Emulsion architecture Controls the efficiency of hydrogen storage into ternary clathrate hydrates of H2 and mixed Hydrophobic/Hydrophilic co-formers

Abstract

Clathrate hydrates are promising materials for solid-state hydrogen storage, yet their practical application is hindered by extreme pressure-temperature requirements and slow formation kinetics. While traditional co-formers can moderate these conditions, they typically do so at the cost of significantly reduced hydrogen capacity. Here we report the discovery of a synergistic stabilization mechanism in ternary hydrogen hydrates achieved through the simultaneous use of mixed hydrophobic (cyclopentane) and hydrophilic (1,3-dioxolane, tetrahydrofuran, or tetrahydropyran) co-formers within tailored surfactant emulsions.We demonstrate that the architecture of the emulsion interface—controlled by the surfactant geometry—is the primary determinant of hydrate performance as H2 storage material. Using bicontinuous/reverse emulsions, we observe a remarkable 3 K increase in dissociation temperatures for the cyclopentane/1,3-dioxolane system compared to its single-promoter counterparts, an increase of hydrogen storage capacities which reached approximately 0.6 wt%, and formation times shortened to tens of minutes. This synergy is driven by the distinct chemical nature of the co-formers, and the architecture of the emulsions.In-situ Raman spectroscopy and density functional theory (DFT) calculations confirm the differential entrapment of both hydrophilic and hydrophobic co-formers, revealing that 1,3-dioxolane facilitates a unique lattice flexibility that optimizes cage filling, hydrate stabilization, and formation kinetics. These results establish a new paradigm for designing clathrate materials through cooperative guest-host interactions, providing a scalable pathway for efficient, large-scale hydrogen energy storage.