Hydrogen interaction with metal/metal oxides is an important phenomenon that affects all areas of life. Metal oxides provide a naturally formed protective layer against dissolution of the underlying metal. It has been reported that hydrogen is still able to percolate through this protective layer incorporating into the metal to form a corrosive brittle metal hydride. Hydrides are a current interest for hydrogen storage applications but for industry applications such as aerospace, transportation, and commercial this phase transformation is often undesirable due to inferior mechanical properties which can incur catastrophic failures. There have been many studies looking to understand the interaction of hydrogen at the surface but an in depth look at the surface to bulk transition of hydrogen through a metal oxide for all representative phases of an oxide is minimally represented in the literature. For the focus of our study, we employed a multi-scale approach theoretical study to explore the different phases of titania (TiO2) which includes rutile, anatase, and an amorphous phase. A thermodynamic analysis of the stability for hydrogen was considered using density functional theory (DFT) starting at the low energy surface facets of the bulk. For the amorphous phase, the binding energy was analyzed as a function of the hydrogen content and oxygen coordination environment. Additionally, NMR simulations validified the generated amorphous phase which agreed well with experimental data. The material properties computed using DFT were used in combination with experimental results to parameterize a mesoscale model. Several environmental conditions were analyzed consisting of grain size, temperature, and grain boundary properties. Further work investigated crystalline titanium (Ti) in the bulk and at several grain boundaries to elucidate possible initiation stages of hydride formation.

Multiscale understanding of local structure-dependent hydrogen incorporation in TiO<sub>2</sub>

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Multiscale understanding of local structure-dependent hydrogen incorporation in TiO2

Multiscale understanding of local structure-dependent hydrogen incorporation in TiO₂