Electrochemical behaviors and redox properties of polyoxometalate (POM)/SBA-15 mesoporous hybrid materials, prepared by co-condensation and post-synthesis, were investigated using carbon paste electrodes by cyclic voltammetric measurement. In acetonitrile solution and the range of potentials studied, the cyclic voltammograms of free species in the solution and the same species loaded on mesoporous silica by impregnation showed two one-electron waves corresponding to redox processes of W^VI. For the same POM species bonded covalently onto mesoporous silica, however, the current of first wave increased and reduction potentials shifted towards positive direction as compared with the impregnated sample, indicating that these species not only retained the redox property of POM perfectly, but also possessed more intense oxidbillity than the impregnated POM species. The plots of current versus scan rate showed that the redox processes of the hybrid samples were surface-controlled at lower scan rates but diffusion-controlled at higher scan rates. It was also found that the oxidbillity of tungstophosphate was higher than that of tungstosilicate; and the similar electrochemical behaviors were presented for the hybrid samples prepared by both routes.

Key words: electrochemical property, cyclic voltammetry, polyoxometalate, SBA-15, mesoporous hybrid materials