Graphene Oxide Foils Research Articles

Hybrid graphene-based material promising target in laser matter interaction

Graphene oxide foils implanted with copper ions at low energy and high dose, have been proposed as hybrid graphene-based materials suitable to be laser irradiated in vacuum to produce hot plasmas. The special lattice structure of the graphene oxide foil can improve the propagation of the laser accelerated electrons inside the foil and to enhance the electron density emerging from the rear foil surface. In such conditions the electric field developed in the non-equilibrium plasma increases and consequently in the forward ion acceleration. The foils have been optimized in thickness and they were irradiated with optimized laser parameters in order to produce high energy and quasi-monoenergetic proton beams by the femtosecond laser at the Institute of Plasma Physics and Laser Microfusion in Warsaw, Poland. Gaf chromic film and silicon carbide detectors were used to monitor the plasma properties and to measure the velocity of the emitted protons and carbon ions from plasma.

Reduced graphene oxide foils for ion stripping applications

ABSTRACTReduced graphene oxide (rGO) films can be employed as ion strippers in an accelerator. They show some advantages with respect to the graphite foils, due to their high thermal and electrical conductivity, low density, high mechanical resistance and high stability. Thin graphene oxide (GO) films with a sub-micron thickness have been synthesized and transformed into reduced GO (rGO) by ion beam irradiations. Physical characterizations of the pristine and ion irradiated GO films have been performed. Measurements of stripping efficiency have been carried out by using helium, lithium, carbon and oxygen ion beams. The rGO stripper films demonstrate a significantly high charge production, comparable to that of the graphite films but with the advantage of a longer lifetime.

Evolution of Silicon-Nickel Nanosheets on (111) Silicon Substrates to Realize Reduced Graphene Oxide-Silicide Heterostructures

We report the evolution of ultra-thin silicon-nickel nanosheets on (111) silicon substrates using a hydrogen plasma processing. A novel stress-induced lateral-diffusion method has been employed to realize thin layers of Si-Ni flakes containing nickel quantum dots. The presence of carbon during the growth is critical to form carbon-silicon nanostructures and subsequently induce strain on (111) planes of silicon substrate. The lateral diffusion of Ni between (111) planes is enhanced at the presence of strain to realize silicon-nickel sheets. These sheets have been examined using TEM, AFM, SEM, EDS, XRD, Raman spectroscopy and photo-luminescence analyses. In addition, we have used graphene-oxide (GO) foils to place on the surface of these layers. By a hydrogen plasma treatment, the GO foil is reduced into rGO on silicon-nickel sheets. Finally, an rGO/Si-Ni nanosheet hetero-structures on (111) silicon substrates is formed. To have electrical contacts to the top rGO layer, we have used an indium tin oxide (ITO)-coated glass to complete the device. A preliminary light emission device has been realized and tested.

Effects of the Laser Irradiation on Graphene Oxide Foils in Vacuum and Air

A Nd:YAG laser operating at 1064 nm was used to irradiate, at different intensities, graphene oxide foils placed in vacuum and in air. The laser irradiated GO foils were analysed successively by using different techniques such as 2.0 MeV alpha particle Rutherford backscattering spectrometry, X-ray photoemission spectroscopy and SEM-EDX. In particular, in vacuum irradiated graphene oxide samples the oxygen reduction has been observed with increment of the carbon content. In air irradiated GO samples an increase in oxygen has instead been highlighted. Furthermore thermal and chemical effects are induced by the photon irradiation. Results will be presented and discussed.

Effects of the ion bombardment on the structure and composition of GO and rGO foils

In recent years graphene and its derivatives, have attracted scientific interest due to their unique properties. This study is to explore the quality of synthesized graphene oxide and reduced graphene oxide foils under the irradiation of protons and helium ions of the same energy and current. Fully characterizations by Raman spectroscopy, Rutherford backscattering spectrometry and Elastic recoil detection analysis and the relative results are presented. The effects of parameters, such as type of ions, their current and irradiation time, are studied. The quality of large-scale fabrication of graphene oxide and reduced graphene oxide (rGO) is important for industrial and research applications of these materials. An overview on the changes in the optical property and electron conductivity of graphene oxide and reduced graphene oxide under irradiation by protons, helium and carbon ions are also summarized.

Characterization of graphene oxide film by implantation of low energy copper ions

Graphene oxide (GO) is an electrical insulator as most of the carbon atoms in this material are sp3-hybridized. Its physical, optical and chemical properties depend on the type and degree of reduction process. Presently, copper ion irradiation of GO foil has been performed at Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf to investigate the behavior of a set of GO foils under this irradiation at low energy and different fluences up to 5 × 1016 ions/cm2. The compositional and optical properties of graphene oxide have been studied as a function of the fluences of implanted copper ions in the wavelength range 400–1000 nm. The results of ellipsometry microscopy, helium Rutherford backscattering spectroscopy, elastic recoil detection analysis, Raman spectroscopy and SEM-EDX measurements will be presented and discussed.

Structural and compositional modification of graphene oxide by means of medium and heavy ion implantation

Graphene and its allotropes belong to the new generation of materials. Due to their extraordinary electrical, mechanical and other properties, their application possibilities are vast. In this work, a study on interactions of graphene oxide (GO) layers using Au and Ga ions with energy of 40 keV was realized. Very shallow layers of GO are modified as low energy ions are depositing energy mostly in the upper layer due to the low projected ion ranges at most of 50 nm. The ion irradiation fluences of 5.0 × 1014 cm−2, 5.0 × 1015 cm−2 and 5.0 × 1016 cm−2 were used. Upon irradiation, the modified GO foils were characterised using nuclear analytical methods – Rutherford Backscattering Spectrometry (RBS), Elastic Recoil Detection Analysis (ERDA) and various conventional analytical methods such as Raman spectroscopy, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS), and 2-point conductivity measurements. Oxygen species removal was evidenced as the increasing function of the ion implantation fluence and oxygen depth profiles exhibited complex behaviour connected to implanted ion specie. The deep oxygen depletion in the broad surface layer accompanied by Ga diffusion into the depth was observed in Ga irradiated GO compared to Au irradiated samples which exhibited a narrow oxygen depleted layer at GO surface. XPS evidenced strong increase of CC bonds compared to CO bonds on the irradiated GO surface with increasing ion fluence, which was comparable for both ion species. Raman spectroscopy shows the modification of main phonon modes identified in GO. The D peak slight decrease and broadening was observed for GO irradiated with ion fluence above 5 × 1015 cm−2 and mainly for Au ion irradiation. FTIR analysis proved the oxygen containing functional group release with the increased ion fluence, mainly CO group release after Au ion irradiation was observed. Simultaneously HO stretching absorption peak is in FTIR spectrum reduced more significantly for Ga irradiated GO which is in accordance with RBS elemental analysis exhibiting the more pronounced hydrogen depletion. Electrical conductivity measurement shows the linear I-V characteristics for the GO irradiated using both ion species and all ion fluences; the surface layer exhibited conductive behaviour comparing to pristine GO non-linear I-V characteristics.

Graphene Oxide Foils as an Osteoinductive Stem Cell Substrate.

The hydrophilic graphene derivative, graphene oxide (GO), is used to synthesize free-standing GO foils characterized by cross-linked GO sheets with enhanced mechanical properties and no tendency to release GO flakes in aqueous solution. These GO foils do not evidence cytotoxic effects toward dental pulp stem cells (DPSC). Rather, DPSC viability is significantly increased for cells grown on GO foil and SEM analyses evidence the synthesis of a consistent extracellular matrix by DPSCs with respect to cells grown on polystyrene. Gene expression of osteogenic markers and alkaline phosphatase (ALP) activity tests demonstrate DPSC differentiation toward the osteoblastic lineage. Indeed RUNX2, a key transcriptor factor associated with osteogenic differentiation, as well as SP7, responsible for triggering bone matrix mineralization, are significantly augmented after 7 and 14 days of culture on GO foil with respect to the control, respectively, underlying the capability of GO foil to promote a potential faster and better DPSC differentiation with respect to cells grown on polystyrene. This increase of rate differentiation is confirmed by SEM analyses of DPSCs evidencing a consistent extracellular matrix synthesis at the earliest time of culture (i.e., 3 and 14 days).

Localized deoxygenation of graphene oxide foil by ion microbeam writing

An efficient mask-less production of patterns in insulating foils of graphene-oxide was carried out under impact of 5 MeV alpha particle beams delivered by the Ion Micro Beam system at the Tandetron Laboratory of the Nuclear Physics Institute in Rez (Czech Republic). Graphene-oxide (GO) matrix has been exposed to controlled fluences with the aim of inducing deoxygenation and enhancement of the electrical conductivity in selected areas of the exposed samples. The reported designed patterns and their sharp edge profiles demonstrate the feasibility of the process.The compositional changes in the exposed areas of the GO were investigated by Rutherford backscattering spectrometry, elastic recoil detection analysis, scanning electron microscopy, and correlated with the electrical properties measured by a standard 2-point probe technique.

Effects of the laser irradiation on graphene oxide foils in vacuum and air -=SUP=-*-=/SUP=-

AbstractA Nd:YAG laser operating at 1064 nm was used to irradiate, at different intensities, graphene oxide foils placed in vacuum and in air. The laser irradiated GO foils were analysed successively by using different techniques such as 2.0 MeV alpha particle Rutherford backscattering spectrometry, X-ray photoemission spectroscopy and SEM-EDX. In particular, in vacuum irradiated graphene oxide samples the oxygen reduction has been observed with increment of the carbon content. In air irradiated GO samples an increase in oxygen has instead been highlighted. Furthermore thermal and chemical effects are induced by the photon irradiation. Results will be presented and discussed.

Reprint of “Graphene oxide layers modified by irradiation with 1.2 MeV He+ ions”

The irradiation with 1.2 MeV He+ ions to various fluences was successfully used for modification of graphene oxide (GO). The elemental composition of the GO foils before and after He+ ion irradiation was investigated using Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis. The chemical composition and structural changes of the GO foil surface were characterized by X-Ray Photoelectron and Raman spectroscopy and changes in the electrical properties was studied by standard two point method. The obtained data indicate the removal of oxygen functionalities and growth of the graphene domains on the GO surface that leads to the improvement of surface conductivity which is a growing function of the ion fluence.

Tailoring the oxygen content of graphene oxide by IR laser irradiation

Graphene oxide (GO) foils, synthesized with the Hummers’ method, were IR laser treated in air and under vacuum at some laser fluences (300 and 600 mJ/cm2 in air and 200 mJ/cm2 under vacuum). Depending on the laser fluence and the used environment, it was possible to control the oxidation or reduction degree of GO foils. The evolution of the structural and compositional characteristics of the as-prepared GO films was examined through different physical characterization techniques. In particular, scanning electron microscopy (SEM), surface profilometry, energy-dispersive X-ray spectroscopy (EDX), Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) were used. A preliminary Raman analysis was also carried out on some GO foils. The results suggest the gradual restoration of sp2 clusters within the sp3 matrix under vacuum or in air at high laser fluences. In these conditions, the partial reestablishment of planarity and an increase in the D/G intensity ratio are also observed. In air, at low laser fluences, the IR laser irradiation causes GO films oxidation, increase in roughness and greater exfoliation availability. The useful deduced information about morphology and composition make the IR laser treatment a simple method for controlling the physical properties of GO film by tailoring the oxygen functional groups, and consequently, for the production of tailor-made highly conductive and defect-free graphene-like materials or GO composites with metals and organic molecules or GO doped with heteroatoms.

Graphene oxide layers modified by irradiation with 1.0 MeV Au+ ions

Graphene oxide (GO) foils were modified by irradiation using 1.0 MeV Au+ ions, and their elemental composition before and after the ion irradiation was investigated using Rutherford back‐scattering spectroscopy (RBS). The surface morphology was studied using SEM, and changes in elemental composition and structure of GO in shallow subsurface were characterized by various spectroscopy techniques including X‐ray photoelectron spectroscopy and Raman spectroscopy. Electrical properties were determined using standard 2‐point method. The analyses indicate that the Au irradiation up to 1.0 × 1015 cm−1 results in removal of oxygen functionalities and growth of graphene domains, leading to a surface conductivity increase dependent on the applied ion fluence. The Au irradiation with excessive ion fluencies leads to the amorphization of GO foil structure.

Graphene oxide layers modified by irradiation with 1.2 MeV He+ ions

The irradiation with 1.2 MeV He+ ions to various fluences was successfully used for modification of graphene oxide (GO). The elemental composition of the GO foils before and after He+ ion irradiation was investigated using Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis. The chemical composition and structural changes of the GO foil surface were characterized by X-Ray Photoelectron and Raman spectroscopy and changes in the electrical properties was studied by standard two point method. The obtained data indicate the removal of oxygen functionalities and growth of the graphene domains on the GO surface that leads to the improvement of surface conductivity which is a growing function of the ion fluence.

Physical investigations on the radiation damage of graphene oxide by IR pulsed laser

Graphene oxide foils were irradiated by Nd:YAG laser at the moderated intensities of the order of 108 W/cm2 in vacuum. Measurements of atomic emission during the laser irradiation were performed with ion collectors and mass spectrometry, demonstrating a strong emission of carbon, oxygen and hydrogen atoms. Further investigations of the irradiated graphene oxide foils were carried out on pristine and laser irradiated samples by using Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. Results indicate that graphene oxide losses oxygen and hydrogen during the irradiation, changing its carbon content and its chemical and physical properties.

Laser modification of graphene oxide layers

The effect of linearly polarized laser irradiation with various energy densities was successfully used for reduction of graphene oxide (GO). The ion beam analytical methods (RBS, ERDA) were used to follow the elemental composition which is expected as the consequence of GO reduction. The chemical composition analysis was accompanied by structural study showing changed functionalities in the irradiated GO foils using spectroscopy techniques including XPS, FTIR and Raman spectroscopy. The AFM was employed to identify the surface morphology and electric properties evolution were subsequently studied using standard two point method measurement. The used analytical methods report on reduction of irradiated graphene oxide on the surface and the decrease of surface resistivity as a growing function of the laser beam energy density.

The stopping power and energy straggling of light ions in graphene oxide foils

Energy-loss and straggling experiments were performed using 2–4MeV 1H+ and 7.4–9.0MeV 4He2+ ions in graphene oxide foils by the transmission technique. The thickness of the graphene oxide foils was determined using a detailed image analysis of a graphene oxide cut, which was used to refine the graphene oxide density. The density was determined by the standard technique of micro-balance weighing. The stoichiometry of the graphene oxide foils before the irradiation was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA) using 2 and 2.5MeV 4He+. The measured energy stopping powers for hydrogen and helium ions in graphene oxide were compared with the predictions obtained from the SRIM-2013 code. The energy straggling was compared with that calculated using Bohr’s, Bethe-Livingston and Yang predictions.The results show that the stopping power of graphene oxide foils irradiated by both ion species decreases with increasing energies, the differences between the measured and predicted values being below 3.8%. The energy straggling determined in our experiment is higher than Bohr’s and Bethe-Livingston predicted values; the predictions by Yang are in better agreement with our experiment.

Graphene oxide layers modified by light energetic ions

In this paper, the effect of light ion irradiation on graphene oxide foil structure and composition was studied. Due to the excellent properties of graphene based materials suitable for application in electronics, optoelectronics, micro-mechanics and space technologies, the interaction of energetic ions with graphene based structures is worth studying. From the fundamental point of view, it is also interesting to get information about graphene oxide structure modification and the possible functional properties after irradiation by energetic ions. The light ion irradiation of graphene oxide (GO) foil was performed using 2.5 MeV H+ and 5.1 MeV He2+ ions. The change in the elemental composition of the GO foils after ion irradiation was investigated using Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis. The influence of ion irradiation was further studied by microscopy methods. The chemical composition and structural changes of the GO foil surface were characterized by spectroscopy techniques including XPS, FTIR and Raman spectroscopy. Although the results of ion beam analysis indicated no significant compositional changes in the bulk of GO foils connected to ion irradiation, XPS, ATR-FTIR and Raman spectroscopy revealed reduction and removal of oxygen functionalities on the surface of graphene oxide. This reduction leads to a surface resistivity decrease after ion irradiation dependent on the ion species, fluence and energy.

Fullerene C60, Graphene-Oxide and Graphene-Oxide Foil with Fullerene and their Bromination

A direct reaction with liquid bromine was used to prepare bromofullerene C60Br14-18. The brominated derivative reacted with previously prepared graphene-oxide (hereinafter GO), according to a method described by Hummer. The same method was used to oxidize graphite alone. The prepared graphite fullerene foil was brominated with liquid bromine and the graphene-oxide foil was reacted with bromofullerene. FT-IR analysis of all the obtained products was performed and also TGA analysis to investigate particularly their thermal stability. The brominated products demonstrate lower thermal effects when thermally decomposed which is caused by the retarding ability of bromine.

Exhaust gas calorimeter for internal combustion engines : J. S. Nicholson and T. B. Morley.( Engin., xciii, 721)

Energy-loss and straggling experiments were performed using 2–4 MeV 1H+ and 7.4–9.0 MeV 4He2+ ions in graphene oxide foils by the transmission technique. The thickness of the graphene oxide foils was determined using a detailed image analysis of a graphene oxide cut, which was used to refine the graphene oxide density. The density was determined by the standard technique of micro-balance weighing. The stoichiometry of the graphene oxide foils before the irradiation was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA) using 2 and 2.5 MeV 4He+. The measured energy stopping powers for hydrogen and helium ions in graphene oxide were compared with the predictions obtained from the SRIM-2013 code. The energy straggling was compared with that calculated using Bohr’s, Bethe-Livingston and Yang predictions.The results show that the stopping power of graphene oxide foils irradiated by both ion species decreases with increasing energies, the differences between the measured and predicted values being below 3.8%. The energy straggling determined in our experiment is higher than Bohr’s and Bethe-Livingston predicted values; the predictions by Yang are in better agreement with our experiment.