Controlling hydrogen release from remaining-intact Clathrate hydrates by electromagnetic fields: molecular engineering via microsecond non-equilibrium molecular dynamics

Abstract

In view of the recently-predicted hydrogen release from type-II (sII) clathrate hydrates in the general 140–180 K temperature range [J. Phys. Chem. C, 125, 8430–8439 (2021)], we have investigated in the present study, by means of microsecond-long non-equilibrium molecular-dynamics simulation, the effect of externally-applied electric fields (both static and alternating) on manipulating and accelerating this H₂-escape process. In particular, we have found that judiciously-selected electromagnetic fields, in the microwave frequency range, serve to enhance dramatically this H₂-release rate – crucially, without any breakup of the hydrate lattice itself. Of those studied, we have found that 10 GHz serves as the optimal frequency to maximise hydrogen release, owing to promotion of H₂–H₂ molecular collisions inside doubly-occupied 5¹²6⁴ cages in the sII structure and optimal field-period overlap with intra-cage tetrahedral-site hopping and opportunities for inter-cage passage via hexagonal cage faces. This study opens up the vista of “field engineering” for exquisite kinetic control of large, Grid-(terawatt hour)-scale hydrogen-storage systems.