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The shape-controlled conversion of a diverse library of rhodium nanocrystal shapes into dense and hollow [Rh.sub.2]P nanocrystals is described.

A new strategy is described for synthesizing nanostructures of transition metal phosphides, which has used the conversion of preformed metal nanoparticles into metal phosphides by solution-mediated reaction with trioctyphosphine (TOP). The results have shown that in addition to its utility for accessing transition metal phosphides using a highly robust method, various aspects of nanostructure can be influenced by controlling critical aspects of the metal nanoparticle precursors.

Abstract: A solution precursor route has been used to synthesize a series of nanocrystalline rare-earth borates. Amorphous precursor powders are precipitated during an aqueous reaction between RE 3+ and NaBH4, and the isolated powders can be annealed in air at 700°C to form YBO3, NdBO3, SmBO3, EuBO3, GdBO3, and HoBO3. YBO3:Eu formed using this strategy shows red-orange emission properties that are similar to high-quality nanocrystals prepared by other methods. The materials have been characterized by FTIR spectroscopy, powder XRD, SEM, DSC, UV–Vis fluorimetry, and TEM with EDS and element mapping. [Copyright &y& Elsevier]

When reacted with trioctylphosphine at ~360 °C, rhodium nanocrystals convert to rhodium phosphide (Rh2P) nanocrystals. Careful control over synthetic variables, such as temperature, stabilizing ligands, and cosolvents, can result in Rh2P nanocrystals with shapes that reflect the Rh nanocrystal templates. Accordingly, Rh nanocrystals with multipod, cube- and triangle-derived shapes convert to Rh2P nanocrystals that maintain the shape of their Rh precursors. Both dense and hollow Rh2P nanocrystals can be generated using a single unified chemical conversion strategy. These empirical guidelines for generating a morphologically diverse library of Rh2P nanocrystals provide important insights into shape conservation using nanocrystal templates and will likely be portable to other multielement systems for which rigorous shape-controlled synthesis remains challenging. [ABSTRACT FROM AUTHOR]