Hydrogen is emerging as an important renewable fuel source in the global effort to decarbonize the energy network. However, a lack of suitable storage materials has so far hindered the widespread adaptation of hydrogen as a fuel source. New materials with enhanced storage capacities at operationally relevant pressure and temperature conditions are required, both for stationary and mobile end use applications. Among the candidate storage materials known today, metal–organic framework and metal hydrides stand out as particularly promising for hydrogen storage applications. Here we present powder neutron diffraction, powder X-ray diffraction, gas adsorption isothermal, and inelastic neutron scattering measurements paired with density functional theory calculations of three candidate storage materials. Specifically, we employ in situ gas dosing powder neutron and X-ray diffraction measurements in combination with variable temperature, high pressure isothermal measurements of two MOFs: ZIF-7 and CdIF-13. The diffraction measurements yield detailed microscopic insight into the gas-induced flexibility in these species, which can be synthetically tuned and thus leveraged to enhance their storage capabilities. Secondly, we present inelastic neutron scattering measurements in tandem with density functional theory calculations conducted on the RNiInH_x metal hydrides (R = La, Ce; x = 1.4, 1.6), which contain close H-H contacts in violation of the Switendick-Westlake criterion. Rationally violating this criterion may enable enhanced volumetric capacities in metal hydrides. The results from the neutron scattering measurements on these candidate storage systems point towards refined design criteria which will help lead to the realization of suitable hydrogen storage materials.

Craig Brown

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