In order to bind hydrogen to the graphene surface we used a cold hydrogen dc plasma at a low-pressure (~0.1 mbar) H2/Ar (1:10) mixture. The plasma was ignited between Al electrodes. The level of hydrogenation was estimated by measuring the D to G peak intensity for hydrogenated samples registered by using a Witec alpha 300R Raman spectrometer at a 514 nm excitation wavelength. A typical distance between hydrogen sites LD was calculated as , where λ is the wavelength measured in nanometers, I(G) and I(D) are the intensities for the G and D Raman peaks of hydrogenated graphene7 (link). This yields LD≈10 nm after the 30 min hydrogenation. We assume that the size of possible hydrogen clusters is smaller than the inter-cluster distance (~5 nm), which gives us an estimate of 17% hydrogenation after 30 min. It is worth noting that graphene hydrogenation is a reversible process which can be reverted by a soft anneal7 (link).
Alpha 300 r raman spectrometer
Manufactured by WITec
Sourced in Germany
The Alpha 300 R Raman spectrometer is a versatile and high-performance laboratory instrument designed for Raman spectroscopy analysis. It features a modular design, allowing for customization to meet specific research needs. The system is equipped with advanced optical components and a sensitive detector to provide accurate and reliable Raman spectra measurements.
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7 protocols using alpha 300 r raman spectrometer
1
Hydrogenation of Graphene via Plasma
2
In situ Raman Spectroscopy of CO2 Electrolysis
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In situ Raman spectra were recorded on a WITec Alpha 300R Raman spectrometer with a 633-nm laser as the excitation light source. The experiments were performed in a self-made flow cell as shown inSupplementary Fig. S33 . CO2 gas was introduced to the back of the GDL at a flow rate of 50 sccm controlled by a rotameter. The CO2 electrolysis was controlled by chronopotentiometry. The current was increased gradually while in situ Raman spectra were recorded.
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In situ Raman spectra were recorded on a WITec Alpha 300R Raman spectrometer with a 633-nm laser as the excitation light source. The experiments were performed in a self-made flow cell as shown in
3
Characterization of PEGylated Graphene Oxides
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The small (s-GOs) and large (l-GOs) lateral-sized GOs were obtained using ultrasound-assisted exfoliation. The PEGylated GOs were synthesized according to our previous method [4 (link)]. Briefly, s-GOs and l-GOs were sonicated for 10 h and 10 min in an ice-water bath, respectively. The polyethylene glycol-modified GOs were prepared via EDC/NHS chemistry at room temperature. Then, the PEGylated s-GOs and l-GOs were purified by centrifugation, followed by dialysis for 12 h to remove free impurities.
Atomic force microscopy (AFM, AFM5500, Bruker, Billerica, UK) was used to characterize the thickness, size, and morphology of GOs. The Raman spectra of GOs were measured using a WITec Alpha 300 R Raman spectrometer (WITec, Ulm, Germany) with a 532 nm laser. The hydrodynamic diameters and zeta potential of GOs in deionized water or cell culture medium (DMEM) were measured using Zetasizer Nano ZS90 (MALVERN, Malvern, UK).
Atomic force microscopy (AFM, AFM5500, Bruker, Billerica, UK) was used to characterize the thickness, size, and morphology of GOs. The Raman spectra of GOs were measured using a WITec Alpha 300 R Raman spectrometer (WITec, Ulm, Germany) with a 532 nm laser. The hydrodynamic diameters and zeta potential of GOs in deionized water or cell culture medium (DMEM) were measured using Zetasizer Nano ZS90 (MALVERN, Malvern, UK).
4
Raman Spectroscopy of Doped Crystals
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Raman spectra of crystals were measured using a WITEC Alpha 300 R Raman spectrometer equipped with a 532 nm laser in vacuum conditions (below 10−6 Torr). When the electric current fully saturates, the doping was stopped by turning off the source heater. For the Raman measurements, the doping system was detached from the vacuum pump, and loaded into an argon-filled glove box. Then, the doped single crystals were transferred to another chamber with a glass viewport through which laser light and Raman signals can be transmitted while retaining the sample in an inert environment (Fig. S13 ). The power of the laser was set to 750 μW in order to prevent thermal damage during the measurements, and all Raman measurements were conducted under argon environment.
5
In Situ Raman Characterization of Water Droplet
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Figure 2a shows the setup for in situ Raman test (WITec alpha300 R Raman spectrometer) employing quartz glass as the substrate to reduce the undesired background signal. Before characterization, the system was calibrated with Si peak at 520 cm−1. A single water droplet was placed in the middle of the quartz glass, which was protected by a convection blocker. A copper wire electrode was supported by two spacers to keep a 1‐mm distance from the water surface. During the test, laser intensity (<1 mW, 532 nm) and other parameters were kept unchanged with only the external voltage on the electrode varying. Both temperature and humidity were well controlled in the characterization room.
6
Characterization of Graphene Oxide Nanostructures
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The thickness, size and morphology of the s-GOs and l-GOs were characterized by atomic force microscopy (AFM, AFM5500, Bruker, UK) and transmission electron microscopy (TEM, JEOL, JEM-2100F). The content of functional groups on GO was analyzed by means of synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) at 4B9B beamline of Beijing Synchrotron Radiation Facility (BSRF), China. Raman spectra were measured using a WITec Alpha 300 R Raman spectrometer (WITec, Germany) with a 532 nm laser. The concentration of Yb on GOs was determined by inductively coupled plasma mass spectrometry (ICP-MS, NexION 300D, PerkinElmer, Inc., USA).
7
Bacterial Raman Spectroscopy for Identification
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Fixed bacterial samples were centrifuged by using a Cytospin centrifuge (Hettich, Germany) onto CaF 2 slides (Crystal, Germany) coated with 0.2% gelatin in order to obtain a uniform bacterial layer and to ensure good attachment for bulk measurement. The samples were characterized with an alpha300R Raman spectrometer (WITec, Germany) in PBS buffer using a 60Â water immersion objective (NA 1.0, Nikon) and a 532-nm Nd: YAG laser at 15 mW. A 100-μm multimode fiber was used to collect the light scattered from the bacteria. Excitation wavelength of 532 nm was chosen, as it is available in many commercial Raman devices and thus could be used for potential later translation. In addition, extensive databases for the identification of bacteria have been recorded previously with this wavelength. [39, 40] Spectra were recorded of each strain on different spatial positions of the sample using an integration time of 5 s/spectrum and one accumulation. One spectrum was recorded per position to give a total of 32-38 spectra per strain from the 32-38 different positions. For 47 strains, this results in a total number of 1570 Raman spectra. After preprocessing, 1529 spectra were included in the final analysis.
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