Pore size and channel structure study of mesoporous SiO₂ films on sensing trace explosive

In this work, a new type of naphthalene dye was synthesized for detecting nitro explosives in solution and mesoporous film system. The fluorescence quenching mechanism between dye and explosive was determined. For detecting nitro explosives in gas system, mesoporous silica films doped with this fluorescent dye were successfully fabricated using the sol-gel technology with different templates. Two-dimensional hexagonal structure mesoporous silica film was found sensitive to traces of nitroaromatic trinitrotoluene. When enlarging the pore size, to improve the sensitivity, a lower sensitivity was actually obtained. This can be explained by the small molecule diameter of the explosive and the relatively large surface area of the mesoporous films. The Brunauer-Emmett-Teller surface area can be enlarged by a suitable 3D pore channel structure so that the fluorescence quenching sensitivity is improved for the nitro aromatic compounds vapors. Optimizing the pore size and channel structure can therefore well improve the sensing efficiency in this system.