Stability by Design: Atomistic Insights into Hydrolysis-Driven MOF Degradation

TL;DR

This study uses molecular dynamics to analyze the stability of Zn-based MOFs in humid conditions, revealing how linker chemistry influences hydrolysis and stability, which is vital for improving CO2 capture materials.

Contribution

It provides atomistic insights into MOF hydrolysis mechanisms and correlates stability with linker properties, aiding the design of more durable MOFs for carbon capture.

Findings

ZIFs show higher water stability than IRMOFs.

Water stability depends on linker size and chemistry.

Hydrolysis energy barriers correlate with MOF descriptors.

Abstract

Metal-organic frameworks (MOFs) are porous materials formed by interconnected metal atoms via organic linkers, resulting in high surface area and tuneable porosity, making them exceptional candidates for CO2 capture. However, their stability and efficacy in humid conditions are not fully understood, often limiting their commercial applications. Here, we estimate the stability of seven common Zn-based MOFs using reactive molecular dynamics (MD) along with metadynamics sampling to determine hydrolysis energetics at conditions representative of low water concentration limit. The reactions' free energy surfaces (FESs) showed that water stability strongly depends on its linker size and chemistry. Our findings indicate zeolitic imidazolate frameworks (ZIFs), a subclass of MOFs, exhibit higher water stability than iso-reticular metal-organic frameworks (IRMOFs). We further attempt to correlate hydrolysis energy barrier with the physicochemical descriptors of these MOFs. This study provides insights into the critical factors and fundamental implications for developing stable porous materials for carbon capture technologies.