Exploring the Heat of Water Intrusion into a Metal-Organic Framework by Experiment and Simulation

Area of Science:

• Materials Science
• Physical Chemistry
• Nanotechnology

Background:

• Wetting processes are crucial in nature and technology.
• Heat generation during wetting, especially in nanoconfined systems, is not well understood.
• Understanding these phenomena is key to advancing various scientific and engineering fields.

Purpose of the Study:

• To quantify the pressure-driven heat of intrusion of water into ZIF-8 powder.
• To investigate the influence of temperature and environmental conditions on this process.
• To elucidate the behavior of confined water within ZIF-8 using combined experimental and simulation approaches.

Main Methods:

• Scanning transitiometry was employed to experimentally measure the heat of intrusion.
• Molecular dynamics simulations were performed to complement experimental findings.
• Experiments were conducted across a temperature range of 278.15–343.15 K, varying conditions like gas presence and pH.

Main Results:

• The experimental heat of intrusion of water into ZIF-8 at 298 K was -10.8 ± 0.8 J·g^-1.
• A significant temperature-dependent increase in heat of intrusion was observed, rising by 19.2 J·g^-1 from 298 K to 343 K.
• Simulation results closely matched experimental data, predicting a 16.1 J·g^-1 rise over the same temperature range.

Conclusions:

• A temperature-dependent thermodynamic cycle model was developed to explain the observed phenomena.
• The study clarifies the role of confined water in the heat of intrusion in ZIF-8.
• Findings provide critical data for understanding and manipulating interfacial phenomena in nanoporous materials.