Chemistry below graphene: Decoupling epitaxial graphene from metals by potential-controlled electrochemical oxidation

Palacio, Irene; Otero‐Irurueta, Gonzalo; Alonso, C.; Martínez, José I.; López-Elvira, Elena; Muñoz-Ochando, Isabel; Salavagione, Horacio J.; López, María Francisca; Garcı́a-Hernández, M.; Méndez, Javier; Ellis, Gary; Martín‐Gago, José A.

doi:10.1016/j.carbon.2017.12.104

Cited by 31 publications

(36 citation statements)

References 75 publications

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“…[ 9,10 ] In all these cases, this interaction can be modulated or suppressed by controlled intercalation of metallic atoms at high temperatures, [ 11,12 ] or even at room temperature for alkaline elements. [ 13,14 ] The formation of an oxidized layer between substrate and graphene [ 15,16 ] can also decouple graphene from substrates.…”

Section: Introductionmentioning

confidence: 99%

Electronic Decoupling of Graphene from Copper Induced by Deposition of ZnO: A Complex Substrate/Graphene/Deposit/Environment Interaction

Morales

Urbanos

Campo

et al. 2020

Adv Materials Inter

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has been a turning point in the study and application of 2D materials. In this sense, the very high ballistic transport distances of the order of the micron and very large carrier mobility [2][3][4] combined with the absorption of 2.3% of visible light, [5] places graphene as an extraordinary candidate for new optoelectronic devices. On the other hand, graphene's impermeability to most gases [6] makes it also a promising candidate for ultrathin passivation coating. [7] However, this idealistic view contrasts with the reduced number of real applications to industry and/or produced mass electronic devices. Without doubt, this frustrating fact is related to the difficulty to grow large areas of non-defective graphene, but also with the complexity of the interaction of graphene with other materials (substrates, multilayer systems) and/or media (gas, liquids) in contact with it, which leads to changes of the graphene properties.Focusing on this last point, the substrate plays a very important role in the electronic properties of graphene due to the strength of the bonding between both. As Weatherup et al. summarized, [7] depending on the position of the d valence band states with respect to the Fermi level, [8] two different interactions are reported for metallic substrates. In the case of Ni, Co, Fe, or Pd, the strong hybridization between π graphene states and metal d states leads to the destruction of the linear dispersion of graphene at the K point. For weak interactions, such as Cu, Au, Ag, and Pt, this linear dispersion is preserved but charge transfer between metal and graphene normally shifts the Fermi level position, leading to doping of graphene. Moreover, for SiC (0001) a covalent bonding between the substrate and the first carbon layer also prevents good electrical properties of graphene. [9,10] In all these cases, this interaction can be modulated or suppressed by controlled intercalation of metallic atoms at high temperatures, [11,12] or even at room temperature for alkaline elements. [13,14] The formation of an oxidized layer between substrate and graphene [15,16] can also decouple graphene from substrates.Nevertheless, the last description offers again a simplified view of the problem. The majority of the experimental and This study presents experimental data of the interactions and reactions that occur during the early stages of the growth of ZnO on graphene supported on polycrystalline copper and the subsequent changes on the electronic properties of the graphene. The combination of substrate, graphene, and intercalated species (such as oxygen and water molecules) between graphene and copper due to air exposure, together to the evaporation of metallic zinc under oxygen atmosphere, induces the electronic decoupling of the graphene from copper by the formation of a nanometric layer of copper oxide. In particular, the final stage consists in the formation of a complex interface formed by ZnO/ZnO 1−x /Zn/G/Cu 2 O/Cu. The role of each actor is discussed in terms of a galvanic corrosion reaction of the met...

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Section: Introductionmentioning

confidence: 99%

Electronic Decoupling of Graphene from Copper Induced by Deposition of ZnO: A Complex Substrate/Graphene/Deposit/Environment Interaction

Morales

Urbanos

Campo

et al. 2020

Adv Materials Inter

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“…Among the family of graphene materials, graphene oxide (GO) as well as reduced graphene oxide (rGO) seem to be better positioned than pristine graphene for industrial applications. This is because of some of their chemical methods are well established for synthesizing bulk quantities of GO [3][4][5] and rGO [5][6][7], while it is much more complex to obtain pristine graphene [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, these methods have several drawbacks that limit the potential applications of the obtained material. The GO flakes produced by these methods usually have uneven shapes, with a thickness of a few layers and a maximum lateral size of few microns [5][6][7][8][9][10][11][12]. The preparation of thin films or paper-like GO by stacking GO flakes [13][14][15][16] is a good approach for partially overtaking the above-mentioned limitations.…”

Section: Introductionmentioning

confidence: 99%

Chemical Changes of Graphene Oxide Thin Films Induced by Thermal Treatment under Vacuum Conditions

et al. 2020

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Reduction of graphene oxide is one of the most promising strategies for obtaining bulk quantities of graphene-like materials. In this study, graphene oxide was deposited on SiO2 and reduced by annealing at 500 K under vacuum conditions (5 × 10−1 Pa). Here, graphene oxide films as well as their chemical changes upon heating were characterized in depth by X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron and atomic force microscopies. From the chemical point of view, the as prepared graphene oxide films presented a large quantity of oxidized functional groups that were reduced to a large extent upon heating. Moreover, residual oxidized sulfur species that originated during the synthesis of graphene oxide (GO) were almost completely removed by heating while nitrogen traces were integrated into the carbon framework. On the other hand, regarding structural considerations, reduced graphene oxide films showed more homogeneity and lower roughness than graphene oxide films.

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“…A second peak located at 284.81 eV was required for optimal fitting of the experimental data and a Voigt curve was used in this case. This small peak is present from the start of the annealing process and it is ascribed to sp 3 carbon [ 15 , 46 ], which mainly comes from the graphene grain boundaries. The contribution of sp 3 carbon, as already observed in previous works, can be low and even almost negligible [ 25 ].…”

Section: Resultsmentioning

confidence: 99%

Oxygen intercalation in PVD graphene grown on copper substrates: A decoupling approach

Azpeitia

Palacio

Martínez

et al. 2020

Applied Surface Science

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We investigate the intercalation process of oxygen in-between a PVD-grown graphene layer and different copper substrates as a methodology for reducing the substrate-layer interaction. This growth method leads to an extended defect-free graphene layer that strongly couples with the substrate. We have found, by means of X-ray photoelectron spectroscopy, that after oxygen exposure at different temperatures, ranging from 280 °C to 550 °C, oxygen intercalates at the interface of graphene grown on Cu foil at an optimal temperature of 500 °C. The low energy electron diffraction technique confirms the adsorption of an atomic oxygen adlayer on top of the Cu surface and below graphene after oxygen exposure at elevated temperature, but no oxidation of the substrate is induced. The emergence of the 2D Raman peak, quenched by the large interaction with the substrate, reveals that the intercalation process induces a structural undoing. As suggested by atomic force microscopy, the oxygen intercalation does not change significantly the surface morphology. Moreover, theoretical simulations provide further insights into the electronic and structural undoing process. This protocol opens the door to an efficient methodology to weaken the graphene-substrate interaction for a more efficient transfer to arbitrary surfaces.

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Chemistry below graphene: Decoupling epitaxial graphene from metals by potential-controlled electrochemical oxidation

Cited by 31 publications

References 75 publications

Electronic Decoupling of Graphene from Copper Induced by Deposition of ZnO: A Complex Substrate/Graphene/Deposit/Environment Interaction

Electronic Decoupling of Graphene from Copper Induced by Deposition of ZnO: A Complex Substrate/Graphene/Deposit/Environment Interaction

Chemical Changes of Graphene Oxide Thin Films Induced by Thermal Treatment under Vacuum Conditions

Oxygen intercalation in PVD graphene grown on copper substrates: A decoupling approach

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