NANOMATERIALS

Repacking rhodium

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Science  27 Jan 2017:
Vol. 355, Issue 6323, pp. 364-365
DOI: 10.1126/science.355.6323.364-d

Rhodium packs as a face-centered cubic (fcc) crystal, but Huang et al. now report two routes for creating hexagonally close-packed (hcp) Rh as nanoparticles. In transmission electron microscopy studies of free-standing Rh monolayers, they observed irradiation-induced formation of hcp nanoparticles. A solvothermal synthesis route also produced hcp nanoparticles that in some cases had surface regions with fcc structure. First-principles calculations indicate that the hcp nanoparticles are stabilized relative to fcc crystals by having a lower surface energy. The hcp nanoparticle lattice is also expanded by 6%, versus a 0.4% expansion for a bulk crystal, and this expansion affects electronic properties and likely increases surface reactivity.

J. Am. Chem. Soc. 10.1021/jacs.6b09730 (2017).

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