The Electronic State of Hydrogen in the α Phase of the Hydrogen-Storage Material PdH(D)x : Does a Chemical Bond Between Palladium and Hydrogen Exist?

Shun Dekura; Hirokazu Kobayashi; Ryuichi Ikeda; Mitsuhiko Maesato; Haruka Yoshino; Masaaki Ohba; Takayoshi Ishimoto; Shogo Kawaguchi; Yoshiki Kubota; Satoru Yoshioka; Syo Matsumura; Takeharu Sugiyama; Hiroshi Kitagawa

doi:10.1002/anie.201805753

The Electronic State of Hydrogen in the α Phase of the Hydrogen-Storage Material PdH(D)_x : Does a Chemical Bond Between Palladium and Hydrogen Exist?

Angew Chem Int Ed Engl. 2018 Jul 26;57(31):9823-9827. doi: 10.1002/anie.201805753. Epub 2018 Jul 6.

Authors

Shun Dekura¹, Hirokazu Kobayashi^{1

2}, Ryuichi Ikeda¹, Mitsuhiko Maesato¹, Haruka Yoshino³, Masaaki Ohba³, Takayoshi Ishimoto^{4

5}, Shogo Kawaguchi⁶, Yoshiki Kubota⁷, Satoru Yoshioka⁸, Syo Matsumura^{8

9}, Takeharu Sugiyama¹⁰, Hiroshi Kitagawa¹

Affiliations

¹ Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, 606-8502, Japan.
² Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Honcho 4-1-8, Kawaguchi, Saitama, 332-0012, Japan.
³ Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
⁴ Institute of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8527, Japan.
⁵ Current address: Quantum Chemistry Division, Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027, Japan.
⁶ Japan Synchrotron Radiation Research Institute (JASRI) SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198, Japan.
⁷ Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, 599-8531, Japan.
⁸ Department of Applied Quantum Physics and Nuclear Engineering, Graduate School of Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan.
⁹ The Ultramicroscopy Research Center, Kyushu University, Motooka 744, Nishi-ku, Fukuoka, 819-0395, Japan.
¹⁰ Research Center for Synchrotron Light Applications, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan.

PMID: 29896769
DOI: 10.1002/anie.201805753

Abstract

The palladium-hydrogen system is one of the most famous hydrogen-storage systems. Although there has been much research on β-phase PdH(D)_x , we comprehensively investigated the nature of the interaction between Pd and H(D) in α-phase PdH(D)_x (x<0.03 at 303 K), and revealed the existence of Pd-H(D) chemical bond for the first time, by various in situ experimental techniques and first-principles theoretical calculations. The lattice expansion, magnetic susceptibility, and electrical resistivity all provide evidence. In situ solid-state ¹ H and ² H NMR spectroscopy and first-principles theoretical calculations revealed that a Pd-H(D) chemical bond exists in the α phase, but the bonding character of the Pd-H(D) bond in the α phase is quite different from that in the β phase; the nature of the Pd-H(D) bond in the α phase is a localized covalent bond whereas that in the β phase is a metallic bond.

Keywords: chemical bonding; hydrogen; hydrogen storage; palladium; solid-state chemistry.