Issue 7, 2016

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

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−xHx formed by a reversible reaction of an anionic electron with hydrogen (Ca2N:e + xH ↔ [Ca2N]+·e1−xHx) 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.

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

Associated articles

Supplementary files

Article information

Article type
Edge Article
Submitted
19 feb 2016
Accepted
21 apr 2016
First published
21 apr 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2016,7, 4036-4043

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

M. Kitano, Y. Inoue, H. Ishikawa, K. Yamagata, T. Nakao, T. Tada, S. Matsuishi, T. Yokoyama, M. Hara and H. Hosono, Chem. Sci., 2016, 7, 4036 DOI: 10.1039/C6SC00767H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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