Greatly enhanced adsorption and catalytic activity of Au and Pt clusters on defective graphene.

Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore.
The Journal of Chemical Physics (Impact Factor: 3.12). 05/2010; 132(19):194704. DOI: 10.1063/1.3427246
Source: PubMed

ABSTRACT We report an investigation on CO oxidation catalyzed by Au(8) or Pt(4) clusters on defective graphene using first-principles approach based on density functional theory. The simplest single-carbon-vacancy defect on graphene was found to play an essential role in the catalyzed chemical reaction of CO oxidation. When supported on a defect-free graphene sheet, the reaction barrier of CO oxidation catalyzed by Au(8) (Pt(4)) clusters was estimated to be around 3.0 eV (0.5 eV), and when adsorbed on defective graphene, the reaction barrier was greatly reduced to around 0.2 eV (0.13 eV).

  • [Show abstract] [Hide abstract]
    ABSTRACT: Graphene nanosheet-supported ultrafine metal nanoparticles encapsulated by thin mesoporous SiO2 layers were prepared and used as robust catalysts with high catalytic activity and excellent high-temperature stability. The catalysts can be recycled and reused in many gas- and solution-phase reactions, and their high catalytic activity can be fully recovered by high-temperature regeneration, should they be deactivated by feedstock poisoning. In addition to the large surface area provided by the graphene support, the enhanced catalytic performance is also attributed to the mesoporous SiO2 layers, which not only stabilize the ultrafine metal nanoparticles, but also prevent the aggregation of the graphene nanosheets. The synthetic strategy can be extended to other metals, such as Pd and Ru, for preparing robust catalysts for various reactions.
    Angewandte Chemie International Edition 11/2013; · 11.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The stability of doped graphene sheets and a catalytic platinum (Pt) film on the doped sheets was investigated for a variety of dopants, using the first-principles calculations in the density functional theory. It was shown that the doping (dopant-substitution) energy increases as the differences of atomic radius and valency increase between the dopant atom and the host carbon atom. On the other hand, the adsorption energy of the Pt film becomes larger on doped graphene sheets, compared to that on undoped graphene sheet. We found a strong correlation between the adsorption and doping energies: the adsorption energy increases as the doping energy increases. This correlation occurs because the Pt-film adsorption partially releases hetero-valency-induced doping-energy loss through electron redistribution and atom-position change. We showed that cation–anion dopant pairs in the graphene sheet are also effective to stabilize adsorbed Pt films.
    Surface Science. 01/2014; 621:7–15.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate efficient physical functionalization of single layer graphene with Au nanoparticles mediated by in-plane defects in graphene grown by a chemical vapor deposition technique. The effect of ultra thin Au layer on the single layer, bi layer and few layer graphene with intrinsic defects was studied by resonance Raman spectroscopy and high resolution transmission electron microscopy (HRTEM). We observed a striking enhancement in the intensity of sharp D and D' bands after sputter deposition of ultra thin Au layer on graphene. In contrast, G and 2D bands shows lower enhancement in intensity and change in line width due to the charge transfer from Au to the graphene and strong interaction between the Au and graphene layers, respectively. X-ray photo electron spectroscopy (XPS) analysis shows 40% decrease in integrated intensity ratio of sp3 and sp2 bands in C−1s spectra after Au functionalization indicating bonding of Au atoms preferentially at the defect sites in graphene. This was further substantiated by HRTEM imaging and position dependent Raman spectral line shape analysis. The calculations of inter defect distance and areal defect density from the Raman analysis on the graphene-Au hybrid are in close agreement with the HRTEM analysis. Further, Raman spectral line shape dependence of Au functionalization on the number of layers in graphene reveals that Au functionalised single layer graphene behaves like a pristine bilayer graphene due to strong interaction between Au and graphene layer. These results open up possibilities for efficient physical functionalization of graphene with foreign atoms through defect engineering for novel applications of graphene in catalysis, biosensors, optoelectronic and photonic devices.
    The Journal of Physical Chemistry C 06/2014; · 4.84 Impact Factor

Full-text (2 Sources)

Available from
May 31, 2014