Hydrogen Storage in a Ti-Functionalized Metal Carbyne Framework: Insights from a First-Principles Study

Abstract

Hydrogen (H2) has the ability to be a future green-energy source for the automotive industry due to its versatility, clean nature, and efficiency as an energy carrier. The biggest obstacle to achieving hydrogen as a potential energy source is the nonavailability of effective hydrogen storage materials. In this proposed work, the hydrogen storage capacity and reversibility of a Ti-functionalized metal carbyne framework (MCF) having carbyne as an organic linker and Mg4O as an inorganic moiety are explored. All structural relaxation and simulation calculations are performed by employing the dispersion-corrected density functional theory computation. In this Ti-functionalized MCF, each Ti can adsorb up to five H2 molecules via the Kubas mechanism, with adsorption energy lying between 0.33 and 0.44 eV, which falls within the range outlined by the U.S. Department of Energy (DOE). For a detailed study of the thermal stability of framework, hydrogen reversibility, and mechanism of hydrogen sorption, Born–Oppenheimer molecular dynamics (BOMD) simulations are carried out at various temperatures. From the findings of BOMD simulations, the Ti-functionalized MCF can reversibly adsorb the H2 molecules with a high gravimetric density of about 9.4 wt %. This proposed Ti-functionalized MCF stands out as a potential hydrogen storage medium meeting the standards established by the DOE.