Achieving Rapid, Nonbuffered Nerve Agent Hydrolysis with Alkali-Loaded MOFs: Insights from KWW Kinetic Modeling

Abstract

Nerve agents, a class of extremely toxic chemical warfare agents, pose a severe threat, making their rapid degradation an urgent necessity. Zirconium-based metal-organic frameworks are promising catalysts for hydrolyzing organophosphorus nerve agents, but their practical application is severely hampered by the reliance on external alkaline buffers to regenerate active sites. Furthermore, conventional kinetic models are inadequate for fully describing the time-dependent catalytic behavior. Herein, we report a general strategy to overcome these limitations by constructing a built-in alkaline microenvironment within nanoflower-like zirconium-based metal-organic frameworks (denoted as MOFF/Mg-n) through loading magnesium methoxide. In this dual-component system, the Zr6 nodes function as catalytic centers while the loaded Mg(OMe)2 serves as a consumable alkaline reservoir. Under the tested conditions (Zr6:DMNP = 1:2), the optimized catalyst MOFF/Mg-2 exhibits a significantly shortened hydrolysis half-life of only 2.8 min toward nerve-agent simulant dimethyl 4-nitrophenyl phosphate (DMNP) under nonbuffered conditions, while MOFF/Mg-4 can hydrolyze DMNP almost completely within 20 min. To gain deeper insight into the kinetic behavior of this complex system, we successfully applied the Kohlrausch-Williams-Watts (KWW) stretched-exponential model, which provided an excellent fit of the experimental data and yielded two key parameters of the characteristic rate constant and the stretching exponent, for quantitative performance evaluation. This work demonstrates that constructing a built-in alkaline microenvironment is a feasible and powerful strategy for achieving efficient, nonbuffered nerve agent degradation, paving a new route for practical decontamination in real-world scenarios. Moreover, the successful application of the KWW model provides a robust empirical kinetic framework for designing and evaluating high-performance decontamination catalysts for complex surface reactions. The system operates as a reusable MOF scaffold with a replenishable alkaline reservoir, enabling sustained performance through simple re-impregnation of Mg (OMe)2.