Nonordered porous silica-based pure inorganic and hybrid organic-inorganic materials prepared by a nonaqueous, nonthermal sol-gel process

Abstract

Abstract Herein is reported the synthesis and characterization of nonordered porous silica-based materials, University of Guanajuato Materials (UGM), which were obtained from a mixture of alkoxysilanes by using a nonaqueous, nonthermal sol-gel methodology without the addition of any directing agent and using wet acetone (1% water content) as a hydrolytic agent. The textural properties of specific surface area, pore volume and pore size were determined by means of N2 physisorption at 77 K. The UGM silicas are described to be microporous, mesoporous and mixture of micro/mesoporous materials that may have Brunauer-Emmett-Teller (BET) surface areas of up to 300 and 600 m2/g, respectively. Some of these materials were organofunctionalized by a co-condensation route. On the one hand, the silica UGM-111-OP(OH)2 corresponds to a nonordered mixture of micro and mesoporous material with a surface area of 500 m2/g, and a Nafion®-[UGM-111-OP(OH)2] composite membrane was electrochemically characterized by cyclic voltammetry; the results indicated that the composite has promising potential for use as a proton-conductive material in proton-exchange membrane (PEM)-type fuel cells. On the other hand, the UGM-111-triamine silica is a mesoporous material with monomodal porosity (average pore diameter 3.75 nm) and a BET surface area of 570 m2/g; this material may have potential applications in the adsorption of metal ions such as copper (II). All materials were characterized in the solid state by 13C and 29Si CP-MAS, and UGM-111-OP(OH)2 was also characterized by 31P CP-MAS. Scanning electron microscopy (SEM) at 15000X magnification showed that both pure and hybrid organic-inorganic UGM silicas may be present as agglomerated spheres and that mesoporous pure UGM silicas may appear as nonuniform granular powders.