Investigations into the interaction between hydrogen and calcium nitride

Abstract

The interaction between hydrogen and α-Ca₃N₂ has been investigated by temperature programmed adsorption–desorption and pressure–composition (P–C) isotherms and also by X-ray powder diffraction. We find that hydrogen adsorption by Ca₃N₂ begins at temperatures around 300 °C. Approximately 3.5 H atoms can be adsorbed by one Ca₃N₂ molecule. Only half of the adsorbed hydrogen can be desorbed at temperatures above 350 °C. Addition of CaH₂ enhances the reversibility of H-adsorption in the Ca₃N₂ sample. As demonstrated in the present work, almost all of the hydrogen adsorbed by the Ca₃N₂–CaH₂ sample (molar ratio 1 ∶ 1) can be released with Ca₂NH as the final product.