Graphene Oxide Nanostructures Research Articles

Simultaneous microwave-assisted reduction and B/N co-doping of graphene oxide for selective recognition of VOCs

The influence of heteroatom domains on the volatile organic compound (VOC) detection properties of B/N co-doped graphene oxide nanostructures is investigated by using different boron (B) and nitrogen (N) sources.

Influence of nano-structured graphene oxide on strength and performance characteristics of high strength fiber reinforced self compacting concrete

Nowadays nanomaterial is used in concrete as Graphene Oxide (GO). Graphene oxide may have more application and impact in the construction industry in the coming future. It has good dispersibility properties than other remaining nanomaterials like Nano silica, Nano alumina, and also Carbon nanotubes. Adopting this nanomaterial, not only improves the strength but also improves the durability properties. In our work seven mixes were prepared by adding Graphene Oxide in SCC with different proportions (0%,0.025%,0.05%,0.075%, and 0.1% by weight of cement), SCC with only steel fiber (0.25% by volume of concrete), and SCC with steel fiber (0.25% by volume of concrete) plus optimum GO(0.075% by weight of cement). In these mixes, the River sand 50% was replaced by M-sand as a renewable material. The Rheological, Mechanical, and durability tests were carried out on all seven mixes. Compared with all other mixes, the mix which contains 0.075 %GO dosage and optimum steel fiber is shown good results in Compressive. flexural and split tensile strength. In the assessment of the quality of concrete carried out by using ultrasonic pulse velocity test the concrete mix with only 0.075 %GO addition and with no addition of steel fiber results in a better quality of concrete compared with control concrete and Graphene oxide is structurally characterized by means of XRD and SEM.

Improvement in bioavailability of curcumin within the castor‐oil based polyurethane nanocomposite through its conjugation on the surface of graphene oxide nanosheets

AbstractRecently biocompatible polyurethane (PU) films, made from renewable bioactive compounds have been introduced as a feasible option to accelerate wound healing process. In this work, graphene oxide (GO) nanostructures were applied as a practical nanocarrier system to enhance the bioavailability of curcumin within castor‐oil based PU elastomer nanocomposites. Successfully modification of GO nanosheets with curcumin (C‐GO) were confirmed by FT‐IR, XRD, TGA, Raman spectroscopy, and FE‐SEM microscopy techniques. FE‐SEM images demonstrated a good dispersion quality of C‐GO nanosheets in the PU matrix, demonstrating the enhanced bioavailability of curcumin. Based on XRD diffractograms, PU/C‐GO nanocomposite showed a lower crystallinity and microphase‐separation degree compared to blank PU sample. This finding is probably originated from the amphiphilic properties of C‐GO which provides possibility of good interactions with hard and soft domains in PU backbone. Moreover, compared to PU/GO nanocomposite, the surface modification of GO with curcumin increased the tensile strength and Young's modulus of PU/C‐GO nanocomposite to 4.92 and 44.49 MPa, respectively. The in vitro MTT assay revealed a significant viability for L929 fibroblast cells in exposure with PU/C‐GO film. Besides, the results of in vivo wound healing evaluation on the mouse model indicated that the PU/C‐GO sample could accelerate the healing rate by promoting the proliferation and re‐epithelialization of fibroblast cells in the wound site. Thus, it is suggested that the PU/C‐GO nanocomposite film may has a potential and promising application as a wound dressing.

Enhanced thermal and electrical properties by Ag nanoparticles decorated GO-CNT nanostructures in PEEK composites

A nanostructure of graphene oxide (GO) and carbon nanotubes (CNTs) decorated with silver nanoparticles (AgGNT) has been prepared via a molecular-level-mixing (MLM) method followed by a subsequent freeze-drying and reduction process. The obtained well-dispersed AgGNT nanostructures were then applied as fillers to reinforce the poly(ether ether ketone) (PEEK) matrix. AgGNT-PEEK composites have then demonstrated excellent electrical and thermal conduction performances as well as high thermal durability compared with pure PEEK and its pure Ag or GO-CNT (GNT) enhanced composites. Owing to the unique morphology of AgGNT nanostructures, which made them uniformly dispersed in the PEEK matrix and formed a 3D network structure, the AgGNT-PEEK composites displayed 60% higher thermal conductivity and around 109 times better electrical conduction performance than pure PEEK, and superior thermal durability even above the melting temperature of pure PEEK. Thus, the AgGNT-PEEK composites have shown great potential for applications such as semiconductors, high-temperature electrical applications, aerospace, and automobile materials.

Compulsive malposition of birnessite slab in 2D-Parallel birnessite on β-MnO2 networks for enhanced pseudocapacitance performances

Abstract High electrochemically active birnessite is always desirable pseudocapacitive material for supercapacitor. Here, two-dimensional (2D) compulsive malposition parallel birnessite standing on β-MnO2 interconnected networks have been designed. Due to the restriction of β-MnO2, compulsive malposition, slippage of MnO6 slab, occurred in birnessite resulting in weaken binding force between birnessite slab and interlayer cations, which enhanced their electrochemical performances. Additionally, the electrical conductivity of the structure was largely promoted by the 2D charge transfer route and double-exchange mechanism in birnessite, also leading to desirable electrochemical properties. Based on the fraction of as-prepared nanostructure, the parallel birnessite exhibited good pseudocapacitance performance (660 ​F ​g−1) with high rate capability. In addition, the asymmetric supercapacitor assembled by reduced graphene oxide (RGO) and as-prepared nanostructure, which respectively served as the negative and positive electrode, delivered an energy density of 33.1 ​Wh kg−1 and a maximum power density of 64.0 ​kW ​kg−1 with excellent cycling stability (95.8% after 10000 cycles). Finally, the study opens new avenues for synthesizing high electrochemically active birnessite structure for high-performance energy storage devices.

Ionic Transport Triggered by Asymmetric Illumination on 2D Nano-Membrane.

Ionic transport and ion sieving are important in the field of separation science and engineering. Based on the rapid development of nanomaterials and nano-devices, more and more phenomena occur on the nanoscale devices in the field of thermology, optics, mechanics, etc. Recently, we experimentally observed a novel ion transport phenomenon in nanostructured graphene oxide membrane (GOM) under asymmetric illumination. We first build a light-induced carriers’ diffusion model based on our previous experimental results. This model can reveal the light-induced ion transport mechanism and predict the carriers’ diffusion behavior under different operational situations and material characters. The voltage difference increases with the rise of illuminate asymmetry, photoresponsivity, recombination coefficient, and carriers’ diffusion coefficient ratio. Finally, we discuss the ion transport behavior with different surface charge densities using MD simulation. Moderate surface charge decreases the ion transport with the same type of charge due to the electrostatic repulsion; however, excess surface charge blocks both cation and anion because a thicker electrical double layer decreases effective channel height. Research here provides referenced operational and material conditions to obtain a greater voltage difference between the membrane sides. Also, the mechanism of ion transport and ion sieving can guide us to modify membrane material according to different aims.

The effects of bimodal action of photodynamic and photothermal therapy on antimicrobial and shear bond strength properties of orthodontic composite containing nano-graphene oxide

Background: White spot lesions are a common adverse effect of fixed orthodontic treatment and represent the main challenge to achieving esthetic appearance. The purpose of the current study was to evaluate physico-mechanical and antimicrobial potency of orthodontic composite (OC; Transbond XT) containing nano-structured graphene oxide (nGO) (OC-nGO) as a novel composite following photodynamic therapy (PDT) and photothermal therapy (PTT) against Streptococcus mutans. Materials and methods: Following preparation of OC-nGO, shear bond strength (SBS) and adhesive remnant index (ARI) of the test OC-nGO (containing 1, 2, 5, and 10% wt. nGO) were measured using a universal testing machine and stereomicroscope, respectively. The antimicrobial activities of test OC contained different concentrations of nGO were determined by disk agar diffusion (DAD), biofilm formation inhibition, and eluted components assays. After continuously rinsed in the aging process (up to 180 days), the antimicrobial activity of OC-nGO containing the highest concentration of nGO which had simultaneously the highest antimicrobial activity and SBS value were determined by DAD, biofilm formation, metabolic activity, and gtfB gene expression assays following photo-activation using diode laser irradiation against S. mutans. Data were analyzed using One-way Analysis of Variance (ANOVA). The Bonferroni post hoc test was used for comparison between the experimental groups. The significant difference was considered at P values < 0.05. Results: OC with 5% wt. nGO showed simultaneously the highest SBS value (10.64 ± 2.76 MPa, P < 0.05) an antimicrobial and anti-biofilm activities. The OC-nGO in all test concentrations of nGO had ARI scores as same as control group (Transbond XT without the nGO) (P < 0.05). In microbial biofilm formation and gene expression assays, the reduction of photothermal disinfection and anti-virulence activities of the 5% wt. OC-nGO against test bacterium was associated with the time of aging process, so they were reduced significantly up to day 150. Diode laser irradiated 5% wt. OC-nGO suppressed 15.6 and 8.1-fold gtfB mRNA expressions in the biofilm growth of the S. mutans at days 120 and 150 of rinsing (P < 0.05). Microbial biofilm formation and gtfB gene expression in S. mutans at day 180 following PAD had a high level of similarity with OOC as the control group. 5% wt. OC-nGO following photo-activation was not colonized by the S. mutans at day 90 and significant suppressed 91.98% and 76.37% of S. mutans biofilm formation at day 120 and 150, respectively (both P < 0.05). From day 120 onwards, metabolic activity was progressively increased on laser-irradiated 5% wt. OC-nGO discs compared to the control group (OC alone). Photo-activated OC-nGO containing 5% wt. nGO suppressed 86.94% and 46.82% metabolic activity of the S. mutans at days 120 and 150 of rinsing (both P < 0.05). Conclusions: Our data support that the photo-activated 5% wt. OC-nGO can serve as an orthodontic composite/adhesive additive to control cariogenic bacterial biofilms.

Poly(2-ethyl-2-oxazoline) functionalized reduced graphene oxide: Optimization of the reduction process using dopamine and application in cancer photothermal therapy

The high near infrared (NIR) absorption displayed by reduced graphene oxide (rGO) nanostructures renders them a great potential for application in cancer photothermal therapy. However, the production of this material often relies on the use of hydrazine as a reductant, leading to poor biocompatibility and environmental-related issues. In addition, to improve rGO colloidal stability, this material has been functionalized with poly(ethylene glycol). However, recent studies have reported the immunogenicity of poly(ethylene glycol)-based coatings. In this work, the production of rGO, by using dopamine as the reducing agent, was optimized considering the size distribution and NIR absorption of the attained materials. The obtained results unveiled that the rGO produced by using a 1:5 graphene oxide:dopamine weight ratio and a reaction time of 4 h (termed as DOPA-rGO) displayed the highest NIR absorption while retaining its nanometric size distribution. Subsequently, the DOPA-rGO was functionalized with thiol-terminated poly(2-ethyl-2-oxazoline) (P-DOPA-rGO), revealing suitable physicochemical features, colloidal stability and cytocompatibility. When irradiated with NIR light, the P-DOPA-rGO could produce a temperature increase (ΔT) of 36 °C (75 μg/mL; 808 nm, 1.7 W/cm2, 5 min). The photothermal therapy mediated by P-DOPA-rGO was capable of ablating breast cancer cells monolayers (viability < 3%) and could reduce heterotypic breast cancer spheroids' viability to just 30%. Overall, P-DOPA-rGO holds a great potential for application in breast cancer photothermal therapy.

Polyaniline decorated graphene oxide on sulfonated poly(ether ether ketone) membrane for direct methanol fuel cells application

AbstractIn direct methanol fuel cells (DMFC), methanol crossover is a major issue which has reduced the performance of polymer electrolyte membrane (PEM) for energy generation. In this study, graphene oxide (GO) and conductive polyaniline decorated GO (PANI‐GO) were used as additives in fabrication of sulfonated poly(ether ether ketone) (SPEEK) nanocomposite PEM membrane to reduce methanol crossover. PANI‐GO was synthesized by in situ polymerization method and the formation of PANI coated GO nanostructures was confirmed by surface morphology and crystallinity analysis. The membrane morphology and topography analysis confirmed that GO and PANI‐GO were well dispersed on the surface of SPEEK membrane. 0.1 wt% PANI‐GO modified SPEEK nanocomposite membrane exhibited the highest water uptake and ion exchange capacity of 40% and 1.74 meq g−1, respectively. The oxidative stability of the nanocomposite membranes also improved. Lower methanol permeability of 4.33 × 10−7 cm−2S−1 was noticed for 0.1 wt% PANI‐GO modified SPEEK membrane. PANI‐GO modified SPEEK membrane enhanced the proton conductivity, which was due to the existence of acidic and hydrophilic group present in PANI and GO. PANI‐GO modified SPEEK membrane held higher selectivity of 1.94 × 104 S cm−3 s−1. Overall, these studies revealed that PANI‐GO modified SPEEK membrane is a potential material for DMFC applications.

Modification and superhydrophilization of electrospun polyvinylidene fluoride membrane using graphene oxide-chitosan nanostructure and performance evaluation in oil/water separation

Surface properties of fish scales have inspired many research works aiming at fabrication of membranes with specific surface wettability that have been applied vastly for treating oily wastewater. The goal of this study was wettability modification of an electrospun nanofibrous membrane based on polyvinylidene fluoride (PVDF) to make it an effective filtering media for the field of oil-water separation. Surface modification of highly hydrophobic PVDF membrane was performed by coating it with chitosan–graphene oxide nanostructures. The modified membrane acquired superhydrophilicity and underwater superoleophobicity properties. Characteristics of the membrane were determined and analyzed using SEM, FT-IR, XRD, AFM and EDX. Contact angle measurements were used to determine membrane wettability. The fabricated membrane showed zero water contact angle and a maximum oil contact angle of 154°. The modified membrane was tested for separation of some oil/water mixtures under different operating conditions. The measured flux of oil/water mixtures in these tests ranged from 30,120 ± 1154 to 33,637 ± 1328 average of 31,673 ± 1447 Lm−2h−1bar−1 under 0.4 bar pressure difference. The test results revealed excellent oil separation efficiency up to 99% and, superior antifouling properties with no significant change in several cycles of oil/water mixtures separation. Furthermore, the modified membrane could effectively separate oil/water mixtures in a broad pH range and could be used with a high flux recovery ratio.

High sensitivity colorimetric determination of L-cysteine using gold nanoparticles functionalized graphene oxide prepared by photochemical reduction method

This study aimed for the development of a cost effective and efficient method for L-cysteine detection, without employing expensive instrumentation within a short analysis time. The proposed method has been involved in the photochemical preparation of gold nanoparticles and gold nanoparticles on graphene oxide nanostructures. The gold nanoparticles and gold nanoparticles on graphene oxide acted as simple and sensitive nano-sensors for L-cysteine, due to the molecular structure of the L-cysteine presented –NH2 and –SH, which is very attractive for coordination to gold nanoparticles and crosslink gold nanoparticles causing aggregation and color change. By using the gold nanoparticles on graphene oxide as a probe, the colorimetric detection of L-cysteine in a nanomolar order concentration was demonstrated.

Micro Scalable Graphene Oxide Productions Using Controlled Parameters in Bench Reactor.

The detailed study of graphene oxide (GO) synthesis by changing the graphite/oxidizing reagents mass ratios (mG/mROxi), provided GO nanosheets production with good yield, structural quality, and process savings. Three initial samples containing different amounts of graphite (3.0 g, 4.5 g, and 6.0 g) were produced using a bench reactor under strictly controlled conditions to guarantee the process reproducibility. The produced samples were analyzed by Raman spectroscopy, atomic force microscopy (AFM), x-ray diffraction (XDR), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetry (TGA) techniques. The results showed that the major GO product comprised of nanosheets containing between 1–5 layers, with lateral size up to 1.8 µm. Therefore, it was possible to produce different batches of graphene oxide with desirable physicochemical characteristics, keeping the amount of oxidizing reagent unchanged. The use of different proportions (mG/mROxi) is an important strategy that provides to produce GO nanostructures with high structural quality and scale-up, which can be well adapted in medium-sized bench reactor.

Evaluation and determination of occupational and environmental exposure of lead in workplace air and human workers based dispersive ionic liquid solid phase micro extraction in battery manufacturing factories from Iran

The exposure of lead in workplace air and human workers of battery manufacturing factory was evaluated determined by nanotechnology since 2019-2020. Human whole blood (HWB) for subject and healthy peoples (25-55, Men, 40 N) and workplace air (40N) was prepared based on NIOSH sampling. 10 mL of HWB samples added to 20 mg of mixture ionic liquid/ ligand ([HMIM][PF6]/APDC) modified on graphene oxide nanostructures(GONs) at pH=6. After sonication, the lead ions separated/extracted by dispersive ionic liquid solid phase micro extraction (DIL-SPME) and determined by flame atomic absorption spectrometry (F-AAS). All air samples in workplace were analyzed based on NIOSH process. The results showed us the negative correlation between Pb concentration in human blood subject and healthy peoples (r=0.24). The range concentrations of lead in human subject, healthy peoples and workplace air were obtained 193.4-543.7 µg L-1, 85.6-175.9 µgL-1 and 44.7-81.5 µgm-3, respectively. The LOD, linear rang, enrichment factor(EF) and RSD% were achieved 1.25 µg L-1, 5.0- 310 µg L-1, 19.6 and less than 5% by procedure. The method was validated by standard reference material (SRM), the electrothermal atomic absorption spectrometry (ET-AAS) and ICP-MS analyzer for human samples.

Liquid exfoliation of graphene oxide nanoribbons using chemical assisted laser ablation

The interest toward two-dimensional (2D) materials is gradually increasing because of their structure at nanoscale and great importance for electronic and optical applications. In this study, we show the synthesis of graphene oxide (GO) micro-ribbons fabricated by chemical assisted-laser ablation method. In order to confirm the formation of GO, UV-visible spectroscopy (UV-vis) and Raman spectroscopy are used to observe the surface morphological feature and structural details. In addition, a possible mechanism for the growth of GO nanoribbon is discussed. This work indicates a new method to develop GO nanostructures and related nanomaterials.

Chemically Converted Graphene Nanosheets for the Construction of Ion-Exclusion Nanochannel Membranes.

Water and ion transport in nanochannels is an intriguing topic that has been extensively investigated in several energy- and environment-related research fields. Recently developed two-dimensional (2D) materials are ideal building blocks for constructing confined nanochannels by self-stacking. Among these, graphene oxide (GO) is the most frequently employed as the starting material because of its excellent solution processability. Since solvation of the GO nanostructure usually impairs the function of nanochannels, in this study, chemically converted graphene was prepared using a one-step method, to simultaneously acquire the desired stability and functionality of the nanochannels. The confined channels with high charge densities are capable of excluding ∼90% NaCl solutes from water in a pressure-driven filtration process. This surpasses the performance of most GO desalination membranes reported in the literature. Thus, this study provides useful information for the feasible development of ion-exclusion nanochannel membranes based on the proposed nanochannel-confined charge repulsion mechanism.

Designing of cerium phosphate nanorods decorated reduced graphene oxide nanostructures as modified electrode: An effective mode of dopamine sensing

In this study, we have developed a voltametric and amperometric sensor by using cerium phosphate nanorods (CPNR) decorated reduced graphene oxide (RGO) (CPRGO) modified glassy carbon electrode for sensitive and selective detection of dopamine (DA). These nanostructures have been characterized by PXRD, FT-IR, FESEM, HR-TEM, Raman and XPS spectroscopy. Electrochemical performance of electrodes was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor demonstrated the linear range 1 – 10 μM by voltametric and 1–13 μM by amperometric with the detection limit of 0.118 μM (S/N = 3) and 0.109 μM, respectively. Selective detection of DA against glucose and ascorbic acid (AA) was performed by amperometry. In present sensing method of DA in real biological fluid blood serum separated from human blood sample was applied to get recovery between 99.4 and 100.66 %. Our results show that electrode modified with these nanostructures can serve as the most sensitive and selective detection for DA in neurological environment.

Phytogenic Synthesis of Pd-Ag/rGO Nanostructures Using Stevia Leaf Extract for Photocatalytic H2 Production and Antibacterial Studies.

Continuously increasing energy demand and growing concern about energy resources has attracted much research in the field of clean and sustainable energy sources. In this context, zero-emission fuels are required for energy production to reduce the usage of fossil fuel resources. Here, we present the synthesis of Pd-Ag-decorated reduced graphene oxide (rGO) nanostructures using a green chemical approach with stevia extract for hydrogen production and antibacterial studies under light irradiation. Moreover, bimetallic nanostructures are potentially lime lighted due to their synergetic effect in both scientific and technical aspects. Structural characteristics such as crystal structure and morphological features of the synthesized nanostructures were analyzed using X-ray diffraction and transmission electron microscopy. Analysis of elemental composition and oxidation states was carried out by X-ray photoelectron spectroscopy. Optical characteristics of the biosynthesized nanostructures were obtained by UV-Vis absorption spectroscopy, and Fourier transform infrared spectroscopy was used to investigate possible functional groups that act as reducing and capping agents. The antimicrobial activity of the biosynthesized Pd-Ag-decorated rGO nanostructures was excellent, inactivating 96% of Escherichia coli cells during experiments over 150 min under visible light irradiation. Hence, these biosynthesized Pd-Ag-decorated rGO nanostructures can be utilized for alternative nanomaterial-based drug development in the future.

飞秒激光辐照氧化石墨烯的纳结构与电化学性能研究

飞秒激光辐照氧化石墨烯的纳结构与电化学性能研究

Angular study of laser induced fluorescence emission of hybrid media based on Stern-Volmer formalism

Here, the quenching process of Rhodamine B fluorophores coupled with Titanium dioxide (TiO2) nanoparticles (NPs) and Graphene oxide (GO) nano structures is empirically investigated during the laser induced fluorescence (LIF) events in various detection angles. According to Stern-Volmer formalism, the slope of Stern-Volmer graph is strongly dependent on the angular orientation of the detector, mainly because of the alteration in active volume. The corresponding spectral shift lucidly changes due to the anisotropy of the re-absorption events while the single and multiple scattering simultaneously take place, particularly at dense suspensions. The fluorescence Stokes shift of RdB molecules, as well as the effect of non-homogeneous population of the exited/unexcited molecules are taken into account as dominant factors during the measurements. However, the fluorescence trapping becomes more effective in dense suspension and larger detection angles.

Heat assisted facile synthesis of nanostructured polyaniline/reduced crumbled graphene oxide as a high-performance flexible electrode material for supercapacitors

Smart wearable electronic gadgets are getting popularity among the masses and their high demand leading the quest for high power/energy density flexible energy storage devices like supercapacitors and batteries. To address the need for high energy and high power in supercapacitors, we have prepared heat-assisted polyaniline (PANI)/reduced crumbled graphene oxide (rcGO) nanostructures as a high quality flexible electrode material through in-situ polymerization of aniline in the presence of crumbled graphene oxide (cGO). Spectroscopic results revealed the successful reduction of cGO by charge transfer from PANI chains during the heating process. The resulting PANI/rcGO nanocomposites have been used as electrode material, and cast into flexible electrodes to fabricate symmetrical supercapacitor device. The flexible PANI/rcGO electrodes have delivered a specific capacitance of 299 F g−1 at 0.5 A g-1 current density, whereas pure PANI given 248 F g-1 at the same rate. Further, PANI/rcGO nanocomposites exhibited long cyclic stability even after 2000 charge-discharge cycles. The excellent electrochemical performance of heat-assisted PANI/rcGO nanocomposites have been realized due to the lamination of rcGO by PANI chains and formation of high interfacial contact between rcGO and polymer chains.