Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

Abstract

SummaryCarbonization of tomatoes at 240 °C using 30% (w/v) NaOH as catalyst produced carbon onions (C-onions), while solely carbon dots (C-dots) were obtained at the same temperature in the absence of the catalyst. Other natural materials, such as carrots and tree leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV–vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanomaterials. Preliminary tests demonstrate a capability of the versatile materials for chemical sensing of metal ions. The high content of lycopene in tomatoes may explain the formation of C-onions in alkaline media and a possible formation mechanism for such structures was outlined.

Carbon Nano‐Onion and Zinc Oxide Composites as an Electron Transport Layer in Inverted Organic Solar Cells

“…The FTIR spectra of the CNOs, Zn(OH) 2 , ZnO and their composites are shown in Figure . The CNO infrared spectrum shows a peak at 1599 cm −1 corresponding to aromatic C=C stretching vibration, which confirmed the presence of sp 2 ‐hybridized carbon atoms in the CNs . Two bands occurring at 1247 and 1741 cm −1 can be assigned to C−O−C and C=O stretching vibrations, respectively .…”

“…spectrum shows a peak at 1599 cm À 1 corresponding to aromatic C=C stretching vibration, which confirmed the presence of sp 2hybridized carbon atoms in the CNs. [59] Two bands occurring at 1247 and 1741 cm À 1 can be assigned to CÀ OÀ C and C=O stretching vibrations, respectively. [60] The presence of oxygen in the carbon sample is probably caused by the annealing of the CNOs after their formation at 400°C in air.…”

In situ synthesis of noble metal nanoparticles on onion-like carbon with enhanced electrochemical and supercapacitor performance

“…However the O-H vibration at 1627 cm À1 which should decrease aer the reduction of chloroplatinic acid exhibits no obvious difference. 23,24 The high-resolution C 1s XPS spectra of OLC and Pt-OLC in Fig. 3 show us more detailed information.…”

Hydrothermal Synthesis of Carbon Nano‐Onions from Citric Acid

“…NaOH as catalyst produced CNOs in the products. [8] On the other hand, the graphene quantum dots (GQD) and the graphene oxides (GO) could be synthesized by the direct carbonization of citric acid (CA) in a beaker at 200°C as the heating time extended from 30 minutes to 2 hours. [9] Here we show a hydrothermal synthesis of CNOs from precursors of CA at 180°C, which was operated at more gentle conditions and lower temperature compared with the previous methods.…”

“…[15] The Fourier transform infrared (FT-IR) spectrum of the CNOs in Figure 2 ( 1590, 1400 and 1120 cm À 1 . [8] The oxygen atomic fraction of the CNOs was measured by the energy dispersive X-ray spectroscopy (EDS) to be 10.84% (Table S1), which may be resulted by the incomplete dehydration of CA molecules and the hydrothermal environment during the CNO synthesis. In order to reveal the formation process of CNOs during the hydrothermal carbonization of CA, we carefully observed the carbon morphologies of the products from the hydrothermal carbonization of CA by TEM.…”