研究目的
Investigating the pH- and potential-dependence of the interfacial water structure in contact with a chemical vapor deposited (CVD)-grown graphene surface to understand the graphene-water interface better.
研究成果
The SFG signal from the interfacial water molecules at the graphene layer is dominated by the underlying substrate, and there are water molecules between the graphene and the hydrophilic supporting substrate. The interface is more complex than just graphene-water, as water also intercalates between the substrate and graphene. Future studies could explore different thin layer materials that might be more stable and easier to produce than graphene.
研究不足
The presence of water molecules between the graphene and the substrate complicates the interpretation of the SFG signal. Sample variations and potential-induced changes in the graphene layers make it difficult to draw definitive conclusions about the interfacial water structure. The experiments also induced changes in the graphene layers, indicating that the samples were not fully stable under electrochemical treatment.
1：Experimental Design and Method Selection:
Sum-frequency generation (SFG) spectroscopy was used to investigate the interfacial water structure at the graphene-water interface. The methodology included designing a spectro-electrochemical cell for measuring SFG spectra while applying a potential.
2：Sample Selection and Data Sources:
CVD-grown graphene on copper foil was transferred onto CaF2 or SiO2 substrates. The samples were characterized using AFM, Raman spectroscopy, and optical microscopy.
3：List of Experimental Equipment and Materials:
A Ti:Sapphire regenerative amplifier, optical parametric amplifier, Fabry-Perot etalon, spectrograph, and emCCD camera were used for SFG experiments. The spectro-electrochemical cell was designed with PTFE parts, O-rings, and gold foil for electrical connection.
4：Experimental Procedures and Operational Workflow:
The cell was filled with electrolyte solution, and SFG spectra were acquired at different pH levels and applied voltages. The potential was controlled using a potentiostat.
5：Data Analysis Methods:
The SFG spectra were analyzed to determine the interfacial water structure, with normalization for the shape of the IR pulse using signals from gold-coated windows.
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