Decomposition of Diisopropyl Methylphosphonate and Fluorine-Substituted Isomers on Mixed Metal Oxide Surfaces: Mechanisms from Ab Initio Molecular Dynamics

Mixed metal oxide surfaces have attracted significant interest in their ability to efficiently neutralize organophosphorus-based chemical warfare agents (CWAs). However, these processes occur under complex reactive conditions at high temperatures, and the detailed mechanisms of the neutralization process are not well understood. To shed mechanistic insight into the neutralization process, we have carried out extensive quantum calculations to investigate the high-temperature degradation of diisopropyl methylphosphonate (DIMP), a simulant for chemical warfare agents, as well as its fluorine-substituted isomer. Our Born-Oppenheimer molecular dynamics (BOMD) simulations reveal that the CuAl2O4 (110) surface rapidly adsorbs DIMP/fluorine-substituted DIMP, resulting in subsequent decomposition via C–O bond cleavage and propene elimination. Our quantum calculations provide detailed insight into the atomistic decomposition mechanisms of DIMP/fluorine-substituted DIMP to guide future efforts on neutralizing these hazardous compounds.