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Reduced graphene oxide-catalyzed oxidative coupling reaction of 4-methoxyphenol in aerobic aqueous solution
- Source :
- Carbon. 121:418-425
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- Three reduced graphene oxide (rGO) with different defect contents were prepared at 250, 600 and 1000 °C, respectively, using thermal reduction method, and their effects on the oxidative coupling processes of 4-methoxyphenol (MOP) in aqueous solution were investigated. In the presence of rGOs, the oxidation of MOP was dramatically accelerated. At the same surface area dose, the catalytic efficiencies of three rGOs followed an ascending order of rGO 250 ≤ rGO 600 1000 . Using liquid chromatography-mass spectrometry and molecular modeling computation, we identified the coupling products (dimer, trimer, and tetramer), and revealed that ortho C O and ortho-ortho C C coupling between two MOP radicals were the main reaction pathways. Dissolved oxygen and structural defects of rGOs played important roles in the oxidation of MOP. It is proposed that dissolved oxygen reacted with the defect sites of rGO to produce surface-bound superoxide species, which captured H atom from the phenolic hydroxyl group of MOP to generate MOP radical and H 2 O 2 . A portion of H 2 O 2 can be catalyzed further by rGO to hydroxyl radical, which continued to react with MOP to produce MOP radical and H 2 O.
- Subjects :
- Aqueous solution
Chemistry
Radical
Dimer
Oxide
Trimer
02 engineering and technology
General Chemistry
010501 environmental sciences
021001 nanoscience & nanotechnology
Photochemistry
01 natural sciences
Catalysis
chemistry.chemical_compound
General Materials Science
Oxidative coupling of methane
Hydroxyl radical
0210 nano-technology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 00086223
- Volume :
- 121
- Database :
- OpenAIRE
- Journal :
- Carbon
- Accession number :
- edsair.doi...........c1851d11d84a27e9b0795b357a5fe709