Research ArticleAPPLIED SCIENCES AND ENGINEERING

Finely controlled multimetallic nanocluster catalysts for solvent-free aerobic oxidation of hydrocarbons

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Science Advances  26 Jul 2017:
Vol. 3, no. 7, e1700101
DOI: 10.1126/sciadv.1700101
  • Fig. 1 Synthetic methods for MNCs in solution.

    (A) Typical synthetic method for MNCs resulting in a statistical distribution in size and metal composition. (B) New synthetic approach using a dendrimer template whose coordination sites have a basicity gradient.

  • Fig. 2 Molecular structure of TPM-DPA G4.

    The strength of the red color of the nitrogen atoms expresses the layer-by-layer electron density gradient.

  • Fig. 3 Preparation of MNCs supported on GMCs.

    (A) Schematic representation of the synthesis of Cu32Pt16Au12@TPM-DPA G4/GMC by layer-by-layer stepwise complexation with metal ions followed by chemical reduction. (B) Atomic resolution high-magnification STEM images of MNCs on GMCs.

  • Fig. 4 Solvent-free aerobic oxidation of hydrocarbons.

    Comparison of the catalytic activities of various catalysts based on TOF, calculated by turnover number of conversion from indane to indanone per total metal atoms (Cu, Pd, Pt, and Au) per hour. (A) Open air. (B) O2 1 atm. The subscripts on the chemical symbols mean the nominal equivalents of respective elements to the molar amount of the dendrimer.

  • Scheme 1 Plausible mechanisms.

    The steps in aerobic oxidation of a benzylic C-H bond catalyzed by MNCs. Metal cat, metal catalyst.

  • Scheme 2 Plausible mechanisms.

    The steps in aerobic oxidation of a benzylic C-H bond catalyzed by MNCs.

  • Scheme 3 Plausible mechanisms.

    The steps in aerobic oxidation of a benzylic C-H bond catalyzed by MNCs.

  • Scheme 4 Plausible mechanisms.

    The steps in aerobic oxidation of a benzylic C-H bond catalyzed by MNCs.

  • Fig. 5 Aerobic oxidation of indane at room temperature.

    TOFs of indane oxidation catalyzed by MNCs at room temperature in open air. The reactions were carried out without solvents in the presence of a catalytic amount of a radical initiator (TBHP). The subscripts on the chemical symbols mean the nominal equivalents of respective elements to the molar amount of the dendrimer.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700101/DC1

    fig. S1. UV-vis spectral titration of TPM-DPA G4 on the addition of AuCl3, PtCl4, and CuCl2.

    fig. S2. Durability of Cu32Pt16Au12@TPM-DPA G4/GMC catalysts.

    fig. S3. Confirmation of coexistence of Cu, Pt, and Au atoms by STEM-EDX chemical mappings in Cu32Pt16Au12@TPM-DPA G4/GMC.

    fig. S4. Confirmation of coexistence of Cu, Pt, and Au atoms by STEM-EDX analysis in Cu32Pt16Au12@TPM-DPA G4/GMC.

    fig. S5. XPS analysis of various NCs at Cu 2p region.

    fig. S6. XPS analysis of various NCs at Pt 4f region.

    fig. S7. XPS analysis of various NCs at Au 4f region.

    fig. S8. XPS analysis of Cu NCs at Cu 2p region.

    fig. S9. XPS analysis of Pt NCs at Pt 4f region.

    fig. S10. XPS analysis of Au NCs at Au 4f region.

    fig. S11. XAFS analysis for Cu atoms on MNCs.

    fig. S12. XAFS analysis for Pt atoms on MNCs.

    fig. S13. XAFS analysis for Au atoms on MNCs.

    fig. S14. Products ratio of the aerobic oxidation reactions using various NC catalysts.

    fig. S15. Aerobic oxidation of tetralin using a commercially available Pt on carbon catalyst or MNCs.

    fig. S16. The effects of Cu-Pt ratio on catalytic activities of oxidation reaction.

    scheme S1. Schematic representation of complexation of TPM-DPA G4 with AuCl3, PtCl4, and CuCl2.

    table S1. Oxidation resistance of Cu and Cu-M alloy NCs in air.

    table S2. Curve fitting results of Cu32Pt16Au12@TPM-DPA G4/GMC for Cu K-edge, Pt L3 and Au L3-edge EXAFS spectra.

    table S3. Substrate generality in the aerobic oxidation using MNC catalyst.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. UV-vis spectral titration of TPM-DPA G4 on the addition of AuCl3, PtCl4, and CuCl2.
    • fig. S2. Durability of Cu32Pt16Au12@TPM-DPA G4/GMC catalysts.
    • fig. S3. Confirmation of coexistence of Cu, Pt, and Au atoms by STEM-EDX chemical mappings in Cu32Pt16Au12@TPM-DPA G4/GMC.
    • fig. S4. Confirmation of coexistence of Cu, Pt, and Au atoms by STEM-EDX analysis in Cu32Pt16Au12@TPM-DPA G4/GMC.
    • fig. S5. XPS analysis of various NCs at Cu 2p region.
    • fig. S6. XPS analysis of various NCs at Pt 4f region.
    • fig. S7. XPS analysis of various NCs at Au 4f region.
    • fig. S8. XPS analysis of Cu NCs at Cu 2p region.
    • fig. S9. XPS analysis of Pt NCs at Pt 4f region.
    • fig. S10. XPS analysis of Au NCs at Au 4f region.
    • fig. S11. XAFS analysis for Cu atoms on MNCs.
    • fig. S12. XAFS analysis for Pt atoms on MNCs.
    • fig. S13. XAFS analysis for Au atoms on MNCs.
    • fig. S14. Products ratio of the aerobic oxidation reactions using various NC catalysts.
    • fig. S15. Aerobic oxidation of tetralin using a commercially available Pt on carbon catalyst or MNCs.
    • fig. S16. The effects of Cu-Pt ratio on catalytic activities of oxidation reaction.
    • scheme S1. Schematic representation of complexation of TPM-DPA G4 with AuCl3, PtCl4, and CuCl2.
    • table S1. Oxidation resistance of Cu and Cu-M alloy NCs in air.
    • table S2. Curve fitting results of Cu32Pt16Au12@TPM-DPA G4/GMC for Cu K-edge, Pt L3 and Au L3-edge EXAFS spectra.
    • table S3. Substrate generality in the aerobic oxidation using MNC catalyst.

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