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|
| Type |
Poster Presentation |
| Area |
Physical Chemistry |
| Room No. |
Exhibition Hall 2+3 |
| Time |
10월 20일 (금요일) 13:00~14:30 |
| Code |
PHYS.P-123 |
| Subject |
Oxygen/Water Redox Couple Modulating Interfacial Charge Transfer of Graphene [우수포스터상] |
| Authors |
Kwanghee Park, Sunmin Ryu*
Department of Chemistry, Pohang University of Science and Technology, Korea
|
| Abstract |
Low dimensional carbon materials in the ambient conditions undergo spontaneous hole doping, the detailed mechanism of which has yet to be revealed. In this work, we propose a mechanism based on a redox couple of O2/H2O and verify it for two model systems: i) annealing-induced charge transfer of graphene/SiO2 in air and ii) acid-induced charge transfer of graphene/SiO2 in water. Raman spectroscopy and water contact angle measurements were used to quantify the charge density in graphene and hydrophilicity of substrates, respectively. First, thermal annealing enhances the degree of the charge transfer in silica-supported graphene exposed to oxygen and water vapor. Mechanically exfoliated graphene samples on silicon dioxide substrates were annealed at various temperatures in a range of 100 ~ 1000 oC to induce the hole doping. While the annealing-induced charge density of graphene increased with increasing annealing temperature up to 700 oC, it decreased as increasing the temperature further higher. Water contact angle measurements showed that the charge transfer rate is proportional to the hydrophilicity of the substrates. Graphene samples prepared in a low humidity condition lead to significantly decreased charge transfer suggesting that water contained between graphene and substrate plays a key role. For the second system, we found that graphene in acidic solution is hole-doped and the responsible charge transfer requires dissolved oxygen. The proposed mechanism will be discussed to explain the experimental results observed for the two model systems. |
| E-mail |
kwanghee@postech.ac.kr |
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120th General Meeting of the KCS