Reduced Graphene Nanoribbons Research Articles

Particle size effect on graphene nanoribbons with iron oxide nanoparticles

The particle size effect on nanocomposites made of reduced graphene nanoribbons (GNRs) and iron oxide nanoparticles (IONPs) is studied. Three nanocomposites with different particle size were prepared by chemical reduction of IONPs formed by the co-precipitation method on graphene oxide nanoribbons. Several experimental techniques such as transmission electron microscopy, selected area electron diffraction and X-ray diffraction determined the particle size distribution and crystalline phases present in the samples. The specific surface area (SSA) of the nanocomposites was measured and discussed with the mean size of the IONPs. Depending on the mean size and surface distribution of the IONPs, samples with high SSA can be achieved. Magnetic measurements indicated that the particle size affects the magnetic properties of the nanocomposites. These results were discussed considering the effect of particle size, defects, amount of particles and interaction between the IONPs and GNRs surface. The potential application of the samples as supercapacitors was evaluated by calculating their specific capacitance from cyclic voltammetry measurements. The results showed that the specific capacitance increases with the SSA. This work confirms that the size of the IONPs significantly affects the properties of the nanocomposites, specifically the SSA, which is of great interest for various applications.

Construction of a self–reporting molecularly–imprinted electrochemical sensor based on CuHCF modified by rGNR–rGO for the detection of zearalenone

A self–reporting molecularly–imprinted electrochemical sensor is prepared for the detection of Zearalenone (ZEA). Firstly, the reduced graphene nanoribbons and reduced graphene oxide (rGNR–rGO) were simultaneously modified onto a glassy carbon electrode (GCE) to improve the sensor's sensitivity. After electrodepositing copper nanoparticles onto the rGNR–rGO/GCE, cyclic voltammetry scanning was performed in potassium ferrocyanide solution, and copper hexacyanoferrate (CuHCF) was deposited onto rGNR–rGO/GCE to further improve the sensor's sensitivity while giving it self–reporting capability. Then, molecularly–imprinted polymer films were prepared on the CuHCF/rGNR–rGO/GCE to ensure the selectivity of the sensor. It is found that the linear range of ZEA detection by the constructed sensor is 0.25–500 ng·mL −1, with a detection limit of 0.09 ng·mL −1. This sensor shows the merits of good selectivity, high sensitivity and accurate detection, providing a great possibility for the precise detection of low concentration ZEA in food.

Enhanced charge mediator properties of photocatalysts with reduced graphene nanoribbons for photocatalytic acceleration of hydrogen production in aqueous media

In this study, a hybrid photocatalyst with titanium oxide using reduced graphene nanoribbons (rGNR) was fabricated.

Construction of AuNPs/reduced graphene nanoribbons co-modified molecularly imprinted electrochemical sensor for the detection of zearalenone

In this work, a highly sensitive and selective molecularly imprinted electrochemical sensor is exploited to detect zearalenone (ZEA) by the synergistic effect of reduced graphene nanoribbons (rGNRs) and gold nanoparticles (AuNPs). The oxidized GNRs are firstly produced by an improved Hummers’ oxidation method, and then reduced and modified together with AuNPs onto a glassy carbon electrode by electrodeposition technique to realize collaborative amplification of electrochemical signal. The molecularly imprinted polymer film with specific recognition sites can be generated on the modified electrode by electropolymerization. The effect of experimental conditions is systematically investigated to obtain the best detection performance. It is found that the constructed sensor shows a wide linear range of 1–500 ng·mL−1 for ZEA with a detection limit as low as 0.34 ng·mL−1. Obviously, our constructed molecularly imprinted electrochemical sensor shows great potential in the application of precisely detecting ZEA in food.

Minimization of crosstalk noise and delay using reduced graphene nano ribbon (GNR) interconnect

In this paper, we proposed a side-contact reduced graphene nano-ribbon (SC-RGNR) interconnect model to reduce crosstalk noise and delay for next generation high performance integrated circuit (IC) design. The SC-RGNR interconnect structure is designed with latest 11 nm ITRS (International Technological Road Map for Semiconductor) technology node. A comparative crosstalk noise, delay and power consumption analysis has been performed with side-contact graphene nano-ribbon (SC-GNR) interconnect model. The SC-RGNR and SC-GNR interconnect both model parameters are applied in standard (STD) bus and staggered (STAGG) bus model with different interconnect lengths (10 μm–500 μm) and four standard mean free paths (MFP) (i.e., 300 nm, 419 nm, 1000 nm and 1200 nm) values. Five different switching conditions (i.e., SP1 to SP5) are applied on tri-interconnect driver-load circuit to check the performance of SC-RGNR and SC-GNR interconnect in-terms of crosstalk noise and delay. In our analysis, it is shown that, the higher MFP based SC-RGNR interconnect shows less dynamic delay compared with SC-GNR interconnect for both STD and STAGG interconnect model with worst-case switching condition (SP5) and best-case switching condition (SP2). For STD interconnect model with worst-case switching condition (SP5) the dynamic delay of SC-RGNR interconnect is ∼1.33–2.62 × lesser than SC-GNR interconnect. Similarly, for STAGG model with worst-case switching condition (SP5) the dynamic delay of SC-RGNR interconnect is ∼1.26–2.16 × lesser than SC-GNR interconnect. Although, the STAGG interconnect model performs ∼1.5–2 × faster than STD interconnect model in terms of delay. In our analysis, it is also observed that, the output noise peak is ∼2.91–17.5 × less in SC-RGNR compared with SC-GNR at 500 μm interconnect length and higher MFP. Our analysis also shows that, the switching power consumption in SC-RGNR is ∼1.66–2.2 × less than SC-GNR for both STD and STAGG model for both best and worst-case switching condition (SP2 and SP5).

Chemically derived graphene nanoribbons from carbon nanotubes for supercapacitor application

Present paper reports reduced Graphene nano ribbons (GNR) synthesized via longitudinal splitting of carbon nano tubes (CNTs) using simple oxidation reduction approach. GNRs, thus obtained, has less defects and distortion than the earlier reported method of GNRs synthesis. GNRs properties are confirmed by various spectroscopic analysis . The crystallographic features of the GNRs have been explored via XRD analysis. In order to identify the morphological features of the GNRs, scanning electron microscopy (SEM) is performed. To have a better understanding of GNRs at atomic level, optical analysis is done via UV-vis absorption technique. UV-vis absorption results are further verified by FTIR spectroscopic analysis. The cyclic voltammetric (CV) analysis is also carried out to further explore the suitability of GNRs as potential supercapacitor (SC) electrode material. A brief discussion on the possible use of material in various fields and possible future scope is also presented.

Paper-based electrochemical sensors with reduced graphene nanoribbons for simultaneous detection of sulfamethoxazole and trimethoprim in water samples

Failure to control the levels of emerging pollutants in water supply can affect the quality of human life, and this may be mitigated with a low-cost, real-time monitoring system. Herein, we describe a paper-based fully printed electrochemical sensor with reduced graphene nanoribbons (rGNR) capable of detecting sulfamethoxazole (SMX) and trimethoprim (TMP) antibiotics simultaneously in real water samples. The electrodes were printed on parchment paper, which is environmentally friendly and has an efficient printing capacity. Deposition of rGNRs in the matrix was confirmed with Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoemission spectroscopy (XPS). Optimized sensing performance was obtained using an electrochemical treatment of the electrodes at neutral pH. The paper-based sensor displayed a linear response from 1 μmol l−1 to 10 μmol l−1 for both antibiotics, with detection limits of 0.09 μmol l−1 and 0.04 μmol l−1 for SMX and TMP, respectively. The sensor was reproducible, with an RSD below 5%, and selective for the antibiotics including in real samples, in a demonstration of its potential for real-time monitoring of water supply systems.

Treated Screen Printed Electrodes Based on Electrochemically Reduced Graphene Nanoribbons for the Sensitive Voltammetric Determination of Dopamine in the Presence of Uric Acid

AbstractIn this research, the graphene oxide nanoribbons (GONRs) were substantially synthesized by the oxidative longitudinal unzipping of the multi‐walled carbon nanotubes (MWCNTs). Then, a direct electrochemical technique was employed for reducing GONRs adsorbed on the screen printed carbon electrode (SPCE). Electrochemical reduction effectively eliminated the oxygen‐containing groups in the GONRs and produced the electrochemically reduced graphene nanoribbons (ERGNRs). Field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) were employed to characterize the materials. The modified SPCE with ERGNRs (ERGNRs/SPCE) displayed acceptable electrocatalytic characteristics towards the oxidation of dopamine (DA) and uric acid (UA) and applied to the simultaneous determination of these two analytes. ERGNRs/SPCE has a peak potential difference of 245 mV between DA and UA. The anodic peak currents of DA and UA were linear within the concentration ranges between 0.5 and 300.0 μM and 1.0 to 400.0 μM in phosphate buffer (pH=7.0) respectively. The detection limit of the technique for DA is 0.15 μM (S/N=3) and for UA is 0.3 μM (S/N=3). The proposed approach has been applied to the determination of DA and UA in real samples and generated acceptable outputs.

Dependence of reduction degree on electromagnetic absorption of graphene nanoribbon unzipped from carbon nanotube

Carbon materials are very promising for electromagnetic wave absorption application due to their light weight and low cost, where the reflection loss is used to evaluate the absorption efficiency. However, the reflection loss of carbon materials (carbon foam, graphene, and carbon nanotube) without loading magnetic particles is not as high as expected. Here, we propose to unzip carbon nanotubes into graphene oxide nanoribbons (GONRs), followed by controllable reduction treatment using hydrazine hydrate, and the reduced GONRs were finalized (called as r-GONRs). The r-GONRs exhibit obvious dielectric relaxation behaviors compared to GONRs, and the dielectric loss is improved by increasing the reduction degree. The optimized r-GONRs show ultrahigh electromagnetic absorption, up to −65.09 dB at a thickness of 2 mm, which is more advantageous than the reported values of other carbon materials. The efficient absorption bandwidth (reflection loss ≤−10 dB) reaches 7.06 GHz. These are attributed to the large dielectric loss of the unique graphene nanoribbon. Our controllable reduced graphene nanoribbon is promising in the application of radar wave absorption and electromagnetic shielding.

Enhanced magnetic properties of cobalt-doped graphene nanoribbons

We have studied structural and magnetic properties of reduced graphene nanoribbons (GNRs) and cobalt (Co)-doped GNRs. The effect of Co was also investigated on the magnetic properties of pristine GNRs, which play vital role in contribution of calculated magnetic moment. Herein, we have synthesized the pristine GNRs and Co-doped GNRs via a simple chemical refluxing process. The analysis of synthesised materials were carried out using different techniques such as Field emission scanning electron microscopy (FESEM) with EDAX analysis and X-ray diffraction pattern were confirmed the doping of Co into the GNRs. Moreover, from morphological analysis (FESEM), impurity or dopant (Co) shows as adsorbed at the surface of GNRs. Raman analysis has proved that the incorporation of Co into graphitic structure creates more defective sites. The results obtained from VSM analysis is clearly revealed that enhanced saturation magnetization (Ms) from ~13.08 × 10−2 emu/g to ~37.35 × 10−2 emu/g, due to the presence of unbalanced electron spins in Co which may be responsible for higher saturation magnetization in case of Co-doped GNRs as comparison of pristine GNRs. The obtained interesting magnetic properties of Co-doped GNRs create much attention towards various applications including spintronics devices and some related fields.

Highly sensitive determination of non-steroidal anti-inflammatory drug nimesulide using electrochemically reduced graphene oxide nanoribbons

Preparation of an electrochemically reduced graphene nanoribbon (ER-GONR) film modified screen-printed carbon electrode for the highly sensitive determination of nimesulide.

Preparation of Reduced-Graphene Nanoribbons via One-Step Solvothermal Process.

Carbon nanotubes were unzipped to become reduced-graphene nanoribbons via one-step solvothermal process in a Teflon-lined autoclave. The samples were characterized by X-ray diffraction, thermo-gravimetric analysis and transmission electrical microscopy, respectively. Results showed that the solvothermal reaction temperature played an important role in the structure of the samples. When it was 75 °C, carbon nanotubes were completely cutted into graphene oxide nanoribbons. Moreover, when it was 155 °C, they were become reduced-graphene nanoribbons. Furthermore, the as-prepared reduced-graphene nanoribbons could improve mechanical strength of the phenolic resin/hollow glass beads foamed composites. When the reduced-graphene nanoribbons loading was 0.4 wt%, the tensile and compressive strength of the composites were increased by 19.7% and 21.3%, respectively.

Graphene nanoribbon-based electrochemical sensors on screen-printed platforms

In this work, oxidized graphene nanoribbons (GNRox) and reduced graphene nanoribbons (GNRred) were explored for the construction of disposable electrochemical sensors on screen-printed platforms for the sensing of ascorbic acid (AA), levodopa (LD) and uric acid (UA).GNRred demonstrated improved electroanalytical performance in comparison not only with the carbon screen printed electrodes (CSPEs), but also with other related carbon nanomaterials such as multi-walled carbon nanotubes (MWCNTs) and GNRox. MWCNTs served as the carbon source for GNRox which was further reduced to form GNRred.The excellent electrocatalysis exhibited by this carbon nanomaterial toward AA, LD and UA allowed a fast (100s), selective (at +0.08, +0.27 and +0.39V, respectively), and accurate determination (with recoveries between 97 to 101%) of these analytes in urine samples.Excellent intra-electrode repeatability (RSD <5%, n=10), inter-electrode reproducibility (RSD < 13%, n=5 electrodes) and stability of the sensor (the electrode maintained 93±3% of its signal after 15 days) were also demonstrated, becoming this electrochemical sensor a valuable tool for clinical routine uric acid assessment.Tailored graphene nanoribbons on screen-printed platforms become a new generation of disposable graphene-based electrochemical sensors for POC testing applications.

Electrochemically reduced graphene nanoribbons: Interference from inherent electrochemistry of the material in DPV studies

Graphene nanoribbons (GNRs) are attracting the interest of scientific community due to the outstanding versatility of their properties and applications. One of the most successful routes for the production of GNRs is the oxidative unzipping of carbon nanotubes followed by electrochemical reduction of oxygen functionalities. Electrochemically reduced graphene nanoribbons may present a reduced anodic potential window due to the intrinsic reversible chemistry of oxygen functionalities. Here we show that the oxidation signal obtained for caffeine on GNRs is strongly influenced by the inherent background signal of the reduced graphene nanoribbon material. Our findings provide important insight into the origin of the electrochemical signal obtained in the anodic region when using electrochemically reduced graphene nanoribbons as platform for sensing and biosensing. This insight bears high importance for future use of electrochemically reduced graphene nanoribbons in electroanalysis.

Enzymatic Degradation of Oxidized and Reduced Graphene Nanoribbons by Lignin Peroxidase.

The expanding use of graphene for various industrial and biomedical applications requires efficient remediation strategies during their disposal into waste streams. Additionally, the interactions of graphene with the biota need thorough evaluation. In this study, we investigated the interactions of oxidized and reduced graphene oxide nanoribbons (GONRs and rGONRs) with lignin peroxidase (LiP), a ligninolytic enzyme released from white rot fungus. GONRs and rGONRs were treated with LiP in the presence and absence of veratryl alcohol (VA; an electron transfer mediator and secondary metabolite of white rot fungi). Transmission electron microscopy showed the formation of large defects (holes) in the graphene sheet, which increased in diameter with increased degradation time. Raman spectroscopic analysis indicated that, within 96 hours, in the presence of hydrogen peroxide and VA, the GONRs and rGONRs were completely and partially degraded by LiP, respectively. Comparisons between groups with or without VA showed that degradation of GONRs was accelerated in the presence of VA. These results indicated that LiP could efficiently degrade GONRs and rGONRs in the presence of VA, suggesting that VA may be an essential factor needed to degrade rGONRs via LiP treatment. Thus, the wide presence of white rot fungi, and thereby LiP, in nature, could lead to efficient degradation of graphene present in the environment. Additionally, LiP, which has a higher theoretical redox potential compared to horseradish peroxidases and myeloperoxidases, could be a better candidate for the environmental remediation of graphene.

ChemInform Abstract: Graphene Oxide Nanoribbons (GNO), Reduced Graphene Nanoribbons (GNR), and Multi‐layers of Oxidized Graphene Functionalized with Ionic Liquids (GO‐IL) for Assembly of Miniaturized Electrochemical Devices

AbstractReview: 171 refs.

One-step hybridization of graphene nanoribbons with carbon nanotubes and its strong-yet-ductile thermoplastic polyurethane composites

A hybrid of reduced graphene nanoribbon (GNR)–carbon nanotube (CNT) (i.e. R-GNR/CNT hybrid) with unique three-dimensional (3D) nanostructures has been prepared via a facile unzipping and reducing method. Interlocked structures are formed within the nanohybrids where one-dimensional (1D) CNTs act as bridges connecting individual two-dimensional (2D) GNRs, which not only prevent the aggregation of GNRs but also promote the formation of 3D hybrid with cross-linked nanostructure. Thermoplastic polyurethane (TPU) composites with different R-GNR/CNT hybrid loadings have been fabricated via solution casting. With the addition of small amount of R-GNR/CNT hybrids, apart from the largely improved tensile strength and Young's modulus, the toughness of the TPU composites is surprisingly enhanced. Here, the toughening mechanisms are also discussed. Furthermore, the electrical conductivities of the TPU composites are also significantly enhanced in the presence of this 3D R-GNR/CNT nanohybrid due to the formation of conductive pathways within the matrix.

Graphene Nanoribbons as an Advanced Precursor for Making Carbon Fiber

Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers' performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young's modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning.

Graphene oxide nanoribbons (GNO), reduced graphene nanoribbons (GNR), and multi-layers of oxidized graphene functionalized with ionic liquids (GO–IL) for assembly of miniaturized electrochemical devices

In this critical review, new nanomaterials based on graphene (GN) are described, especially those used for the assembly of miniaturized electrochemical transducers. In particular, the physicochemical properties and mechanical features of few layers of graphene (FLGs) are described, as is their use for assembly of chemically modified sensors, biosensors, and immunosensors. The FLGs described here were functionalized by chemical treatment in solution, resulting in oxidized and/or reduced surfaces, edges, and sides. The presence of oxygenated functionality strongly affects the electrocatalysis and the electron-transfer properties of several molecular targets, not only in the solid phase (e.g. in field-effect transistors, FETs) but also in liquid matrices (chemically modified electrodes and biosensors). In addition, "green chemistry" reagents, for example ionic liquids (ILs) can be used for exfoliation and intercalation of graphene planes, to obtain stable and homogeneous nanodispersions. The assembled sensors, biosensors, and immunosensors are extremely useful for electrochemical detection of several electro-active targets of importance in food analysis, environmental monitoring, and clinical diagnosis. A detailed description of each analytical application has been given in this critical review and brief remarks on the emerging disciplines of nanomedicine and nanofoods are also discussed.

Reconstructed Ribbon Edges in Thermally Reduced Graphene Nanoribbons

Graphene oxide nanoribbons (GONRs) with a high aspect ratio and high gravimetric density of their edges relative to those of graphene flakes are promising platforms for graphene-based devices. Since the edge chemistry of GONRs determines their final electronic and transport properties, it is important to understand the interactions of oxygen with the edges of the ribbons. Although oxidative unzipping of carbon nanotubes has been studied by Dai’s(1) and Tour’s(2) groups for GONR production, the role of oxygen concentration, the nature of edge oxygen groups, and their effect on the ribbon-edge geometry is still not well understood. We have therefore studied thermal annealing of GONRs, obtained by unzipping few-walled or multi-walled carbon nanotubes, focusing on the reduction process. For this purpose, in situ infrared absorption spectroscopy is used to monitor the edge reconstruction during the thermal reduction process. The ribbon edges of reduced graphene nanoribbons (rGNRs), initially functionalized with carboxyls, are found to convert to edge carbonyls during annealing at high temperatures (∼850 °C). The formation of these highly stable carbonyl species therefore leads to edge reconstruction of rGNRs after high-temperature anneals. The concentrations of initial hydroxyl, edge carbonyl, and carboxyl are found to be key factors that determine the resulting oxygen concentration in rGNRs after annealing. Although the initial concentration of these oxygen groups introduced during unzipping is associated with the concentration of oxidant (KMnO4 or H3PO4), the resulting amount of total oxygen in rGNRs upon thermal reduction is found to be independent of the wall thickness of the starting carbon nanotubes (i.e., number of original unzipped layers of GONRs).