Abstract
Metal hydrides are potential candidates for applications in hydrogen-related technologies, such as energy storage, hydrogen compression, and hydrogen sensing, to name just a few. However, understanding the electronic structure and chemical environment of hydrogen within them remains a key challenge. This work presents a new analytical pathway to explore these aspects in technologically relevant systems using hard x-ray photoelectron spectroscopy (HAXPES) on thin films of two prototypical metal dihydrides: and . By taking advantage of the tunability of synchrotron radiation, a nondestructive depth profile of the chemical states is obtained using core-level spectra. Combining experimental valence-band (VB) spectra collected at varying photon energies with theoretical insights from density functional theory (DFT) calculations, a description of the bonding nature and the role of versus contributions to states near the Fermi energy are provided. Moreover, a reliable determination of the enthalpy of formation is proposed by using experimental values of the energy position of metal -band features close to the Fermi energy in the HAXPES VB spectra.
- Received 30 May 2023
- Revised 28 September 2023
- Accepted 2 November 2023
DOI:https://doi.org/10.1103/PRXEnergy.3.013003
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Metal hydrides hold significant promise in various hydrogen-related technologies, such as energy storage, hydrogen compression, and hydrogen sensing. Yet, unlocking their full capabilities requires a profound understanding of their electronic structure and chemical characteristics. This study introduces an innovative approach to comprehensively explore these critical aspects within technologically relevant systems, employing hard x-ray photoelectron spectroscopy (HAXPES) and density functional theory. By examining thin films of two prototypical metal dihydrides, yttrium and titanium dihydride, this research offers valuable insights into the nature of chemical bonds present and the occupied states close to the Fermi energy that largely control their behavior. By combining experiment and theory, a direct connection is found between specific electronic states within the materials and their enthalpy of formation. This work bolsters our understanding of metal hydrides, which is crucial for driving advancements in hydrogen-related technologies.