Zirconia-Based Aerogels for Sorption and Degradation of Dimethyl Methylphosphonate

Inspired by recent breakthroughs with Zr(OH)(4)-type materials that decompose chemical warfare agents (CWAs), we explore aerogel forms of zirconium oxyhydroxide (ZrOxHy) as reactive sorbents for dimethyl methylphosphonate (DMMP), a common simulant for organo-phosphorous CWAs. Zirconia gels were synthesized using propylene oxide and aqueous ZrCl4, followed by supercritical-CO2 extraction to yield monolithic ZrOxHy aerogels. Subsequent calcination at temperatures >= 350 degrees C removes organic byproducts of the epoxide-based synthesis while preserving high specific surface area (up to 234 m(2) g(-1)) and the aerogel-like, cocontinuous pore-solid structure. Infrared (IR) spectroscopy and H-1 nuclear magnetic resonance spectroscopy confirm that ZrOxHy aerogels retain a high concentration of surface hydroxyls, even when heated to 600 degrees C and converted to nanocrystalline cubic/monoclinic ZrO2. We used in situ IR spectroscopy to probe the interactions of DMMP with a series of ZrOxHy aerogel powders, showing that DMMP rapidly decomposes by reacting with the hydroxyl-rich aerogel to form surface-bound Zr-OCH3 and bridging O-P-O species. We compare these results to those of related zirconia-type materials and discuss prospects and advantages of ZrOxHy aerogels for CWA mitigation.