Kim, Hayoung Kang, ShinYoung Lee, Ji Yeong Heo, Tae Wook Wood, Brandon C. Shim, Jae-Hyeok Cho, Young Whan Kim, Do Hyang Suh, Jin-Yoo Lee, Young -Su 2024-01-19T10:04:37Z 2024-01-19T10:04:37Z 2023-01-26 2023-02 0169-4332 https://pubs.kist.re.kr/handle/201004/114056 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 acti-vation 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. English Elsevier BV 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 Article 10.1016/j.apsusc.2022.155443 1 Applied Surface Science, v.610 Applied Surface Science 610 Y scie scopus 000906881100006 2-s2.0-85143827681 Chemistry, Physical Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Chemistry Materials Science Physics Article SUBSTITUTION SEGREGATION KINETICS PLASTIC-DEFORMATION XPS ANALYSIS TIFE ACTIVATION STORAGE MICROSTRUCTURE ZR Hydrogen storage TiFe alloy Activation Surface oxide Density functional theory calculation Atom probe tomography