Ion irradiation reduces oxidized graphene but causes morphological and structural changes in individual sheets. Graphene oxide (GO) films were irradiated under vacuum with ion beams having different atomic numbers and energies in the range (2-16) MeV. The structural and morphological changes undergone by the individual sheets of reduced graphene oxide (rGO) were analyzed by transmission electron microscopy and Raman spectroscopy. In particular, the electron diffraction highlights the deformations of the sheets through the deformation of the diffraction spots. A quantitative structural evaluation of such features was carried out using a new method based on the analysis of the radial and azimuth profiles extracted from the electron diffraction pattern. The spots deformation involves both the direction normal to the reciprocal lattice vectors and the parallel one. The former deformation is related to the non-planarity of the surface, the latter to the rearrangement of the deformed lattice. Experimental evidence indicates that there are many different orientations present within the electron beam with a diameter of less than one micron and that the surface normal of the sheet must vary in all directions. This is the result of a microscopic roughness inside the sheets. The progressive deformation of the spots depends on the absorbed ion dose. The morphological analysis, carried out at high resolution on rGO sheets, confirms structural results: the rGO sheets take on a static not flat but rippled configuration. Accentuated ripples are dose dependent.

From GO to rGO: An analysis of the progressive rippling induced by energetic ion irradiation

L. Torrisi
Secondo
;
L. Silipigni;
2022-01-01

Abstract

Ion irradiation reduces oxidized graphene but causes morphological and structural changes in individual sheets. Graphene oxide (GO) films were irradiated under vacuum with ion beams having different atomic numbers and energies in the range (2-16) MeV. The structural and morphological changes undergone by the individual sheets of reduced graphene oxide (rGO) were analyzed by transmission electron microscopy and Raman spectroscopy. In particular, the electron diffraction highlights the deformations of the sheets through the deformation of the diffraction spots. A quantitative structural evaluation of such features was carried out using a new method based on the analysis of the radial and azimuth profiles extracted from the electron diffraction pattern. The spots deformation involves both the direction normal to the reciprocal lattice vectors and the parallel one. The former deformation is related to the non-planarity of the surface, the latter to the rearrangement of the deformed lattice. Experimental evidence indicates that there are many different orientations present within the electron beam with a diameter of less than one micron and that the surface normal of the sheet must vary in all directions. This is the result of a microscopic roughness inside the sheets. The progressive deformation of the spots depends on the absorbed ion dose. The morphological analysis, carried out at high resolution on rGO sheets, confirms structural results: the rGO sheets take on a static not flat but rippled configuration. Accentuated ripples are dose dependent.
2022
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3231105
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