Fluoride Product Inhibition: New Insight into the Degradation of Nerve Agents by Zr-MOFs.

Abstract

Zirconium-based metal-organic frameworks (Zr-MOFs) have shown remarkable efficacy in catalytically degrading neurotoxic agents in recent years. However, the catalytic activity of Zr-MOFs can be inhibited due to the binding of phosphate degradation products to the Zr nodes. Here, we reported the inhibition effect of a nonphosphate substance, fluoride, which can deactivate Zr-MOF nodes for the degradation of GD and VX and simulate DEPPT. The experimental and theoretical calculation results reveal that the fluoride product during GD degradation shows much more significant suppression than phosphate. The phosphate products can depart from the Zr nodes completely by adding H₂O molecules on the Zr nodes to reduce the energy barrier. However, the fluoride can replace the bridged μ₃-OH groups and terminal -OH groups on Zr-oxo clusters irreversibly, changing the electric density of Zr nodes and eliminating the terminal -OH. Without the terminal -OH, the five-coordinate phosphorus intermediate cannot be formed, resulting in the inactivation of Zr-O-Zr sites. This study provides new insights into Zr-MOF catalyst deactivation mechanisms and may help to develop a new strategy to design MOFs with high anti-inhibition efficiency for the degradation of nerve agents.