Ferrocene-functionalized covalent organic framework exceeding the ultimate hydrogen storage targets: a first-principles multiscale computational study

Abstract: The development of efficient hydrogen storage materials is crucial for advancing the hydrogen economy and meeting the U.S. Department of Energy's targets of 6.5 wt\% and 50 g \ce{H2} L$^{-1}$ for automotive applications. We present a computational study of ferrocene-functionalized covalent organic frameworks (COFs) for hydrogen storage. Following the \textbf{M}ulti-binding \textbf{S}ites \textbf{U}nited in \textbf{C}ovalent-\textbf{O}rganic \textbf{F}ramework (MSUCOF) approach, we introduce MSUCOF-4-FeCp, designed by incorporating ferrocene (\ce{FeCp2}) moieties into IRCOF-102. Notably, it achieves exceptional performance with gravimetric and volumetric uptakes of 18.0 wt\% and 72.6 g \ce{H2} L$^{-1}$ at 298 K and 700 bar. The material exhibits optimal binding energies (15--20 kJ$\cdot$mol$^{-1}$) ensuring both high storage capacity and deliverable hydrogen under practical conditions. This work establishes ferrocene functionalization as a cost-effective alternative to precious metal incorporation in COFs.