Effect of the Inherent Structure of Rh Nanocrystals on the Hydriding Behavior under Pressure.

Tailoring the inherent structure of materials is an effective way to improve the hydrogen storage capacity of metal materials. In this work, we report the effect of rhodium (Rh) nanocrystals (NCs) on the hydrogenation reaction. We found that Rh NCs could form rhodium monohydride (RhH) at a lower pressure than the bulk Rh because of its high specific surface area and structure defects. In addition, Rh NCs in the form of icosahedrons exhibited a much higher hydrogen absorption efficiency than Rh nanocubes. Furthermore, much smaller irregular Rh nanoparticles are even partially converted to RhH at lower pressure because of the nanosize effect. We thus believe that it is possible to design materials with excellent hydrogen storage properties under mild conditions.