(zOSO3H,OSO3H, surrounding the fullerene cage leads to higher conductivity. The activation energy of the conduction in C60(OSO3H)x(OH)yC60(OSO3H)x(OH)y was estimated to be 0.35 eV from a variable-temperature conductivity measurement. The conductivity is constant for 15 h in a dry-gas condition, indicating that no water molecule drifts together with a proton in this material. It is thus suggested that protons in a polyhydroxy hydrogensulfated fullerene are transported by a hopping mechanism as is the case for fullerenol C60(OH)12.C60(OH)12. © 2002 The Electrochemical Society. All rights reserved.