A new perspective on the initial hydrogenation of TiFe0.9M0.1 (M = V, Cr, Fe, Co, Ni) alloys gained from surface oxide analyses and nucleation energetics

Hayoung Kim, Shin Young Kang, Ji Yeong Lee, Tae Wook Heo, Brandon C. Wood, Jae Hyeok Shim, Young Whan Cho, Do Hyang Kim, Jin Yoo Suh, Young Su Lee

Research output: Contribution to journalArticlepeer-review


Despite the promise of TiFe-based alloys as low-cost solid-state hydrogen storage materials with mild operating conditions and reasonable hydrogen capacity, their initial hydrogenation process is difficult, hindering broad utilization. The effect of alloying element on the initial hydrogenation kinetics of TiFe alloys, TiFe0.9M0.1 (M = V, Cr, Fe, Co and Ni), was evaluated by analyzing changes to the passivating surface oxide layer that inhibits hydrogen permeation, as well as the ease of initial-stage hydrogen absorption into the underlying matrix. X-ray photoelectron spectroscopy and atom probe tomography revealed key variations in surface oxide compositions and thinning of the passivating oxide layer compared to pure TiFe, which suggests suppressed oxide growth by alloying-induced elemental redistribution. At the same time, density functional theory calculations predicted exothermic formation of hydride nuclei when alloying with V or Cr, as well as a reduced nucleation barrier when alloying with Co or Ni. Overall, these results are consistent with the observed experimental trend of the activation kinetics. We propose that improvements in activation kinetics of TiFe with alloying arises from the combined effect of reduced passivating oxide thickness and easier hydride nucleation, offering a starting point for alloy design strategies towards further improvement.

Original languageEnglish
Article number155443
JournalApplied Surface Science
Publication statusPublished - 2023 Feb 1

Bibliographical note

Funding Information:
This research was supported by the Korea Institute of Science and Technology [grant numbers 2E31851, 2E31858] and by the National Research Foundation of Korea [grant number NRF-2020M1A2A2080881]. Part of this study was performed under the auspices of the DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344, with support from the Hydrogen Materials Advanced Research Consortium (HyMARC), established as part of the Energy Materials Network by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, under Contract No. DE-AC52-07NA27344. Computational resources were sponsored by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program and the DOE's Office of EERE, located at the Argonne National Laboratory and National Renewable Energy Laboratory.

Publisher Copyright:
© 2022 The Author(s)

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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