Lithium-Ion Doping for Enhanced Hydrogen Sulfide Adsorption on Metal–Organic Frameworks: Grand Canonical Monte Carlo and Density Functional Theory Simulations

The use of metal–organic frameworks (MOFs) has emerged as a promising solution for sequestering toxic hydrogen sulfide (H2S). To find the best conditions for improving the H2S adsorption performance, we conducted grand canonical Monte Carlo simulations based on high-throughput screening of 20 selected materials. Furthermore, we used lithium-ion doping to modify materials that showed potential for further improvement. Density functional theory calculations helped us identify lithium-ion doping sites. Our findings revealed that lithium-ion doping could effectively increase the H2S adsorption capacity of the original MOF structure. Among all of the doping methods, double-sided opposite doping showed the most notable improvement in the H2S adsorption capacity of MOFs. Lithium-ion doping altered the H2S-molecule adsorption sites in the MOFs, shifting from dispersion to concentration. This change in adsorption sites was caused by the modification of van der Waals and electrostatic forces between molecules, where van der Waals forces played a dominant role. The research findings indicate that not all lithium-ion doping methods could enhance the H2S adsorption capacity of MOFs. When double-sided misaligned doping sites are used, certain materials (QUQGAL and HIKQOK) may exhibit a decreased adsorption capacity. This study provides a theoretical foundation for applying lithium-ion doping to improve H2S adsorption on MOFs.