Micro raman spectroscopy system

The surface morphology of the various films measured over 10 μm × 10 μm and 1 μm × 1 μm regions was measured using scanning atomic force microscopy (AFM, Veeco Dimension V) in tapping mode for the H-terminated NDs. The chemical composition and bonding states of the films were characterized using Fourier transfer infrared spectrometry (FTIR, Perkin Elmer Spectrum One) in transmission mode and X-ray photoelectron spectroscopy (XPS, Thermo Scientific) with the Al K α line as the exciting source. A micro Raman spectroscopy system (Renishaw Invia) operating at 514.5 nm was used to study the film microstructure, where the laser output power used was 1 mW. Impedance spectroscopy was applied in the range of 0.1 Hz to 10 MHz in a vacuum at elevated temperature from room temperature to 500 C using an Autolab electrochemical system. Hall Effect measurements (1T electromagnet, Lakeshore Cryogenics System) were performed to determine graphene carrier mobilities using the “van der Pauw” method, where by four Ohmic metal contacts (10 nm Ti-300 nm Au) were placed on the topside of the graphene layers at room temperature.

All the SEM images were collected on a tungsten thermionic emission SEM system (the Tescan VEGA3). XRD spectra were obtained from the XRD system (Rigaku SmartLab) equipped with a 9 kW rotating anode X-ray source (λ ~ 1.54 Å) coupling with a high-quality semiconductor detector that supports 0D, 1D, or 2D x-ray diffraction measurement. Raman spectra were recorded from Renishaw Micro-Raman Spectroscopy system fully integrated with a confocal microscope spectrometer and a 785 nm laser source. Mechanical tests were conducted on an advanced rheometric expansion system at the Hong Kong University of Science and Technology. All the electrochemical tests were processed on an electrochemical workstation (VersaSTAT3). The measurements of OECT were conducted on a probe station (Micromanipulator) with Keithley 4200A-SCS parameter analyzer. The test of viscosity was conducted by the viscometer (NDJ-5S/9 S/8 S). The probe of viscometer inserted into PAni gels after soaking in solvents, and the viscosity was measured at an increasing shear speed from 10 to 60 Rev.