Studies on the synthesis, characterization and hydrogenation behaviour of new Zr 1− xMm x(Cr 0.8Mo 0.2) 2 AB 2-type hydrogen storage materials

Abstract

This paper deals with the improvement in the hydrogenation behaviour of ZrCr 2 type alloys through substitutions at both the Zr and Cr sites. It has been found that the alloy Zr 1− x Mm x (Cr 1− y Mo y ) 2 exhibits better hydrogen storage capacity and kinetics as compared to the parent alloy ZrCr 2 or its variant Zr(Cr 1− y Mo y ) 2. The optimum material has been found to correspond to Zr 0.93Mm 0.07(Cr 0.8Mo 0.2) 2 which shows a high hydrogen storage capacity of ∼1.8 wt.% under ambient conditions. This is the highest storage capacity known so far for the ZrCr 2 type hydrogen storage system. It should be pointed out that the storage capacity reported previously in the literature for the optimum material Zr(Cr 0.8Mo 0.2) 2 has a value of 1.53 wt.% only. In addition to the higher storage capacity, the material Zr 0.93Mm 0.07(Cr 0.8Mo 0.2) 2 also exhibits kinetics (5×10 −4 m 3/s/kg) that are faster than the known kinetics (3×10 −4 m 3/s/kg) for the ZrCr 2 storage system. A correlation between structural/microstructural characteristics and the improved hydrogenation behaviour (higher storage capacity and faster kinetics) has been outlined.