Computational Screening of Covalent Organic Frameworks for Hydrogen Storage

Abstract

Covalent Organic Frameworks (COFs) have been considered as promising materials for gasstorage applications due to their highly porous structures and tunable characteristics. In this work,high-throughput molecular simulations were performed to screen the recent Computation-ReadyExperimental COF Database (CoRE-COF) for H2 storage as a first time in the literature. Predictions forH2 uptakes were first compared with the experimental data of several COFs. Motivated from the goodagreement between simulations and experiments, we performed Grand Canonical Monte Carlo (GCMC)simulations to compute volumetric H2 uptakes of 296 COFs at various temperatures and pressures andidentified the best candidates which exhibit superior performance for H2 storage. COFs outperformedseveral well-known MOFs such as HKUST-1, NU-125, NU-1000 series, NOTT-112 and UiO-67 at 100bar/77 K adsorption and 5 bar/160 K desorption conditions. We also examined the effect of FeynmanHibbs correction on simulated H2 isotherms and H2 working capacities of COFs to consider quantumeffects at low temperatures. Results showed that the Feynman-Hibbs corrections do not affect theranking of materials based on H2 working capacities, but slightly affect the predictions of H2 adsorptionisotherms. We finally examined the structure-performance relations and showed that density andporosity are highly correlated with the volumetric H2 working capacities of COFs. Results of this studywill be highly useful in guiding future research and focusing experimental efforts on the best COFadsorbents identified in this study.