Disordered Mesoporous Zirconium (Hydr)oxides for Decomposition of Dimethyl Chlorophosphate

A facile method for the formation of mesoporosity within nonporous zirconium hydr(oxides) (ZrO₂/Zr(OH)₄) is presented and their detoxifying capabilities against dimethyl chlorophosphate (DMCP) are investigated. Nanoaggregates of ZrO₂/Zr(OH)₄ appear to be deposited on larger thin flakes of the same material. H₂O₂ is used to induce surface oxygen vacancies of synthesized ZrO₂/Zr(OH)₄ and, as a consequence, mesopores with an average diameter of 3.1 nm were formed. A surface area of H₂O₂-treated ZrO₂/Zr(OH)₄ was increased by an order of magnitude and shows enhanced reactivity toward DMCP. DRIFTS spectroscopy is employed to assess the reactivity differences between the H₂O₂-treated and untreated ZrO₂/Zr(OH)₄. Peaks at 1175 and 1144 cm^-1 indicate the presence of asymmetric stretching of the O-P-O moiety within dimethyl phosphonate (DMHP), a decomposition product from DMCP, and a zirconium-bound methoxy group, respectively. It is suggested that the decomposition of DMCP proceeds through the consumption of bridged hydroxyl groups (b-OH) for both the untreated and H₂O₂-treated samples, as well as an additional hydrolytic decomposition pathway for the H₂O₂-treated sample.