[6a-S44-1~10] 9.2 Nanowires and Nanoparticles

[6a-S44-1] Size-dependent hydrogen-storage properties in Rh nanoparticles, revealed by synchrotron-based X-ray techniques: HEXRD, EXAFS

〇Chulho Song¹, Yang Anli¹, Kumara L. S. R.¹, Hiroi Satoshi¹, Kusada Kohei², Kobayashi Hirokazu², Kitagawa Hiroshi² (1.NIMS/SPring-8, 2.Kyoto Univ.)

Keywords:Hydrogen-storage ability, Rh nanoparticles

We have investigated the structural characterization of Rh NPs with various particle sizes (2.4, 4.0, 7.1, 10.5 nm), using the synchrotron based X-ray techniques. To unveil the origin of their hydrogen absorption ability, we used the particle size dependence of lattice distortion, coordination number, mean-square displacement and volume fraction of cavities for Rh NPs. From the HEXRD and EXAFS, It is found that the lattice distortion/mean-square displacement increase and coordination number decreases with decreasing the particle size. This result suggested that the hydrogen absorption ability of Rh NPs is more closely related to mean-square displacement for local structure (EXAFS) than that for mean structure (HEXRD). From the cavity analysis, we confirmed that the cavities are distributed over the whole particle and hydrogen can be trapped on the entire volume for the smallest Rh NPS. The obtained structural information will contribute to designing and improving the functionality of nano-sized metals.