Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies
Reduced graphene oxide (rGO) was prepared by chemical reduction of graphene oxide (GO) (with a modified Hummers method) in aqueous solutions of hydrazine (N<sub>2</sub>H<sub>4</sub>), formaldehyde (CH<sub>2</sub>O), formic acid (HCO<sub>2</sub>H) accom...
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| author | Beata Lesiak Grzegorz Trykowski József Tóth Stanisław Biniak László Kövér Neha Rangam Artur Małolepszy Leszek Stobiński |
| author_facet | Beata Lesiak Grzegorz Trykowski József Tóth Stanisław Biniak László Kövér Neha Rangam Artur Małolepszy Leszek Stobiński |
| author_sort | Beata Lesiak |
| collection | DOAJ |
| description | Reduced graphene oxide (rGO) was prepared by chemical reduction of graphene oxide (GO) (with a modified Hummers method) in aqueous solutions of hydrazine (N<sub>2</sub>H<sub>4</sub>), formaldehyde (CH<sub>2</sub>O), formic acid (HCO<sub>2</sub>H) accompanied by a microwave treatment at 250 °C (MWT) by a high pressure microwave reactor (HPMWR) at 55 bar. The substrates and received products were investigated by TEM, XRD, Raman and IR spectroscopies, XPS, XAES and REELS. MWT assisted reduction using different agents resulted in rGOs of a large number of vacancy defects, smaller than at GO surface C sp<sup>3</sup> defects, oxygen groups and interstitial water, interlayer distance and diameter of stacking nanostructures (flakes). The average number of flake layers obtained from XRD and REELS was consistent, being the smallest for CH<sub>2</sub>O and then increasing for HCO<sub>2</sub>H and N<sub>2</sub>H<sub>4</sub>. The number of layers in rGOs increases with decreasing content of vacancy, C sp<sup>3</sup> defects, oxygen groups, water and flake diameter. MWT conditions facilitate formation of vacancies and additional hydroxyl, carbonyl and carboxyl groups at these vacancies, provide no remarkable modification of flake diameter, what results in more competitive penetration of reducing agent between the interstitial sites than via vacancies. MWT reduction of GO using a weak reducing agent (CH<sub>2</sub>O) provided rGO of 8 layers thickness. |
| first_indexed | 2024-03-10T06:56:27Z |
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| id | doaj.art-e99acc6169ee49528ffefec217faa876 |
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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T06:56:27Z |
| publishDate | 2021-09-01 |
| publisher | MDPI AG |
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| series | Materials |
| spelling | doaj.art-e99acc6169ee49528ffefec217faa8762023-11-22T16:26:14ZengMDPI AGMaterials1996-19442021-09-011419572810.3390/ma14195728Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic StudiesBeata Lesiak0Grzegorz Trykowski1József Tóth2Stanisław Biniak3László Kövér4Neha Rangam5Artur Małolepszy6Leszek Stobiński7Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, PolandFaculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, PolandInstitute for Nuclear Research, P.O. Box 51, H-4001 Debrecen, HungaryFaculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, PolandInstitute for Nuclear Research, P.O. Box 51, H-4001 Debrecen, HungaryInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, PolandFaculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, PolandFaculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, PolandReduced graphene oxide (rGO) was prepared by chemical reduction of graphene oxide (GO) (with a modified Hummers method) in aqueous solutions of hydrazine (N<sub>2</sub>H<sub>4</sub>), formaldehyde (CH<sub>2</sub>O), formic acid (HCO<sub>2</sub>H) accompanied by a microwave treatment at 250 °C (MWT) by a high pressure microwave reactor (HPMWR) at 55 bar. The substrates and received products were investigated by TEM, XRD, Raman and IR spectroscopies, XPS, XAES and REELS. MWT assisted reduction using different agents resulted in rGOs of a large number of vacancy defects, smaller than at GO surface C sp<sup>3</sup> defects, oxygen groups and interstitial water, interlayer distance and diameter of stacking nanostructures (flakes). The average number of flake layers obtained from XRD and REELS was consistent, being the smallest for CH<sub>2</sub>O and then increasing for HCO<sub>2</sub>H and N<sub>2</sub>H<sub>4</sub>. The number of layers in rGOs increases with decreasing content of vacancy, C sp<sup>3</sup> defects, oxygen groups, water and flake diameter. MWT conditions facilitate formation of vacancies and additional hydroxyl, carbonyl and carboxyl groups at these vacancies, provide no remarkable modification of flake diameter, what results in more competitive penetration of reducing agent between the interstitial sites than via vacancies. MWT reduction of GO using a weak reducing agent (CH<sub>2</sub>O) provided rGO of 8 layers thickness.https://www.mdpi.com/1996-1944/14/19/5728graphene oxide (GO)reduced graphene oxide (rGO)structuralchemical properties |
| spellingShingle | Beata Lesiak Grzegorz Trykowski József Tóth Stanisław Biniak László Kövér Neha Rangam Artur Małolepszy Leszek Stobiński Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies Materials graphene oxide (GO) reduced graphene oxide (rGO) structural chemical properties |
| title | Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies |
| title_full | Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies |
| title_fullStr | Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies |
| title_full_unstemmed | Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies |
| title_short | Effect of Microwave Treatment in a High Pressure Microwave Reactor on Graphene Oxide Reduction Process—TEM, XRD, Raman, IR and Surface Electron Spectroscopic Studies |
| title_sort | effect of microwave treatment in a high pressure microwave reactor on graphene oxide reduction process tem xrd raman ir and surface electron spectroscopic studies |
| topic | graphene oxide (GO) reduced graphene oxide (rGO) structural chemical properties |
| url | https://www.mdpi.com/1996-1944/14/19/5728 |
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