Nanoparticulate Pt-Catalyzed Hydrogenation of Yb Films: Towards Hydrides with Higher Hydrogen Compositions

Toshihiro Yoshizumi,  Keigo Koshiba, Satoru Kitsunai,  Teru Yoshizawa,   Osamu Nakamura,  Masamichi Sakai (corr-auth)

It is more difficult to synthesize β-phase ytterbium trihydride (β-YbH3−δ) under moderate conditions than other rare-earth metal trihydrides because it requires a valence change from a fully occupied
 shell (
) in Yb2+ to an unclosed shell (
) in Yb3+. We synthesized β-YbH3−δ at ambient pressure through hydrogenation of a Yb film capped with platinum (Pt) nanoparticle (NP) catalysts. In addition, Pt NP capping enabled us to synthesize α-phase Yb dihydride (α-YbH2±δ) at room temperature. The difficulty of trihydrogenating Yb to β-YbH3−δ is explained by kinetic analyses based on temperature and time dependences of molar fractions of α-YbH2±δ and β-YbH3−δ. Pt NP capping can be used to synthesize other hydrogen-rich rare-earth metal hydrides under ambient pressure and lower temperatures.  

Chemical Physics

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