Synthesis Of Silicon-containing Substituted Heteropoly Acids And HPAs/Graphene/Organic Matrix Hybrid Film

Heteropoly acids (HPAs) are a kind of polynuclear coordination compounds which contain oxygen bridge. They are one of the most promising and widely-used functional materials. The synthesis of novel HPAs and the preparation of HPAs-based hybrid materials have become one of the research focuses in the area of HPAs chemistry.Two novel silicon-containing substituted heteropoly acids H6SiW9MoV2O40·15H2O (SiW9MoV2) and H6SiWioV2O40·14H2O (SiW10V2) were synthesized by the stepwise acidification, the stepwise addition of elemental solutions as well as ether extraction method. Their composition, structure and thermal stability were characterized by ICP-MS, IR, UV, XRD and TG-DTA. Their proton conductivities are 6.01×10-3 S·cm-1 (SiW9MoV2) and 7.40×10-3 S·cm-1(SiW10V2) at ambient condition. They are novel high proton conductors. The activation energies for their proton conduction are 27.50 KJ·mol-1 and 21.02 kJ·mol-1, respectively, indicating the proton conductive mechanism for these compounds is Vehicle mechanism.We have chosen phosphorus-containing heteropoly acids, H4PW11VO40 (PW11V) and H6PW9V3O40 (PW9V3), and SiW9MoV2, SiWi0V2 to synthesize HPAs/rGO composites. Furthermore, we chose sulfonated polyether ether ketone (SPEEK) as the organic matrix to prepare HPAs/rGO/SPEEK hybrid film materials: PW11V/rGO/SPEEK, PW9V3/rGO/SPEEK, SiW9MoV2/rGO/SPEEK and SiW10V2/rGO/SPEEK. These film materials were characterized by IR., TEM and XRD. The results show Keggin framework of heteropolyanions still remains in these hybrid materials, and graphene is an excellent carrier to load HPAs, which could immobilize HPAs and results in a better stability of HPAs. The result shows that proton conductivity of these film materials all reach 10-2 S·cm-1 at ambient condition. It is the mixing mechanism that accelerates the proton conduction in these hybrid films.