Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts

Masaaki Kitano, Yasunori Inoue, Hiroki Ishikawa, Kyosuke Yamagata, Takuya Nakao, Tomofumi Tada, Satoru Matsuishi, Toshiharu Yokoyama, Michikazu Hara, Hideo Hosono

Research output: Contribution to journalArticle

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Abstract

The efficient reduction of atmospheric nitrogen to ammonia under low pressure and temperature conditions has been a challenge in meeting the rapidly increasing demand for fertilizers and hydrogen storage. Here, we report that Ca2N:e-, a two-dimensional electride, combined with ruthenium nanoparticles (Ru/Ca2N:e-) exhibits efficient and stable catalytic activity down to 200 °C. This catalytic performance is due to [Ca2N]+·e1-x-Hx- formed by a reversible reaction of an anionic electron with hydrogen (Ca2N:e- + xH ↔ [Ca2N]+·e1-x-Hx-) during ammonia synthesis. The simplest hydride, CaH2, with Ru also exhibits catalytic performance comparable to Ru/Ca2N:e-. The resultant electrons in these hydrides have a low work function of 2.3 eV, which facilitates the cleavage of N2 molecules. The smooth reversible exchangeability between anionic electrons and H- ions in hydrides at low temperatures suppresses hydrogen poisoning of the Ru surfaces. The present work demonstrates the high potential of metal hydrides as efficient promoters for low-temperature ammonia synthesis.

Original languageEnglish
Pages (from-to)4036-4043
Number of pages8
JournalChemical Science
Volume7
Issue number7
DOIs
Publication statusPublished - Jan 1 2016

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Ruthenium
Ammonia
Hydrides
Ions
Catalysts
Electrons
Hydrogen
Fertilizers
Hydrogen storage
Temperature
Catalyst activity
Nitrogen
Metals
Nanoparticles
Molecules

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

Kitano, M., Inoue, Y., Ishikawa, H., Yamagata, K., Nakao, T., Tada, T., ... Hosono, H. (2016). Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts. Chemical Science, 7(7), 4036-4043. https://doi.org/10.1039/c6sc00767h

Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts. / Kitano, Masaaki; Inoue, Yasunori; Ishikawa, Hiroki; Yamagata, Kyosuke; Nakao, Takuya; Tada, Tomofumi; Matsuishi, Satoru; Yokoyama, Toshiharu; Hara, Michikazu; Hosono, Hideo.

In: Chemical Science, Vol. 7, No. 7, 01.01.2016, p. 4036-4043.

Research output: Contribution to journalArticle

Kitano, M, Inoue, Y, Ishikawa, H, Yamagata, K, Nakao, T, Tada, T, Matsuishi, S, Yokoyama, T, Hara, M & Hosono, H 2016, 'Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts', Chemical Science, vol. 7, no. 7, pp. 4036-4043. https://doi.org/10.1039/c6sc00767h
Kitano, Masaaki ; Inoue, Yasunori ; Ishikawa, Hiroki ; Yamagata, Kyosuke ; Nakao, Takuya ; Tada, Tomofumi ; Matsuishi, Satoru ; Yokoyama, Toshiharu ; Hara, Michikazu ; Hosono, Hideo. / Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts. In: Chemical Science. 2016 ; Vol. 7, No. 7. pp. 4036-4043.
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