Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts

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Science  20 May 2016:
Vol. 352, Issue 6288, pp. 974-978
DOI: 10.1126/science.aad8471
  • Fig. 1 High-temperature self-assembly of NM monolayers on TMC cores.

    (A to D) Schematic representations and corresponding STEM images of (A) silica-encapsulated (NH4)2PtCl6/WOx NPs synthesized in a one-pot reactor at room temperature and subsequently heated to (B) 200°C, (C) 600°C, and (D) 900°C in a CH4/H2 atmosphere. ΔT, temperature change. (E) STEM image, EDX map, and line scan (Pt signal in green, W signal in red) of a resulting core-shell Pt/WC NP and a STEM image of Pt/WC formulated on a carbon black support after silica removal.

  • Fig. 2 Experimental corroboration of core-shell structure.

    (A) PXRD diffractograms of PtC-S and Ptdirect compared to Ptcomm. A.U., arbitrary units. (B) XPS comparison of the C 1s, Pt 4f, and W 4f signals of PtC-S and Ptdirect. (C) TEM images of PtC-S, PtRuC-S, and Ptdirect. (D) STEM and EDX maps of PtRuC-S.

  • Fig. 3 Electrochemical activity and stability of PtC-S and PtRuC-S compared to commercial catalysts.

    (A) HOR/HER Tafel plots. RHE, reversible hydrogen electrode. (B) HOR LSVs with and without CO contamination. (C) LSVs and (D) CVs for MOR normalized by CO-ECSA roughness factors. (E) Steady-state specific activity at fixed potentials after stability cycling and regeneration in alkaline media. (F) TEM images of PtC-S and PtRuC-S and a STEM image with EDX map of a PtC-S NP after stability cycling.

  • Fig. 4 Experimental exploration of various core-shell NM/TMC architectures.

    (A) PXRD diffractograms of NM/TiWC NPs of various sizes, compositions, and NM coverages. (B) STEM image and EDX maps of carbon-supported Pt/(CuW)2C NPs. (C) PXRD diffractograms of Pt monolayers on various bimetallic semicarbide core NPs. (D) XPS spectra of (a to c) Au/TiWC NPs, (d to f) Pt/TiWC NPs, and (g and h) PtAu/TiWC NPs with submonolayer, monolayer, and multilayer NM shell thicknesses. The asterisks in (D) mark the Pt2+ signal.

Supplementary Materials

  • Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts

    Sean T. Hunt, Maria Milina, Ana C. Alba-Rubio, Christopher H. Hendon, James A. Dumesic, Yuriy Román-Leshkov

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S33
    • Tables S1 to S5
    • References (33–61 )

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