Journal
APPLIED SURFACE SCIENCE
Volume 329, Issue -, Pages 83-86Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2014.12.110
Keywords
Graphene oxide; Alkaline solution; Flocculation; Acid base interaction
Categories
Funding
- National Science Foundation of China [51262012]
- Foundation of Jiangxi Science and Technology Committee [20133ACB20007, 20114BAB206022]
- Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences [KLICM-2014-07]
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In the modified Hummers method for preparing graphene oxide, the yellow slurry can be obtained. After filtering through a quantitative filter paper, the strong-acid filtrate containing the unprecipitated nano graphene oxide was gained. The corresponding filtrate was added gradually with an alkaline (NaOH or KOH) solution at room temperature. The unprecipitated nano graphene oxide could undergo fast aggregation when the pH value of the filtrate was about 1.7 and formed the stable floccules. X-ray diffraction analysis shows the dominant peak of the floccules is about 11 degrees, which accords to the peak of graphene oxide. Spectra of X-ray photoelectron spectroscopy confirm the presence in the floccules of an abundance of oxygen functional groups and the purified graphene oxide floccules can be obtained. Atomic force microscopy measurement shows the graphene oxide floccules consists of sheet-like objects, mostly containing only a few layers (about 5 layers). Zeta potential analysis demonstrates the surface charge of the graphene oxide is pH-sensitive and its isoelectric point is similar to 1.7. The flocculation mechanism of graphene oxide ascribes to the acid-base interaction with the surface functional groups of the carbon layers. (C) 2014 Elsevier B.V. All rights reserved.
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