| AVS 64th International Symposium & Exhibition | |
| Surface Science Division | Tuesday Sessions |
| Session SS+HC-TuM |
| Session: | Controlling Mechanisms of Surface Chemical Reactions |
| Presenter: | Lena Trotochaud, Lawrence Berkeley National Laboratory |
| Authors: | L. Trotochaud, Lawrence Berkeley National Laboratory R. Tsyshevsky, University of Maryland, College Park S. Holdren, University of Maryland, College Park K.P. Fears, U.S. Naval Research Laboratory A.R. Head, Lawrence Berkeley National Laboratory Y. Yu, University of Maryland, College Park O. Karslioglu, Lawrence Berkeley National Laboratory S. Pletincx, Vrije Universiteit Brussel, Belgium B. Eichhorn, University of Maryland, College Park J. Owrutsky, U.S. Naval Research Laboratory J. Long, U.S. Naval Research Laboratory M. Zachariah, University of Maryland, College Park M.M. Kuklja, University of Maryland, College Park H. Bluhm, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
Filtration systems for absorption and decomposition of chemical warfare agents (CWAs) are the first line of defense against exposure to these toxic compounds. Composite materials (such as ASZM-TEDA) commonly used in filtration systems consist of high-surface-area carbon supports impregnated with various metal oxides, including CuOx. Despite decades of work to develop highly effective and versatile filtration materials, little is known about the mechanisms of CWA degradation by material surfaces and filter deactivation/poisoning, in part due to the challenges involved with spectroscopic characterization of filtration material surfaces under operating conditions. Enabling the rational design of more advanced filtration and decomposition materials for broad-spectrum protection against CWAs and other toxic industrial compounds requires a sophisticated understanding of the chemical mechanisms behind CWA sorption and degradation on the molecular scale.
We will present work detailing the mechanism of adsorption and decomposition of dimethyl methylphosphonate (DMMP), a CWA simulant, on polycrystalline copper oxide surfaces. Ambient-pressure XPS enables examination of these surfaces and adsorbed species upon exposure to DMMP and other common atmospheric gases, such as water vapor and NOx. Multiple decomposition products are observed on CuOx surfaces, and the oxidation state of the metal appears to influence the mechanistic pathway. Complementary density functional theory (DFT) and in situ FTIR studies corroborate our experimental findings and are used to propose likely decomposition pathways. Exposure of the CuOx surfaces to water vapor or NOx prior to introducing DMMP affects the decomposition product distribution, but does not appear to significantly inhibit the initial DMMP adsorption.