Humidity-dependent CO2 capture in ultraporous MOF-177: Insights from hybrid GCMC/MD simulations

With rising atmospheric CO₂ levels, the need for efficient adsorbent materials has become increasingly important. Among all the porous materials, metal-organic frameworks (MOFs) are gaining considerable attention because of their large surface area, tunable pore sizes, and diverse chemical and physical properties. In this study, we used hybrid Grand Canonical Monte Carlo and Molecular Dynamics (GCMC/MD) simulations in LAMMPS to explore CO₂ adsorption and diffusion in MOF-177 under varying pressures, temperatures, and humidity levels. CO₂ uptake increased from 17.19 to 26.92 mmol/g (56.6 %) as pressure rose from 10 to 100 bar. Adsorption decreased by 30.1 % when temperature increased from 298 K to 318 K due to enhanced molecular motion. The diffusion coefficient dropped exponentially with pressure but increased with temperature. At 15 wt% humidity, CO₂ adsorption decreased by 12.5 % due to competition with water, which also reduced diffusion. These findings help to understand CO₂ sequestration under realistic conditions.