2020 Fiscal Year Research-status Report
Revealing Lattice Defect Restoration in Graphene Oxide using Tip-Enhanced Raman Spectroscopy
| Project/Area Number |
20K15132
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| Research Institution | Toyota Technological Institute |
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Principal Investigator |
kanishka DeSilva 豊田工業大学, 工学(系)研究科(研究院), ポストドクトラル研究員 (20870182)
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| Project Period (FY) |
2020-04-01 – 2022-03-31
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| Keywords | Graphene oxide / Reduction / TERS / C-AFM / Tiling method / CH4 plasma |
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| Outline of Annual Research Achievements |
This research focuses on revealing the reduction and lattice defect restoration of graphene oxide (GO) by nanoscale imaging and characterization by tip enhanced Raman spectroscopy (TERS) and atomic force microscopy (AFM). During the FY2020, we basically focused on the fabrication of materials and succeeded in the following steps. (1) Fabrication of continuous monolayer graphene oxide films on SiO2/Si and quartz substrates. Here we employed an easy method, reported as the tiling of 2D materials. (2) Reduction and restoration of GO films by thermal annealing in the presence of different alcohols and methane plasma (CH4) to obtain highly conducting transparent monolayer reduced GO (RGO) films. (3) Fabrication of cantilevers for TERS measurements via physical and chemical treatments with good enhancement that can be used in both gap mode and non-gap mode. However, further improvement and TERS measurements are still going on.
Moreover, conductive atomic force microscopy (C-AFM) was employed to characterize the local conductivity of the RGO films, which gives information regarding the current distribution through the film in at a nanoscale.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
This research basically consists of 2 things; fabrication of the materials and nanoscale characterization. Both were carried out simultaneously. An important thing we achieved is that the fabrication of TERS tips by ourselves with good enhancement. Another thing is that the optimization of the fabrication of continuous monolayer GO films via a simple spin-coating method allowing us to obtain highly transparent films and ease of nanoscale characterization.
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| Strategy for Future Research Activity |
Although the homemade TERS tips can also be used in non-gap mode, to get better enhancements it is necessary to use plasmonic substrate like Au. We observed that during annealing GO deposited on Au coated mica or Si substrates, the Au structure changes making it difficult for the characterization. So developed a method to transfer RGO from SiO2/Si substrates to Au/mica substrates via a stamping method. This is an ongoing work. Also, the stability, reusability, and durability of the homemade TERS tips are in progress.
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| Causes of Carryover |
We used the budget allocated for FY2020 as planned. Some of the experiments were succeeded so the money allocated for them could be used in further improvements of the experiments, which are planed for FY2021. Also, due to the travel restrictions caused by the pandemic situation, all the conferences were held online. Therefore, there is a surplus in the budget. However, that will be used in designing and making the new CVD device.
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