Spectroscopic and Computational Investigation of Room-Temperature Decomposition of a Chemical Warfare Agent Simulant on Polycrystalline Cupric Oxide

Abstract

Certain organophosphorous molecules are infamous due to their use as highly toxic nerve agents. The filtration materials currently in common use for protection against chemical warfare agents were designed before organophosphorous compounds were used as chemical weapons. A better understanding of the surface chemistry between simulant molecules and the individual filtration-material components is a critical precursor to the development of more effective materials for filtration, destruction, decontamination, and/or sensing of nerve agents. Here, we report on the surface adsorption and reactions of a sarin simulant molecule, dimethyl methylphosphonate (DMMP), with cupric oxide surfaces. In situ ambient pressure X-ray photoelectron and infrared spectroscopies are coupled with density functional calculations to propose mechanisms for DMMP decomposition on CuO. We find extensive room temperature decomposition of DMMP on CuO, with the majority of decomposition fragments bound to the CuO surface. We observe breaking of PO-CH3, P-OCH3, and P-CH3 bonds at room temperature. On the basis of these results, we identify specific DMMP decomposition mechanisms not seen on other metal oxides. Participation of lattice oxygen in the decomposition mechanism leads to significant changes in chemical and electronic surface environment, which are manifest in the spectroscopic and computational data. This study establishes a computational baseline for the study of highly toxic organophosphorous compounds on metal oxide surfaces.

Adsorption and Decomposition of DMMP on Size‐Selected (WO3)3 Clusters

“…Using DMMP as a model molecule, the reactivity of many metals and metal oxides toward DMMP has been studied, i. e. MoO 3 , Cu, CuO, MgO, ZnO, CeO 2 , TiO 2 , Y 2 O 3 etc.. As illustrated in these studies, DMMP usually undergoes a step‐wise loss of methoxy groups on the metal oxide surface, resulting in methanol being observed as a common hydrolysis reaction product for DMMP on many oxide surfaces . In addition to the hydrolysis reaction, reduction processes are also observed when surface defects, i. e. oxygen vacancies, are present .…”

“…In addition to the hydrolysis reaction, reduction processes are also observed when surface defects, i. e. oxygen vacancies, are present . It has also been noted that both the acidity and reducibility of metal oxides are known to affect the adsorption behavior and the decomposition pathway of DMMP molecules ,. The acidity of metal oxides can affect the binding strength of the DMMP molecule to Lewis and/or Brønsted acid sites on the surface of metal oxides, while the reducibility of metal oxides enables the production of oxygen vacancies, which act as potential active sites to decompose DMMP molecules via a redox mechanism …”

Water Adsorption and Dissociation on Polycrystalline Copper Oxides: Effects of Environmental Contamination and Experimental Protocol

“…The chemical effects of ambient water are of particular interest for the performance of filtration materials for protection against chemical warfare agents and other toxic gases. [1][2][3] Metals, metal salts, and/or metal oxides are components of commonly utilized filtration materials for absorption and degradation of various toxic organic compounds. 4 Changes in the chemical environment of metalcontaining surfaces by exposure to common atmospheric components (e.g.…”

“…For Cu2O, the samples were heated under vacuum (< 1×10-8 Torr) for at least 30 min to remove adventitious carbon contamination and to reduce any CuO, then cooled to room temperature (~20 °C) in the preparation chamber before being transferred to the APXPS analysis chamber. The Cu oxidation state of the samples was confirmed by a combination of Cu 2p3/2 XPS and Cu L-edge NEXAFS, as described in our previous publication 2. (See Supporting Information Fitting of APXPS spectra and identification of surface species.Representative XPS data for isotherm (20 °C) experiments with CuO and Cu2O are shown in…”

Simple and highly active strontium-based catalyst for detoxification of an organophosphorus chemical warfare agent simulant

“…Sarin itself is categorized as an organophosphorus (OP) chemical warfare agent, a class of compounds that attacks the nervous system through the inhibition of acetylcholinesterase, a process that can be irreversible and lead to death depending on the degree of intoxication and the time taken to administer an antidote (Delfino et al 2009;Mercey et al 2012;Chen et al 2018;Costanzi et al 2018). In this context, several research groups worldwide have directed efforts toward the investigation of homogeneous and heterogeneous catalytic systems for the destruction of organophosphorus biocides and related compounds (Pavez et al 2016;Trotochaud et al 2017;Balow et al 2017Balow et al , 2018Gerola et al 2017;Fonsaca et al 2017;Amaya Vargas et al 2018;Wanderlind et al 2014Wanderlind et al , 2018Wanderlind et al , 2019Ryu et al 2019;Santos et al 2016), looking for safe and low-cost systems able to detoxify these compounds through highly efficient processes.…”