Impacts of meso-structure and organic loadings of fluoroalcohol derivatives/SBA-15 hybrids on nerve agent simulant sensing

This paper employed a measurement of quartz crystal microbalance (QCM) to investigate the effects of mesopore structures and amount of organic loadings of fluoroalcohol derivatives/SBA-15 (a kind of ordered mesoporous silica sieve) hybrids on the sensing behavior of nerve agent simulant DMMP (dimethyl methylphosphonate). The meso-structure and functional groups of silica-based mesoporous hybrids were examined by SAXS, TEM, N2 adsorption-desorption isotherms and elemental analysis. The results show that much higher response value and sensitivity are achieved when the hybrid materials have relative higher pore volume and surface area. However, this effect only appears when the mesoporous hybrids have well-ordered porous structure, indicating that ordered meso-structure is critical in fabricating high-performance DMMP sensors. The reason is likely that the ordered meso-structure not only provides a larger number of contactable HFIP groups, but also facilitates molecules diffusion in porous structure. On the other hand, the specific interaction between HFIP/SBA-15 hybrids and DMMP vapor is greatly enhanced as the amount of fluoroalcohol derivatives increases. Therefore, the amount of organic functional groups incorporated plays an important role in determining the selectivity of sensors.