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This content will become publicly available on June 8, 2017

Title: Nanoscale Silicon as a Catalyst for Graphene Growth: Mechanistic Insight from in Situ Raman Spectroscopy

Nanoscale carbons are typically synthesized by thermal decomposition of a hydrocarbon at the surface of a metal catalyst. Whereas the use of silicon as an alternative to metal catalysts could unlock new techniques to seamlessly couple carbon nanostructures and semiconductor materials, stable carbide formation renders bulk silicon incapable of the precipitation and growth of graphitic structures. In this article, we provide evidence supported by comprehensive in situ Raman experiments that indicates nanoscale grains of silicon in porous silicon (PSi) scaffolds act as catalysts for hydrocarbon decomposition and growth of few-layered graphene at temperatures as low as 700 K. Self-limiting growth kinetics of graphene with activation energies measured between 0.32–0.37 eV elucidates the formation of highly reactive surface-bound Si radicals that aid in the decomposition of hydrocarbons. Nucleation and growth of graphitic layers on PSi exhibits striking similarity to catalytic growth on nickel surfaces, involving temperature dependent surface and subsurface diffusion of carbon. Lastly, this work elucidates how the nanoscale properties of silicon can be exploited to yield catalytic properties distinguished from bulk silicon, opening an important avenue to engineer catalytic interfaces combining the two most technologically important materials for modern applications—silicon and nanoscale carbons.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [2] ;  [1]
  1. Vanderbilt Univ., Nashville, TN (United States)
  2. Air Force Research Lab. (AFRL), Wright-Patterson AFB, OH (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
Publication Date:
OSTI Identifier:
1271889
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 120; Journal Issue: 26; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY