Theory, synthesis and characterization of nano-scale architectures for solid-state hydrogen storage

Traditional materials discovery and development techniques have not yet yielded the necessary breakthroughs needed for practical utilization of hydrogen storage. An integrated theoretical-experimental approach to the development of novel materials capable of hydrogen storage under the narrow thermodynamic regime suitable for automotive applications is undertaken.;The viability of engineering two-part nano-architectures (heterostructures) to enhance the binding energy between molecular hydrogen and solid-state nanostructures, or to evince dissociation and uptake of hydrogen into the architecture, was explored. First, exceptional hydrogen uptake (7.5 wt.%) was validated in a metal organic framework compound, MOF-177, at low temperature (77 K), and a thermodynamic model for physisorption was established as a benchmark for all such structures. A chemisorptive pathway for enhanced hydrogen uptake (2.2 wt.%) at room temperature in heterostructures of metal-organic-frameworks (MOFs), via a mechanism now referred to as hydrogen spillover, was experimentally validated and further studied through computations. Ab initio computations at the level of Hartree-Fock (HF) and density functional theories (DFT) made it possible to calculate the thermochemical properties of hydrogen uptake in Pt-doped MOF heterostructures, which verified the thermodynamic plausibility of hydrogen spillover. Furthermore, the hydrogen spillover mechanism was successfully elicited from heterostructures consisting of metal-doped carbon materials, which yielded the highest uptake of hydrogen ever measured at room temperature (8.0 wt.%) for carbon-based material.;The theoretical foundation was formed for a new way of considering how binding interactions between small molecules, such as dihydrogen, and an engineered surface may be influenced by coupling molecular vibrations with low-frequency surface plasmons in clusters of a metal compound. Finally, new MOF-based heterostructures in which a metal dopant is effectively caged within the pore structure were successfully synthesized using a new method of generating metal clusters. These unique structures were specifically engineered to take advantage of hydrogen spillover effects and to overcome the kinetic barriers associated with this mechanism.;The results of this work have provided long-range benefits to the hydrogen storage field. More generally, this research has laid down the groundwork for important spin-off applications in catalysis, nanomaterials, spectroscopy, and plasmonics.