(654b) A Combined Theoretical and Experimental Investigation on the Degradation of Organophosphorus Chemical Warfare Agents on ZnO1-X

Metal oxide nanoparticles (MONP) have long been known to act as reactive sorbents for the degradation of chemical warfare agents (CWA). However, contrary to nature, which is capable of producing enzymes that can detoxify the same CWA at ambient conditions, MONP are stoichiometric and require elevated temperatures in order to remove the products from the surface. Herein vacancy induced MONP are examined for the degradation of organophosphorus agents by both experimental and theoretical means. Oxygen vacancies are introduced into MONP of zinc oxide (ZnO_1-X) and characterized by Raman spectroscopy, x-ray photospectroscopy (XPS), UV-vis spectroscopy, transmission electron microscopy (TEM) and x-ray diffraction (XRD). The reactivity of ZnO_1-X is evaluated using diisopropyl fluorophosphate (DFP) with solid state NMR, indicating that the vacancy induce structures exhibit a 25% increase in reactivity compared to the parent MONP. In parallel, a detailed mechanistic study revealing the path of degradation is investigated utilizing plane-wave density functional theory (DFT). Comparative studies are performed evaluating the stability of an oxygen vacancy on either the 002 or 100 surface planes of zinc oxide, as well as in the bulk and surface, revealing the latter to be the most stable. Binding energies were calculated using phosphine as a surrogate molecule to represent the surface reaction between ZnO_1-X and organophosphorus CWAâ??s. The results obtained here not only provide a mechanistic insight towards CWA degradation, but will aid in the future development of more efficient catalyst against CWAâ??s.