Solar photoconversion using graphene/TiO 2 composites: Nanographene shell on TiO 2 core versus TiO 2 nanoparticles on graphene sheet

Hyoung Il Kim, Gun Hee Moon, Damián Monllor-Satoca, Yiseul Park, Wonyong Choi

Research output: Contribution to journalArticlepeer-review

254 Citations (Scopus)

Abstract

Size controlled nanographene oxides (NGOs; <50 nm) were prepared by a two-step oxidation process and NGOs were self-assembled with TiO 2 nanoparticles to form the core/shell structure. Nanosized GO-coated TiO 2 nanoparticles (NGOTs) were then reduced by a photocatalytic process under UV irradiation to obtain graphene-coated TiO 2. This is clearly different from the typical graphene/TiO 2 composite with the particles-on-a-sheet geometry and is the first study on the core/shell structure of its kind. The physicochemical properties of NGOs and the reduced NGOTs (r-NGOTs) were characterized by various analytical and spectroscopic methods (AFM, FT-IR, XPS, TEM, EELS, etc.). The photocatalytic and photoelectrochemical activities of r-NGOT were compared with a composite of r-GO/TiO 2 that has TiO 2 nanoparticles loaded on a larger graphene sheet (r-LGOT). The photocatalytic production of hydrogen was measured in the aqueous suspension of the composite photocatalyst under UV irradiation (λ > 320 nm), and the photoelectrochemical behaviors were characterized using the electrode coated with the composite photocatalyst. The rates of H 2 production and photocurrent generation were higher with r-NGOT than r-LGOT, which indicates that the presence of r-GO shell on the surface of TiO 2 facilitates the interfacial electron transfer. The direct contact between r-NGO and TiO 2 is maximized in r-NGOT by retarding the charge recombination and accelerating the electron transfer. The geometry of the core/shell structure should be effective in the design of a graphene/TiO 2 composite for solar conversion applications.

Original languageEnglish
Pages (from-to)1535-1543
Number of pages9
JournalJournal of Physical Chemistry C
Volume116
Issue number1
DOIs
Publication statusPublished - 2012 Jan 12

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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