Maarten_pic_hydridesA scientific curiosity with promising potential
by Dr. Maarten Verbraeken

The hydrides of the heavy alkaline earth metals (Ca, Sr, Ba) show high hydrogen mobility in the solid state. The mobile species in these materials is the negatively charged hydride ion (H) and since the transport properties are predominantly of ionic nature, they would be suitable as electrolyte materials. The hydride ion itself is a strong reducing agent and therefore chemically of great interest. An electrochemical device involving hydride ions could offer new energy efficient ways of synthesising base chemicals, like ammonia or methane from the elements or fully oxidised compounds. Here we try to understand the mechanisms for hydride ion conduction by creating defect chemistry in the parent materials. Various doping strategies are being researched to enhance hydride mobility. New phases are also being synthesised and their structural and electrical properties characterised. Mixed conducting phases would be of particular interest as electrode materials.

Nitrogen can also be incorporated into these materials to form a range of nitrided materials, such as nitride hydrides, imides and amides. Exchange of nitrogen and hydrogen within the bulk and with the gas phase seems fast, which are important characteristics in the field of catalysis.

Publications related to Hydrides

Verbraeken, M.C., Suard, E., Irvine, J.T.S.,
Journal of Solid State Chemistry, vol. 184, 2011, p. 2088 – 2096,
“Order and disorder in Ca2ND0.90H0.10: a structural and thermal study”
DOI: 10.1016/j.jssc.2011.05.062

Verbraeken, M.C., Suard, E., Irvine, J.T.S.,
Journal of Materials Chemistry, vol. 19 (18), 2008, p. 2766 – 2770,
“Structural and electrical properties of calcium and strontium hydrides”
DOI: 10.1039/B820173K