Optical Properties Of Graphene Oxide Research Articles

Variable Angle Spectroscopic Ellipsometry Characterization of DMOAP-Functionalized Graphene Oxide Films

In our research, we investigated the optical properties of Graphene Oxide (GO) films functionalized with N,N-Dimethyl-N-octadecyl(3-aminopropyl)trimethoxysilyl chloride (DMOAP) using Variable Angle Spectroscopic Ellipsometry (VASE). We found that after the functionalization process, there was a notable increase in the thickness of the GO films. Additionally, there were observable changes in the Lorentz oscillator parameters, signaling modifications in the electronic transitions and structural properties of the films. Our results indicate that the functionalization with DMOAP not only impacts the electronic conjugation within the GO structures but also enhances the optical conductivity of the films, which is a finding of significant importance for potential applications in electronics, photonics, and materials science.

A fundamental study on the electronic and optical properties of graphene oxide under an external electric field

In this work, we study the impact of the external electric field [Formula: see text] on graphene oxide (GO) layer to improve and optimize its electronic and optical properties, as a result to enhance optoelectronic device technology applications. A three-dimensional [Formula: see text] applied on GO will be examined using the density functional theory (DFT). The [Formula: see text] causes significant modifications to the electronic and optical properties of GO. When increasing the [Formula: see text], a global increase is noted in the bandgap in the x- and y-directions. As for the z-direction, the bandgap energy of GO decreases for an increasing [Formula: see text]. The absorption coefficient ([Formula: see text]) peaks intensities decreased in both visible and ultraviolet (UV) ranges by the effect of the [Formula: see text] applied in the x-direction, and were increased when the [Formula: see text] is applied in the y- and z-directions. It was found that, the electronic and optical properties of GO material, could be controlled by the effects of the [Formula: see text] and by its direction.

Simple preparation of graphene oxide with a modified Hummer's method

Graphene oxide (GO) has gained a lot of interest in recent years as a key precursor and a derivative of graphene. The GO was retrieved from graphite flakes using a modified Hummer's approach that differed from the normal Hummer's method. GO-method 1 using sodium nitrate and GO-method 2 not using sodium nitrate (NaNO3). Used approach is chemical exfoliation, where chemicals are used to intercalate between the graphene layers and expand the interlayer spacing. This expansion weakens the van der Waals forces, making it easier to separate the layers. GO-method 1 and GO-method 2 run on ultrasound and dry. Increasing the ultrasonic process of the procedure reduces the preparation time for graphene oxide compared to the original Hummer’s method. The X-Ray Diffractometer result of GO-method 2 shows the diffraction peaks at 2q at 11.06˚ and 42.24˚ which corresponds to graphene oxide. Raman spectroscopy and UV-visible spectrophotometry were used to investigate the molecular structure and optical properties of graphene oxide, respectively. Field Emission Scanning Electron Microscope of GO to perform elemental mapping on graphene samples and Brunauer Emmet Teller (BET) for surface area determination and pore size distribution results found that GO-method 1 and GO-method 2 corresponds to graphene oxide, which has a macroporous size, and the adsorption response is more respectively.

Influence of gamma radiation on structure, morphology, and optical properties of GO and GO/PVA nanocomposite

In this work, graphene oxide (GO) was prepared by modified Hummer's method and mixed with polyvinyl alcohol (PVA) polymer at different weight concentrations (1 wt % and 5 wt %) and dried at room temperature. The prepared GO and GO/PVA nanocomposites were exposed to gamma (γ) radiation at different doses (1, 50 and 150 Mrad). Changes in the structure, optical properties and morphology were observed after being exposed to radiation at different doses. The structural change in the nanocomposites was determined by X-Ray diffraction (XRD). Morphological changes in the nanocomposites were characterized using transmission electron microscopy (TEM). Elemental analysis was carried out with an energy-dispersive spectrometer (EDS). The optical properties of the samples were studied by ultraviolet–visible (UV–Vis) spectroscopy. In this study, decomposition and oxidation of residual graphite under the influence of γ radiation were observed. The band gap value of samples decreased with the increase of gamma radiation.

Electronic correlations enhance optical absorption in graphene oxide-modified methylammonium lead iodide perovskite

We reveal unusual optical changes accompanied by spectral weight transfer analysis in methylammonium lead iodide (MAPbI3) as a function small fraction of graphene oxide (GO) concentrations using spectroscopic ellipsometry. Interestingly, we observe the tuneable optical properties of MAPbI3 due to the electronic correlation effect induced by GO using spectral weight transfer analysis. The increase of absorption in the MAPbI3 layer indicates a decrease in the number of holes due to the migration of these holes to the GO layer, suggesting the hole transport properties of GO. This work is the first to study the optical properties of GO combined with MAPbI3, which provides critical information that will be of great interest in the future development of high-performance PSCs, as well as how they reconcile several experimental studies that have demonstrated the positive impact of GO on charge extraction.

Synthesis and characterization of linear/nonlinear optical properties of graphene oxide and reduced graphene oxide-based zinc oxide nanocomposite

In this paper, we aimed to investigate the linear and nonlinear optical properties of GO-ZnO and RGO-ZnO nanocomposites in comparison with pure GO and reduced graphene oxide (RGO). For this purpose, GO, RGO, GO-ZnO, and RGO-ZnO were synthesized and characterized by Fourier transform infrared (FT-IR), Ultraviolet–Visible (UV–Vis) absorption, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD and EDX analysis indicated the reduction of GO as well as the successful synthesis of GO-ZnO and RGO-ZnO nanocomposites. The FT-IR spectroscopy showed that absorption bands were at 3340 cm−1, 1630 cm−1, 1730 cm−1 and 480 cm−1 related to OH, C=C, C=O, and Zn–O stretching vibrations, respectively. The direct band gaps of GO, RGO, GO-ZnO and RGO-ZnO from UV–Vis spectra were at 3.36, 3.18, 3.63 and 3.25 eV, sequentially. Moreover, the third-order nonlinear optical properties were investigated using a z-scan technique with Nd: YAG laser (532 nm, 70 mW). It can be seen that the nonlinear absorption coefficient value (upbeta ) increased from 5.3 × 10–4 (GO) to 8.4 × 10–3 cm/W (RGO-ZnO). In addition, nonlinear refractive index (n2) of the GO, RGO, GO-ZnO, and RGO-ZnO was obtained as 10.9 × 10–10, 14.3 × 10–10, 22.9 × 10–10, and 31.9 × 10–10 cm2/W respectively.

Reaction-Time-Dependent Opto-Electrical Properties of Graphene Oxide

The reaction-time-dependent synthesis of graphene oxide (GO) was carried out using a modified Hummer’s method. The drop-casting method was used to coat GO films on a glass substrate. Various techniques, including scanning electron microscopy, X-ray diffraction, UV–Vis spectroscopy (UV–Vis), Fourier transform infrared spectroscopy, and current–voltage characteristics, were performed to obtain the morphological, structural, optical, and electrical properties of GO. Morphological structural observations revealed that more oxygen functional groups were present as the reaction time increased from 24 to 96 h, which was confirmed by the optical properties of GO thin films. The resistivity of the as-deposited films increased from 9.74 × 106 to 26.85 × 106 Ω·cm as the reaction time increased. The optimized reaction time with a resistivity of 12.13 × 106 Ω·cm was 48 h, as demonstrated by morphological and optical data.

Oxide ion polarizability, optical basicity, and metallization criterion of GO-coated Nd2O3 (NPs) - TeO2 glass for linear optical fibre

The versatility of graphene oxide (GO) as coating materials on the glass surface is a new revolution in the advanced glass era. In this work, GO liquid solution was prepared by using electrochemical exfoliation in an electrolyte solution assisted by different surfactants. Meanwhile, a glass series was prepared by using the conventional meltquenched technique. A low-cost and simple spray deposition technique was used to deposit the GO on the glass sample. The obtained glass series was denoted as GO coated TNd (NPs), meanwhile, the uncoated glass was labelled as uncoated TNd (NPs). The linear optical properties of GO coated TNd (NPs) glass series was determined using UVVis spectrophotometer and utilizing the Lorentz-Lorentz equation to determine the value of polarizability. X-ray diffraction spectra revealed the amorphous structural characteristics of the glass series. The SEM morphological image revealed the variation of GO distribution on the glass surface due to the agglomeration and inhomogeneity of GO distribution on the glass surface. The homogeneity of GO distribution on the glass surface is negligible in this work as we focus solely on the effect of GO on glass properties. According to the observations, the value of GO-coated TNd (NPs) is in the range 3.4531- 3.8549 Å and uncoated TNd (NPs) is in the range 2.709- 2.774 Å. Meanwhile, the optical basicity value ranges from 1.220 to 1.262. These results demonstrate that the polarizability of oxide ions and optical basicity values of the GO coated TNd (NPs) glass series was higher than the uncoated TNd (NPs) glass. The metallization criterion for the GO-coated TNd (NPs) glass system is in the range of 0.3 < M < 0.4. Based on these results, the obtained glasses are promising in linear optical glass fibre.

Photoluminescence and Fluorescence Quenching of Graphene Oxide: A Review.

In recent decades, photoluminescence (PL) material with excellent optical properties has been a hot topic. Graphene oxide (GO) is an excellent candidate for PL material because of its unique optical properties, compared to pure graphene. The existence of an internal band gap in GO can enrich its optical properties significantly. Therefore, GO has been widely applied in many fields such as material science, biomedicine, anti-counterfeiting, and so on. Over the past decade, GO and quantum dots (GOQDs) have attracted the attention of many researchers as luminescence materials, but their luminescence mechanism is still ambiguous, although some theoretical results have been achieved. In addition, GO and GOQDs have fluorescence quenching properties, which can be used in medical imaging and biosensors. In this review, we outline the recent work on the photoluminescence phenomena and quenching process of GO and GOQDs. First, the PL mechanisms of GO are discussed in depth. Second, the fluorescence quenching mechanism and regulation of GO are introduced. Following that, the applications of PL and fluorescence quenching of GO–including biomedicine, electronic devices, material imaging–are addressed. Finally, future development of PL and fluorescence quenching of GO is proposed, and the challenges exploring the optical properties of GO are summarized.

Development of Localized Surface Plasmon Resonance-Based Optical Fiber Biosensor for Immunoassay Using Gold Nanoparticles and Graphene Oxide Nanocomposite Film

In this study, the development of a reflected-type localized surface plasmon resonance (LSPR) based optical fiber biosensor is presented. The gold nanoparticles (AuNPs) and graphene oxide (GO) are sequentially modified on the surface of fiber probes to form a nanocomposite film using self-assembly method. Compared with AuNPs fiber probe, the refractive index sensitivity (RIS) of GO/AuNPs fiber probe is improved from 29.6 nm/RIU to 79 nm/RIU in the refractive index range from 1.33 to 1.38. After that, the fiber probes are immobilized with anti-mouse IgG for the immunoassay, and the response time is 30 minutes. Due to the advantages of good biocompatibility as well as physical and optical properties of GO, the GO/AuNPs fiber probe shows a quicker reaction and larger resonant wavelength shift, which are compared with AuNPs fiber probe in measuring different concentrations of mouse IgG. In addition, the GO/AuNPs fiber probe exhibits a better sensitivity (150.4 nm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> mL <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ), linearity (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.998) and a lower limit of detection (4.3 ng/mL) in a low concentration of mouse IgG detection, which suggests that GO has huge potentials of biosensing applications in the future.

First-principles calculations to investigate the influence of porphyrin substitution on the structural, electronic and optical properties of graphene oxide

The following article aims to investigate the influence of porphyrin (PP) on the crystallinity, electronic structure, and optical properties of graphene oxide (GO), using the density functional theory (DFT). Theoretical calculation indicates that porphyrin substitution brings about significant distortion in the GO sheet. The substitution of porphyrin on the graphene oxide layer (GO-PP), leads to decrease the bandgap of the GO material. After substitution, the absorption coefficient decreases in the UV domain and increases in the visible range. Thus, the observed redshift in absorption peaks upon porphyrin substitution was attributed to the assembly that consists of J-aggregates. In this work, we explore the substitution effect of PP chain on the GO sheet as a window layer, over the power conversion efficiency of solar cells. The substitution of PP chain on the GO sheet improves the degree of power conversion efficiency of solar cells. Further comparison indicates that calculations are consistent with experimental observation, which indicates that DFT calculation at CASTEP code level gives good results of porphyrin substitution on the graphene oxide layer.

Study of Structural and Optical Properties of Graphene Oxide @ Mn-Doped Co3o4 Hybrid Nanocomposite Synthesis by Hydrothermal Route

Study of Structural and Optical Properties of Graphene Oxide @ Mn-Doped Co3o4 Hybrid Nanocomposite Synthesis by Hydrothermal Route

Modification of structure and optical properties of graphene oxide dots, prepared by laser ablation method

Modification of structure, optical and luminescent properties of graphene oxide (GO) by laser ablation at 532 nm during various times was studied. It was shown that after 30 minutes of laser ablation, the average lateral size of GO sheets decreases from 272±120 nm to 62±29 nm. Studies of structural properties by Raman and FTIR spectroscopy and microscopy indicate the reduction and graphitization of GO at laser irradiation times greater than 20 minutes, which leads to an increase in the average crystallite size of sp2 carbon domains and a decrease in the number of GO layers in the resulting particles. The optical density of the resulting GO solutions and the intensity of their fluorescence are also time dependent. After ablation, the GO fluorescence intensity increased by 10, 25, and 36% for 10, 20 and 30 minutes, respectively. In the long-lived luminescence spectrum of GO, a broad emission band was recorded after ablation, whereas for GO before ablation long-lived luminescence was not exhibited.

Silver decorated 2D nanosheets of GO and MoS2 serve as nanocatalyst for water treatment and antimicrobial applications as ascertained with molecular docking evaluation

In this work, synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) was realized through a modified Hummers route. Different concentrations (5 and 10 wt%) of Ag were doped in MoS2 and rGO using a hydrothermal technique. Synthesized Ag-MoS2 and Ag-rGO were evaluated through XRD that confirmed the hexagonal structure of MoS2 along with the transformation of GO to Ag-rGO as indicated by a shift in XRD peaks while Mo–O bonding and S=O functional groups were confirmed with FTIR. Morphological information of GO and formation of MoS2 nanopetals as well as interlayer spacing were verified through FESEM and HRTEM respectively. Raman analysis was employed to probe any evidence regarding defect densities of GO. Optical properties of GO, MoS2, Ag-rGO, and Ag-MoS2 were visualized through UV–vis and PL spectroscopy. Prepared products were employed as nanocatalysts to purify industrial wastewater. Experimental results revealed that Ag-rGO and Ag-MoS2 showed 99% and 80% response in photocatalytic activity. Besides, the nanocatalyst (Ag-MoS2 and Ag-rGO) exhibited 6.05 mm inhibition zones against S. aureus gram positive (G+) and 3.05 mm for E. coli gram negative (G-) in antibacterial activity. To rationalize biocidal mechanism of Ag-doped MoS2 NPs and Ag-rGO, in silico molecular docking study was employed for two enzymes i.e. β-lactamase and D-alanine-D-alanine ligase B (ddlB) from cell wall biosynthetic pathway and enoyl-[acylcarrier-protein] reductase (FabI) from fatty acid biosynthetic pathway belonging to S. aureus. The present study provides evidence for the development of cost-effective, environment friendly and viable candidate for photocatalytic and antimicrobial applications.

Preparation, characterization, and nonlinear optical properties of graphene oxide thin film doped with low chirality metallic SWCNTs

We present non-linear optical properties of graphene oxide (GO) doped with low chirality metallic single walled carbon nanotubes (m-SWCNTs) thin films. The weight percentage of the m-SWCNTs was 5, 10, and 20 wt%. High-resolution transmission electron microscope (HRTEM), high resolution scanning electron microscope (HRSEM), Raman, and UV–vis spectroscopy were used to characterize the prepared samples. We have investigated their nonlinear optical properties using open and closed Z-scan technique at Nd:YAG laser at 1064 nm laser pulses (7 ns, 10 Hz). The nonlinear absorption coefficient β, nonlinear refractive index n2, and third order nonlinear susceptibility χ3 were calculated. The results show that all samples exhibit reverse saturable absorption (RSA) because of increasing metallicity and/or partial reduction of GO during laser illumination. The nonlinearity response of the GO/m-SWCNT films increase as the m-SWCNTs percentage increases. The high non-linear optical parameters of the GO/m-SWCNTs films make them as superior candidates for near-infrared (NIR) laser protection applications.

The effect of spray cycles on the morphological, structural, and optical properties of rGO thin film deposited using spray pyrolysis technique

This study proposed a facile and cost-effective approach to synthesize reduced graphene oxide (rGO) thin film from graphene oxide (GO) water dispersion. The rGO thin films were deposited on glass substrates via spray pyrolysis technique (SPT) by using different numbers of spray cycles (i.e. 2 to 10). The structure, morphology, thickness, and optical properties of GO and rGO thin films were characterized using different techniques. The optical analysis showed that the energy band gap of GO and rGO thin films reduced from 4.2 to 3.27 eV as the spray cycles were increased from 2 to 10, which confirms the effect of surface coating thickness on conductivity. To test the performance of the rGO thin film as a UV photodetector device, metal-semiconductor-metal (MSM) configuration was achieved by incorporating Al metal using RF sputtering on the thin film sample prepared with 10 spray cycles. For the device, the photoresponse (R) were found to be 0.0038, 0.0084, 0.01700, and 0.0284 (A/W), while photodetector gain (G) values were 1.956, 2.05, 2.15, and 2.31 at bias voltages of 1, 2, 3, and 4 V, respectively. At the same range of bias voltages, the rise times of the photodetector were 0.08, 0.075, 0.055, and 0.055 s, while the fall time were 0.055, 0.066, 0.06 and 0.06 s, respectively, under 375 nm UV illumination (0.37 mW/cm2). The maximum sensitivity (S%) was found to be 131.84 at 4 V. The photoelectric properties and photodetection performances indicate that rGO thin film deposited on glass substrate by SPT could be a potential candidate for the development of advanced MSM optoelectronic devices.

Graphene Oxide Films for Ultra-Thin Optics and Linear and Nonlinear Integrated Photonic Circuits

With superior optical properties, high flexibility in engineering its material properties, and strong capability for large-scale on-chip integration, graphene oxide (GO) is an attractive solution for on-chip integration of two-dimensional (2D) materials to implement functional integrated photonic devices capable of new features. Over the past decade, integrated GO photonics, representing an innovative merging of integrated photonic devices and thin GO films, has experienced significant development, leading to a surge in many applications covering almost every field of optical sciences. This paper reviews the recent advances in this emerging field, providing an overview of the optical properties of GO as well as methods for the on-chip integration of GO. The main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. The open challenges as well as the potential for future improvement are also discussed.

Competitive Adsorption on Nanomaterials for Human Papillomavirus 16 L1 Protein Sensitive Detection

Human papillomavirus (HPV) L1 protein is a biomarker of HPV infection. The identification of HPV L1 protein provides valuable information regarding the viral infection status, reflect the status of HPV virus replication in cervical cells, and help understand cervical lesions Fade and progress. Graphene oxide is an important nanomaterial. Owing to the optical properties of graphene oxide (GO) itself and the interaction between GO and HPV16 L1 nucleic acid aptamer, we established a method for quantitative detection of HPV16 L1 protein by UV absorption spectrophotometry. The recovery rate of the method is 87%–102%, and the limit of detection is 2 pg/mL. We analyzed the HPV16 L1 protein quantitatively in clinical samples by adopting this method. The current method is simple and has promising reliability and profound sensitivity.

Graphene Oxide for Integrated Photonics and Flat Optics.

With superior optical properties, high flexibility in engineering its material properties, and strong capability for large-scale on-chip integration, graphene oxide (GO) is an attractive solution for on-chip integration of 2D materials to implement functional integrated photonic devices capable of new features. Over the past decade, integrated GO photonics, representing an innovative merging of integrated photonic devices and thin GO films, has experienced significant development, leading to a surge in many applications covering almost every field of optical sciences such as photovoltaics, optical imaging, sensing, nonlinear optics, and light emitting. This paper reviews the recent advances in this emerging field, providing an overview of the optical properties of GO as well as methods for the on-chip integration of GO. The main achievements made in GO hybrid integrated photonic devices for diverse applications are summarized. The open challenges as well as the potential for future improvement are also discussed.

Dependence of linear and non-linear optical properties to sp3 domains level and edges length in graphene-based nanomaterials

In this work, a single-layer of graphene oxide (GO), reduced graphene oxide (r-GO), and graphene quantum dot (GQD) nanosheets were synthesized using a modified Hummers' method. AFM and FTIR spectroscopies were used to confirm single-layer graphene synthesis and proper reduction process. Photoluminescence (PL) and Z-scan characterizations showed a high existence of linear and non-linear optical properties in these nanomaterials. PL spectra of r-GO showed a peak at 665 nm, but an appeared blueshift in the PL spectrum of GO (600 nm) and GQD (500 nm) nanosheets indicate a bandgap opening in their band structures. According to Raman results, the I(D)/I(G) intensity ratio of GO is bigger than r-GO, which can be assigned to higher linear optical properties of GO than r-GO and higher non-linear optical properties of r-GO than GO. Finally, our results demonstrated that edges length and functional groups on the edges define the appearance of linear and non-linear optical properties in graphene-based nanomaterials, and these properties can be manipulatable in terms of oxidation/reduction level, surface area size and edge length.