Labram raman spectrometer

The chemical structure and phase analysis of both samples were conducted by LabRAM Raman spectrometer (Horiba Instruments Inc., United States) HR evolution equipped with 785 nm (100mW) laser diode and backscattering configuration. The gratings were 600 g/mm with CCD detector (cooled at − 60 °C). The spectral resolution was 10 cm⁻¹, 25% laser power, and total acquisition of 5. The Raman spectra in the range of 1100–1800 cm⁻¹ were curve-fitted using Raman software.

The morphologies of the samples were studied by SEM (JEOL, JSM‐7500F) along with energy‐dispersive X‐ray spectroscopy and TEM (JEOL, JSM‐2100) using a TDY‐V5.2 image analysis system. Powder XRD was conducted in the 2θ range of 5°–70° with Cu Kα radiation (PANalytical B.V., X'Pert Pro diffractometer). XPS was performed on a Thermo electron spectrometer (ThermoFisher, Thermo) to investigate the bonding characteristics. Brunauer–Emmett–Teller specific surface areas and pore size distributions were determined using nitrogen adsorption–desorption isotherms (Micromeritics Instrument, ASAP 2460). FTIR spectroscopy was conducted with a diamond attenuated total reflectance (ATR) attachment (Thermo Fisher, Nicolet Magna 560). Raman spectra were obtained in the back‐scattering mode using an Arion laser (532 nm) on a LabRAM Raman spectrometer (Horiba Jobin Yvon). Solid‐state ³¹P NMR measurements were collected on an Agilent 600 m with a magnetic field intensity of 14.1 T. The MAS rotating frequency was 10 kHz, and the chemical shift refers to H₃PO₄. The product yield analysis of the oxidation of alcohols was performed using gas chromatography–mass spectrometry (GC‐MS; Agilent 7890B, HP‐5 column) and quantitative analyses using gas chromatography (GC; Agilent 8860, HP‐5 column).

The experimental setup used in this work to synthesize amorphous carbon nanospheres (Fig. 1) is shown in Figure S1. Argon was used as the carrier gas at a flow rate of 1 L/min. The carrier gas was flowed through the reactor for at least 30 min to purge the system prior to the addition of the precursor solution which was prepared by stoichiometrically mixing propiolic acid (95% from sigma-aldrich) with coressponding alkali hydroxides (99.99% from sigma-aldrich). The obtained black powders were washed and centrifuged with deionized water for at least 5 times to remove any salt formed during synthesis. The N₂ adsorption-desorption was carried out using Micromeritics ASAP 2020 physisorption analyzer to determine the density of porous carbon nanospehres studied in this work. TEM images were taken with a JEOL 2100 transmission electron microscope with an accelerating voltage of 200 kV. SEM images were taken using a Hitachi S4800 field-emission scanning electron microscope with an accelerating voltage of 10 kV. Powder X-ray diffraction patterns (PXRD) of the product were obtained with a Japan Rigaku DMax-γA rotation anode X-ray diffractometer equipped with graphite monochromatized Cu Kα radiation (λ = 1.54178 Å). Raman spectra were obtained directly from a thin film of carbon samples deposited on Si wafers on a Horiba Jobin-Yvon LabRAM Raman Spectrometer (excited with a 532 nm laser).