Oxidative transformation of intermetallic nanoparticles: An alternative pathway to metal/oxide nanocomposites, textured ceramics, and nanocrystalline multimetal oxides

A new low-temperature strategy is described for the synthesis of nanocrystalline multimetal oxides. In this approach, intermetallic nanoparticles synthesized via a modified polyol process are used as reactive precursors that help to define both the composition and morphology of multimetal oxides via a two-step thermal oxidation process. We use Bi2PdO4 and Bi2Pt2O7 as model systems for elaborating this new synthetic strategy. For Bi2PdO4, intermetallic Bi2Pd nanocubes are thermally oxidized to form a Bi2O3/Pd nanocomposite, which transforms to textured Bi2PdO4 upon further heating in O-2. Bi2Pt2O7 is formed using a similar strategy involving the thermal oxidation of intermetallic Bi-Pt nanoparticles. The reaction pathway is established using a combination of X-ray diffraction analysis, transmission electron microscopy, thermogravimetric analysis, and energy-dispersive spectrometry element mapping data. Given the growing number of intermetallic compounds that are accessible as nanoparticles, this strategy has the potential to yield many other mixed metal oxides as nanocrystalline powders. Supported nanoparticle catalyst systems and textured ceramics are also accessible by exploiting the reaction pathway.