Metal-organic frameworks (MOFs) are a promising class of catalysts for chemical warfare agent degradation. Experiments have shown that MOFs with Zr<sub>6</sub> nodes can adsorb and catalytically degrade nerve agents into nontoxic products within a matter of minutes under alkaline-solution conditions via hydrolysis of the phosphate ester bond. However, recent studies have shown that the gas-phase hydrolysis of nerve agents on Zr<sub>6</sub> nodes is potentially stoichiometric rather than catalytic. This can be attributed to strong product inhibition resulting from the bidentate binding of the hydrolysis product to the Zr atoms in the MOF node. A potential method to avoid this problem is to deposit transition metals as single-atom catalysts on the nodes so that products would bind in a more favorable monodentate fashion. Atomic layer deposition or solvothermal deposition can be used to synthesize such systems, and these well-defined catalytic active sites enable detailed computational mechanistic studies. Thus, we used density functional theory to perform a comprehensive screening of single-atom metals in the +2, +3, and +4 oxidation states deposited on NU-1000 for the gas-phase hydrolysis of sarin. We studied periodic trends based on oxidation state and electronic structure and explored molecular descriptors for their effect on catalytic activity. We calculated the complete reaction pathways for selected M-NU-1000 systems and compared their relative kinetics, identifying promising candidates for future experimental synthesis and testing. The effect of surrounding water molecules, to simulate the moisture that would be present in a relevant humid gas-mask environment, was also investigated. Understanding these trends can help establish design principles to optimize MOF systems for catalytic nerve agent destruction.

Computational screening of NU-1000-supported transition metal catalysts for the hydrolysis of sarin

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.