Growth and Stability of Titanium Dioxide Nanoclusters on Graphene/Ru(0001)
[3];
[1];
[4]
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States
- Fundamental and Computational Sciences Directorate and Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University, A-8010 Graz, Austria
- Fundamental and Computational Sciences Directorate and Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99163, United States
Titanium dioxide/graphene composites have recently been demonstrated to improve the photocatalytic activity of TiO2 in visible light. To better understand the interactions of TiO2 with graphene we have investigated the growth of TiO2 nanoclusters on single-layer graphene/Ru(0001) using scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). Deposition of Ti in the O2 background at 300 K resulted in the formation of nanoclusters nucleating on intrinsic defects in the graphene (Gr) layer. The saturation nanocluster density decreased as the substrate temperature was increased from 300 to 650 K, while deposition at 700 K resulted in the significant etching of the Gr layer. We have also prepared nanoclusters with Ti2O3 stoichiometry using lower O2 pressures at 650 K. Thermal stability of the TiO2 nanoclusters prepared at 300 K was evaluated with AES and STM. No change in oxidation state for the TiO2 nanoclusters or etching of the Gr layer was observed up to ~900 K. Annealing studies characterized using STM revealed that cluster ripening proceeds via a Smoluchowski mechanism below 800 K and that Ostwald ripening dominates above 800 K. At even higher temperatures, the nanoclusters undergo reduction to TiOx (x ≈ 1 - 1.5) which is accompanied by oxidation and etching of the Gr. Our studies demonstrate that highly thermally stable TiOx nanoclusters of controlled composition and morphology can be prepared on Gr supports.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1438982
- Report Number(s):
- PNNL-SA-126878; 49642; KC0302010
- Journal Information:
- Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry, Vol. 122, Issue 2; ISSN 1520-6106
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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