Article

Thermolytic Transformation of Organometallic Polymers Containing the Cr(CO)5 Precursor into Nanostructured Chromium Oxide

Journal of Cluster Science (Impact Factor: 1.36). 12/2005; DOI: 10.1007/s10876-005-0033-x
Source: OAI

ABSTRACT Thermal treatment in air of the organometallic polymer{[NP(O2C12H8)]0.8[NP(OC6H4CH2CN • [Cr(CO)5]0.13)2]0.18}n (1) results in the formation of nanometer-size metal oxide particles. Cr particles in the 35–85 nm range, mostly 54 nm, immersed in an phosphorus oxides matrix were found. ATG studies in air suggest that the formation of the nanostructures occurs in four steps, the first involving loss of the carbonyl groups of the Cr(CO)5 fragment. The following steps involve the oxidation of the organic matter and finally the oxidation of the chromium to give the pyrolytic product. The use of these kinds of organometallic polymers as precursors for a general and potential new route to materials having metal/metal oxide nanostructures is discussed.

0 Followers
 · 
63 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cyclotriphosphazene is used as a sacrificial solid-state template to synthesize a range of Ag and Pd nanoparticles with diverse geometries by thermal treatment using MLn/N3P3(O2C12H8)(3) mixtures. The Pd and Ag nanoparticles are synthesized by solid-state pyrolysis of AgPPh3[CF3SO3]/N3P3(O2C12H8)(3) and PdCl2/N3P3(O2C12H8)(3) mixtures with molar relationships of 1:1, 1:5 and 1:10 respectively, in air and at 800 degrees C. The morphology of the as-prepared nanoparticles is found to depend on the molar ratio of the precursor mixture, the preparation method and of the nature of the metal. Ag and Pd, microcrystals were thermally grown on Si from the respective 1:1 precursors while that metal foams were grown from 1:5 ratios precursors on SiO2 wafers. High resolution transmission electron microscopy investigations reveal in most cases small crystals of Pd. HRSTEM measurements indicate that the formation of the Pd and Ag nanoparticles occurs through a phase demixing and dewetting mechanism. This approach has potential to be a useful and facile method to prepare metallic nanoparticles without requiring solutions or surfactants for application in electronic, catalytic and sensor materials and devices.
    Materials Chemistry and Physics 12/2013; 143(1):124-132. DOI:10.1016/j.matchemphys.2013.08.034 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pyrolysis of molecular precursors containing vanadium organometallic and cyclic phosphazene affords mixtures of nanostructured vanadium oxides and pyrophosphates. The products from the molecular precursor [N3P3(OC6H5)5OC5H4N·Cp2VCl][PF6], and of the mixtures Cp2VCl2/N3P3(OC6H4CHO)6 and Cp2VCl2/[NP(O2C12H8)]3 in several relationships 1:1, 1:3, 1:5 and 1:10, pyrolyzed under air and at 400 °C and 600 °C, give mixtures mainly V2O5 and VO(PO3)2. Varied morphologies depending on the molecular or mixture precursors and of the temperature used were observed. Nanowires with diameters of approximate 40 nm were observed for the 1:5 Cp2VCl2/[NP(O2C12H8)]3 mixture pyrolyzed at 400 °C, while the same mixture pyrolyzed at 600 °C, affords xerogels of V2O5. The products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), infra-red (IR) spectroscopy and X-ray diffraction (XRD). The preparation method constitutes a novel one-pot solid-state way to nanostructured materials with potential applications both in oxidative dehydrogenation of light hydrocarbons with V2O5, as well as alkenes oxidations with VO(PO3)2.
    Journal of Cluster Science 12/2011; 22(4). DOI:10.1007/s10876-011-0415-1 · 1.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanostructured copper containing materials of CuO, Cu3(PO4)3 and Cu2P2O7 have been prepared by solid-state pyrolysis of molecular CuCl2·NC5H4OH (I), CuCl2·CNCH2C6H4OH (II), oligomeric [Cu(PPh3)Cl]4 (III), N3P3[OC6H4CH2CN·CuCl]6[PF6] (IV), N3P3[OC6H5]5[OC5H4N·Cu][PF6] (V), polymeric chitosan·(CuCl2)n (VI) and polystyrene-co-4-vinylpyridine PS-b-4-PVP·(CuCl2) (VII) precursors. The products strongly depend on the precursor used. The pyrolytic products from phosphorus-containing precursors (III), (IV) and (V) are Cu phosphates or pyrophosphates, while non-phosphorous-containing precursors (VI) and (VII), result in mainly CuO. The use of chitosan as a solid-state template/stabilizer induces the formation of CuO and Cu2O nanoparticles. Copper pyrophosphate (Cu2P2O7) deposited on Si using (IV) as the precursor exhibits single-crystal dots of average diameter 100nm and heights equivalent to twice the unit cell b-axis (1.5–1.7nm) and an areal density of 5.1–7.7Gigadots/in.2. Cu2P2O7 deposited from precursor (VI) exhibits unique labyrinthine high surface area deposits. The morphology of CuO deposited on Si from pyrolysis of (VI) depends on the polymer/Cu meta ratio. Magnetic measurements performed using SQUID on CuO nanoparticle networks suggest superparamagnetic behavior. The results give insights into compositional, shape and morphological control of the as-formed nanostructures through the structure of the precursors.
    Inorganica Chimica Acta 11/2011; 377(1):5-13. DOI:10.1016/j.ica.2011.07.003 · 2.04 Impact Factor

Preview

Download
0 Downloads
Available from