AVS 63rd International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS+AS+HC-MoA

Paper SS+AS+HC-MoA10
Adsorption and Decomposition of Dimethyl Methylphosphonate on Metal Oxide Surfaces Under Atmospheric Conditions

Monday, November 7, 2016, 4:40 pm, Room 104E

Session: Metals, Alloys, and Oxides: Reactivity and Catalysis
Presenter: Ashley Head, Lawrence Berkeley National Laboratory (LBNL)
Authors: A.R. Head, Lawrence Berkeley National Laboratory (LBNL)
L. Trotochaud, Lawrence Berkeley National Laboratory (LBNL)
R. Tsyshevsky, University of Maryland College Park
O. Karslioglu, Lawrence Berkeley National Laboratory (LBNL)
M.M. Kuklja, University of Maryland College Park
H. Bluhm, Lawrence Berkeley National Laboratory (LBNL)
Correspondent: Click to Email
Organophosphonates are used as corrosion inhibitors, pesticides, insecticides, and chemical warfare agents. This class of molecules has a range of acute toxicity, so dimethyl methylphosphonate is commonly used as a proxy for more toxic molecules. Metal oxides are used in applications for binding and decomposing organophosphonates despite little understanding of the chemistry and reactivity, especially in the presence of atmospheric molecules. With the ability to collect photoemission spectra at pressures up to about 25 Torr, ambient pressure XPS is well-suited to investigate the adsorption of DMMP in the presence of other molecules that have relevance to applications. Using MoOx and CuOx foils as model systems for chemical filtration materials, we have studied the adsorption and decomposition behavior of DMMP and how this behavior changes in the presence of atmospherically relevant molecules, including water, hydrocarbons, and NOx. The effect of the small molecules on the substrate and the subsequent effects on DMMP binding, coverage, and decomposition will be discussed. APXPS results are interpreted with the aid of density functional theory calculations, which model DMMP adsorption, decomposition products, and reaction energies.