Computational Studies of H۲S Adsorption by Silver-Sulfur-based MOFs

Hydrogen sulfide (H۲S) adsorption using metal-organic frameworks (MOFs) poses challenges due to the formation of strong sulfur-metal bonds, which can degrade structural integrity. However, sulfur-coordinated coordination polymers (SCPs) incorporating divalent metals (Zn²⁺, Cd²⁺, Hg²⁺) and monovalent silver (I) ions exhibit robust stability during repeated adsorption-desorption cycles. In this study, two silver-sulfur-based MOFs SCU-۱ and SCU-۲, were computationally investigated for their H۲S adsorption potential. All computations were performed using the Vienna Ab Initio Simulation Package (VASP). SCU-۱ exhibits a large cationic framework (unit cell volume ~۱۰,۰۰۰ ų) with ۱۵.۱% porosity, while SCU-۲ has a simpler structure and lower porosity (۵.۹%). Electrostatic potential (ESP) maps show electron-rich regions around BF₄⁻ and Cl⁻ in SCU-۱, with slightly lower electron density near methimazole rings in SCU-۲. SCU-۱ exhibits a stronger H۲S adsorption energy (Eads = -۴۵.۰ kJ mol⁻¹) than SCU-۲ (Eads = -۳۹.۰ kJ mol⁻¹), attributed to its electron-rich sites. As results, strategic placement of electron-donating groups in the framework design enhances H۲S affinity. This study develops sulfur-based MOFs for efficient H۲S capture, demonstrating their potential in environmental remediation and gas purification.

کلیدواژه ها:

H۲S uptake ، ESP Maps ، MOFs