Reduced Graphene Oxide Nanoribbons Research Articles

Nickel-Induced Reduced Graphene Oxide Nanoribbon Formation on Highly Ordered Pyrolytic Graphite for Electronic and Magnetic Applications.

The development of nanoribbon-like structures is an effective strategy to harness the potential benefits of graphenic materials due to their excellent electrical properties, advantageous edge sites, rapid electron transport, and large specific area. Herein, parallel and connected magnetic nanostructured nanoribbons are obtained through the synthesis of reduced graphene oxide (rGO) using NiCl2 as a precursor with potential applications in nascent electronic and magnetic devices. Several analytical techniques have been used for the thorough characterization of the modified surfaces. Atomic force microscopy (AFM) shows the characteristic topographical features of the nanoribbons. While X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy provided information on the chemical state of Ni and graphene-like structures, magnetic force microscopy (MFM) and scanning Kelvin probe microscopy (SKPFM) confirmed the preferential concentration of Ni onto rGO nanoribbons. These results indicate that the synthesized material shows 1D ordering of nickel nanoparticles (NiNPs)-decorating tiny rGO flakes into thin threads and the subsequent 2D arrangement of the latter into parallel ribbons following the topography of the HOPG basal plane.

Nitrogen‐Doped Graphene Oxide Nanoribbon Supported Cobalt Oxide Nanoparticles as High‐Performance Bifunctional Catalysts for Zinc–Air Battery

Developing high‐performance, high‐stability, and low‐cost nonprecious metal catalysts to enhance the performance of zinc–air batteries (ZABs) holds significant importance. A bifunctional catalyst consisting of cobalt oxide (CoO) nanocrystals on nitrogen‐doped reduced graphene oxide nanoribbons (N‐rGONR) as a novel substrate is successfully synthesized in this work. This synthesized bifunctional catalyst exhibits mesoporous structure, and remarkable synergistic effects between CoO nanocrystals and N‐rGONR, demonstrating excellent activity and durability in both oxygen reduction reactions and oxygen evolution reactions. Notably, the resulting aqueous electrolyte ZABs show a high discharge peak power density of 196 mW cm−2, a high specific capacity of 615.9 mAh g−1, and long‐time stability for 648 h. Furthermore, the assembly of 1D and 2D flexible solid‐state ZABs fabricated using this bifunctional catalyst exhibits stable electrochemical performance, even under severe deformation. These results underscore the considerable promise of implementing the CoO@N‐rGONR catalyst structure in next‐generation advanced energy storage and conversion devices.

Strong Metal-Support Interaction – a Tool for Enhancing the Hydrogen Evolution Reaction Performance

Renewable and green energy transition and meeting ever-increasing energy demands are among modern society's most pressing challenges. Currently, the world's energy systems rely on fossil fuels, leading to significant environmental pollution, including anthropogenic CO2 emissions and subsequent climate changes. The concept of hydrogen economy was first proposed half a century ago as a way to overcome these challenges by using hydrogen as the primary energy carrier instead of fossils.1 However, hydrogen production remains one of the significant obstacles to realizing the hydrogen economy, as steam reforming of methane derived from natural gas is still the dominant method of industrial-scale production, contributing significantly to the undesired emissions. Water electrolysis powered by renewables such as wind and sun energy is a sustainable way to produce high-purity hydrogen. In electrolyzers, hydrogen is obtained at the cathode side through the electrochemical hydrogen evolution reaction (HER), while the oxygen evolution reaction (OER) occurs at the anode. The HER is one of the most intensely studied electrochemical processes as it is of paramount importance for both fundamental and applicable aspects of electrocatalysis and physical chemistry in general. Traditionally, Pt has been known as the best monometallic HER catalyst due to its close-to-optimal interaction with adsorbed hydrogen atoms, which are reaction intermediates.2 However, due to its scarcity and high price, significant research efforts are being invested in designing alternative Pt-free electrocatalysts for (not only) HER. While promising results have been reported with different abundant materials such as sulfides, nitrides, carbides, and phosphides, their applicability is still challenged by rather inferior activity with respect to Pt and rapid deactivation, especially in corrosive acidic media. Currently, state-of-the-art HER catalysts are based on Pt nanoparticles dispersed over high-surface-area carbon supports (Pt/C). The main downside of such composites is the weak interaction between carbon and Pt particles, which means that support cannot affect the intrinsic activity of Pt sites. Moreover, this weak interaction results in the degradation of Pt/C due to particle detachment, agglomeration, or coalescence during HER. Upgrading the overall performance of Pt/C may be achieved by employing alternative supports able to trigger strong metal-support interaction (SMSI). SMSI can alter the electronic structure of the metallic active sites and increase their activity, while also it can lead to the stronger anchoring of nanoparticles with the support, improving stability. Different materials, such as pre-functionalized carbons, carbides, and metal oxides, have been reported to be able to provide SMSI.In this work, we investigated HER on a carbon-ceramic catalyst composed of Pt nanoparticles supported on titanium oxynitride (TiONx) embedded on reduced graphene oxide nanoribbons (Pt/TiONx).3 TiONx was obtained by incorporating nitrogen into TiO2 and provides the main merits of carbon supports, such as electrical conductivity and high surface area, combined with the ability to trigger SMSI. The screening of the electrocatalytic performance of the Pt/TiONx composite for HER revealed enhancement with respect to the Pt/C benchmark, which we ascribe to the effect of the TiONx substrate via SMSI. To confirm this, XPS was performed to compare the electronic states of Pt in Pt/TiONx and Pt/C catalysts, which revealed the ability of TiONx to trigger SMSI. DFT calculation provided additional confirmation of SMSI between the TiONx support and Pt nanoparticles and its impact on both HER activity and stability enhancement. The results presented in this work open up a perspective of using TiONx as an alternative support able to improve the catalytic performance of various active sites for different electrochemical reactions. References (1) Bockris, J. O. M. The Hydrogen Economy: Its History. Int J Hydrogen Energy 2013, 38 (6), 2579–2588. https://doi.org/10.1016/j.ijhydene.2012.12.026.(2) Hansen, J. N.; Prats, H.; Toudahl, K. K.; Mørch Secher, N.; Chan, K.; Kibsgaard, J.; Chorkendorff, I. Is There Anything Better than Pt for HER? ACS Energy Lett 2021, 1175–1180. https://doi.org/10.1021/acsenergylett.1c00246.(3) Smiljanić, M.; Panić, S.; Bele, M.; Ruiz-Zepeda, F.; Pavko, L.; Gašparič, L.; Kokalj, A.; Gaberšček, M.; Hodnik, N. Improving the HER Activity and Stability of Pt Nanoparticles by Titanium Oxynitride Support. ACS Catal 2022, 12 (20), 13021–13033. https://doi.org/10.1021/acscatal.2c03214. Figure 1

Integration of SrFeO3-δ with reduced graphene oxide nanoribbon for symmetric/asymmetric capacitive charge storage

Oxygen-deficient perovskite oxides are attractive electrode materials due to their tendency to store charge through anion intercalation mechanism. Herein, SrFeO3-δ (SFO) is synthesized and studied for supercapacitor application. In order to have better stability and electrolytic accessibility, SFO is immoblized over holey-reduced graphene oxide nanoribbons (rGONR) in different ratios by varying rGONR content viz. 20, 40, 60 and 80 wt%. The hybrid material comprising 60 wt% rGONR (SFO/rGONR60) exhibits maximum specific capacitance (Csp) of 1143.7 F g−1 at 5 A g−1 with good cycling stability of ∼90.3% capacitance retention over 5000 galvanic charge-discharge (GCD) cycles at 20 A g−1. The high electrochemical performance of SFO/rGONR60 hybrid is attributed to its good electronic conductivity, improved ionic diffusion and the presence of enormous active sites. Asymmetric cell (K-doped δ-MnO2||SFO/rGONR60), on operating up to 1.5 V, can deliver high energy (E) and power (P) densities of 76 Wh kg−1 and 1463 W kg−1, respectively, which is greater than that of symmetric (SFO/rGONR60||SFO/rGONR60) cell. This research helps in understanding the relationship between oxygen-deficient perovskite oxide and rGONR in charge storage and cell performance.

Ni and Fe mixed oxide anchored on CNTs, GONRs, and Ti3C2 Mxene as efficient nanocatalysts for direct power generation from methanol electro-oxidation

In the field of heterogeneous catalysis, the selection of appropriate support is an effective strategy due to metal loading reduction and enhancing electron transfer kinetic. In this work, the performance of carbon nanotubes (CNTs), reduced graphene oxide nanoribbons (rGONRs), and titanium carbide nanosheets (Ti3C2 Mxene) as support was investigated on the catalytic performance of NiFe2O4 spinel nanoparticles. The samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, BET surface area analysis, field emission scanning, and transmission electron microscopy. The electrochemical properties of samples as fuel cell catalysts were compared using electrochemical techniques. The electrocatalytic activity of samples in methanol oxidation reaction (MOR) was obtained to be: NiFe2O4/Ti3C2> NiFe2O4/rGONRs > NiFe2O4/CNTs > NiFe2O4. The results approve that the Ti3C2 Mxene promotes the catalytic performance of NiFe2O4 and enhances the methanol oxidation kinetics via conductive pathway creation. Therefore, Ti3C2 can lead to great opportunities as an efficient catalyst support for alcohol fuel cells in the future.

Cobalt ferrite nanoparticles anchored on reduced graphene oxide nanoribbons (0D/1D CoFe2O4/rGONRs) as an efficient catalyst for hydrogen generation via NaBH4 hydrolysis

For better performance of nanoparticles as the heterogeneous catalyst, various materials with a large surface area have been introduced as the substrate. Herein, CoFe2O4 nanoparticles were anchored on carbon nanotubes (CoFe2O4/CNTs) and graphene nanoribbons (CoFe2O4/GONRs) to investigate the influence of substrate in the catalytic performance. These nanocomposites were evaluated in a NaBH4 hydrolysis reaction to produce hydrogen. The results showed that the highest hydrogen volume occurs in the presence of CoFe2O4/GONRs nanocatalyst. Abundant oxygen-based functional groups at the edges of GONRs offered excellent sites for CoFe2O4 nanoparticles and improved catalytic performance. Under optimum conditions (2.0 wt% of NaBH4, 15 mg of catalyst, 2.0 wt% of NaOH), the hydrogen generation rate was found to be 3.7 L g-1min−1 at 35 °C. The activation energy was calculated using the Arrhenius method, equivalent to 31.4 kJ mol−1. Therefore, CoFe2O4/GONRs catalyst can be a novel and efficient candidate for hydrogen production as a clean fuel.

Improving the HER Activity and Stability of Pt Nanoparticles by Titanium Oxynitride Support.

Water electrolysis powered by renewables is regarded as the feasible route for the production of hydrogen, obtained at the cathode side through electrochemical hydrogen evolution reaction (HER). Herein, we present a rational strategy to improve the overall HER catalytic performance of Pt, which is known as the best monometallic catalyst for this reaction, by supporting it on a conductive titanium oxynitride (TiONx) dispersed over reduced graphene oxide nanoribbons. Characterization of the Pt/TiONx composite revealed the presence of small Pt particles with diameters between 2 and 3 nm, which are well dispersed over the TiONx support. The Pt/TiONx nanocomposite exhibited improved HER activity and stability with respect to the Pt/C benchmark in an acid electrolyte, which was ascribed to the strong metal–support interaction (SMSI) triggered between the TiONx support and grafted Pt nanoparticles. SMSI between TiONx and Pt was evidenced by X-ray photoelectron spectroscopy (XPS) through a shift of the binding energies of the characteristic Pt 4f photoelectron lines with respect to Pt/C. Density functional theory (DFT) calculations confirmed the strong interaction between Pt nanoparticles and the TiONx support. This strong interaction improves the stability of Pt nanoparticles and weakens the binding of chemisorbed H atoms thereon. Both of these effects may result in enhanced HER activity.

Adsorption chemistry of co-doped graphene nanoribbon and its derivatives towards carbon based gases for gas sensing applications: Quantum DFT investigation

Sensing of the toxic gases plays a vital role in the human life to improve their health aspects and the quality of life. Using the first-principles calculations combined with density functional theory (DFT), the authors in this research work have explored the adsorption energy and electronic features of co-doped armchair graphene nanoribbon (ArGNR) and its derivatives, such as the co-doped armchair graphene oxide nanoribbon (ArGONR) and co-doped armchair reduced graphene oxide nanoribbon (ArRGONR) with boron and phosphorus (BP) atoms. A comparative study of detection of toxic carbon based gases (CO, CO2, CH4) on co-doped graphene nanoribbon (BP-ArGNR), and its derivatives such as BP-ArGONR (addition of more oxygen atoms in pristine ArGNR) and BP-ArRGONR (addition of less oxygen atoms in pristine ArGNR) has been performed. To evaluate the sensing of carbon based gases, their adsorption energies, binding distances, charge transfer, band structures and density of states have been studied for different variants. Before modification, adsorption energies for BP-ArGNR have been found to be smaller than the BP-ArGONR for CO, CO2 and CH4 molecules, thereby showing physisorption mechanism. Our computational results also revealed that after modification with oxygen atoms, BP-ArGONR shows relatively more negative value of adsorption energy in comparison to the pristine ArGNR (PR-ArGNR) for CO, CO2 and CH4 molecules, thereby showing chemisorption phenomenon. Band structure analysis predicts large band gap variations for BP-ArGONR as compared to PR-ArGNR. Thus, the authors concluded that after modification of graphene surface, enormous changes are observed in adsorption energies and band gap for BP-ArGONR towards all carbon based gases under study and hence significantly enhance the sensing performance of pristine graphene.

Enhancing Iridium Nanoparticles’ Oxygen Evolution Reaction Activity and Stability by Adjusting the Coverage of Titanium Oxynitride Flakes on Reduced Graphene Oxide Nanoribbons’ Support

AbstractHydrogen production from solar energy is currently considered the best alternative to fossil fuels. Thus, materials enabling efficient and sustainable energy conversion and storage need to be developed. Iridium is still the only material used in proton exchange membrane electrolyzers that efficiently catalyze hydrogen evolution counter‐reaction, namely, the oxygen evolution reaction (OER) for electrochemical water splitting in acidic media. With no practical alternatives that can sustain the harsh reaction conditions, new approaches need to be developed to increase the utilization of this scarce metal. Hereby, a carbon–ceramic nanocomposite material is investigated, where Ir nanoparticles and nanoflakes of titanium oxynitride (TiONx) are deposited on the surface of reduced graphene oxide nanoribbons (rGONRs). OER performance is shown to be dependent on the mutual distribution of the Ir–TiONx–rGONR phases and in the best case leads up to 30 times higher activity relative to the commercial IrO2 benchmark. Adjusting the domains of different chemical nature within the same hybrid nanocomposite material through the formation of heterojunctions is shown to boost OER performance. This work demonstrates how fine‐tuning of morphology, composition, and particle distribution of the carbon–ceramic catalytic material can introduce a strong synergistic effect on OER activity and stability of iridium.

Reduced Graphene Oxide Nanoribbons for the Magnetic Solid-Phase Extraction (MSPE) of Bisphenol Endocrine Disruptors in Carbonated Beverages with Determination by High-Performance Liquid Chromatography with Ultraviolet Detection (HPLC-UV)

A novel magnetic reduced graphene oxide nanoribbons (Fe3O4 @RGONRs) composite was prepared and applied as an adsorbent of magnetic solid-phase extraction (MSPE) for the determination of four bisphenol endocrine disrupters in three carbonated beverages coupled with high-performance liquid chromatography (HPLC). The prepared Fe3O4@RGONRs composite was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometry, nitrogen adsorption-desorption isotherms and zeta potential analysis. Fe3O4@RGONRs composite possessed an abundant π-electron system and interacted with the analytes by π-π stacking, hydrophobic interactions, and hydrogen bond. The MSPE parameters, including the mass of adsorbent, sample solution pH, extraction time, ionic strength, desorption solvent and desorption time, were evaluated. Under the optimal conditions, the proposed Fe3O4@RGONRs-based MSPE method exhibited good linearity with determination coefficients (R2) between 0.9994 and 1000 from 1.6 to 1000 µg L−1, low limits of detection from 0.33 to 0.87 µg L−1, and suitable accuracy with spiked recoveries from 81.88% to 115.73%. The excellent analytical performance, along with suitable batch-to-batch reproducibility and reusability, suggest potential applications in the field of sample pretreatment.

Mesoporous Hydrated Graphene Nanoribbon Electrodes for Efficient Supercapacitors: Effect of Nanoribbon Dispersion on Pore Structure

Abstract Graphene nanoribbons (GNRs), which are narrow and elongated strips of graphene, enable the formation of a more interconnected pore structure than two-dimensional graphenes. In this work, hydrated GNR sheets with different internal pore structures were prepared from chemically reduced graphene oxide nanoribbons with different reduction durations. The electrochemical properties of the hydrated GNR electrodes were determined by the mesoporous structure including pore interconnectivity, which depends on the reduction time. The disorderly-structured GNR electrode showed an excellent capacitance retention (71% at 100 A/g compared to that at 0.1 A/g) and high energy and power densities of 5.54 Wh/kg and 313 kW/kg, respectively, which are superior to those of a reduced graphene oxide electrode fabricated under the same conditions. These results clearly indicate that a disordered internal structure with interconnected mesopores in hydrated GNR sheets effectively improves the energy and power densities and charge-discharge capability.

Ammonium decavanadate nanodots/reduced graphene oxide nanoribbon as “inorganic-organic” hybrid electrode for high potential aqueous symmetric supercapacitors

The issue of relatively low operating potential window in aqueous supercapacitors is usually conquered by fabrication of asymmetric devices. To achieve the same in symmetric cells, electrodes with high electrochemical activity and wide working potential are needed. Herein, we report a strategy to extend the operating potential by utilizing ammonium decavanadate-holey reduced graphene oxide nanoribbons (rGONR-ADV) as hybrid electrode for supercapacitors. Besides high charge storage, use of redox-active ADV in hybrid provides a large overpotential towards water reduction, enabling wide potential window. The nano hybrids are synthesized at three different temperatures (140 °C, 160 °C, 180 °C) where rGONR-ADV 160 shows unsurpassed performance (1186 F g−1 @ 1 A g−1) owing to the optimized synergistic effect, highly electroactive surface area and improved ionic diffusion. The rGONR-ADV 160‖rGONR-ADV 160 cell displays high specific capacitance (406 F g−1 @ 0.5 A g−1), decent cycling stability (83% after 5000 cycles) with high energy/power density (120.2 Wh kg−1 and 1624.14 W kg−1). Interestingly, this device works well up to 1.5 V in 1 M H2SO4 i.e. well beyond thermodynamic limit of water decomposition. Present study illustrates the performance of polyoxometalates based hybrid electrode for high potential aqueous supercapacitors and energy density for practical applications.

Electrochemiluminescent immunoassay for insulin by using a quencher pair consisting of CdS:Eu nanoclusters loaded with multiwalled carbon nanotubes on reduced graphene oxide nanoribbons and gold nanoparticle-loaded octahedral Cu2O

A sensitive electrochemiluminescence (ECL) immunosensor was constructed for detection of insulin. It is based on the quenching effect of octahedral cuprous oxide decorated with gold nanoparticles (Cu2O@Au NPs). A composite constructed from multiwalled carbon nanotubes/reduced graphene oxide nanoribbons provides a large specific surface that promotes electron transfer on the surface of electrodes. In parallel, CdS nanoclusters were loaded with europium(III) to get CdS:Eu NCs. The Eu(III) ions exert a large enhancement in ECL intensity of the CdS NCs. Cu2O is biocompatible and has a large specific surface. It was used as a quencher for the ECL immunosensor. If Au NPs are loaded onto Cu2O, the green fluorescence of the CdS NCs (with emission peaks at 525nm) is quenched. The Cu2O@Au NPs also can be employed as a label for the secondary antibodies (Ab2) to improve the sensitivity of the ECL immunosensor. The assay works in the 0.5pg·mL-1 to 50ng·mL-1 insulin concentration range and has a detection limit of 40 fg·mL-1. Graphical abstract The multiwalled carbon nanotubes/reduced graphene oxide nanoribbons (MWCNT/rGONRs-CdS: Eu NCs) was used as substrate. Europium(III) (Eu3+) improves the ECL intensity of CdS NCs. The synergistic effect between Cu2O and Au NPs decreases the electrochemiluminescence of MWCNTs/rGONRs-CdS:Eu NCs.

Fabrication of a Mo-Doped Strontium Cobaltite Perovskite Hybrid Supercapacitor Cell with High Energy Density and Excellent Cycling Life.

Enriched with oxygen vacancies, Mo-doped strontium cobaltite (SrCo0.9 Mo0.1 O3-δ , SCM) is synthesized as an oxygen anion-intercalated charge-storage material through the sol-gel method. The supplemented oxygen vacancies, good electrical conductivity, and high ion diffusion coefficient bestow the SCM electrode with excellent specific capacitance (1223.34 F g-1 ) and specific capacity (168.88 mAh g-1 ) at 1 A g-1 . The decisive constant (b-value) deduced for the charge storage mechanism (low scan-rate region) is nearly 0.8, indicating a highly capacitive process. In the high scan-rate region, however, the b-value is almost 0.5, and a linear pattern of charge (q) versus the inverse of the square root of the scan rate (v-1/2 ) is obtained. The results reveal O2- diffusion as the rate-limiting factor for charge storage. Furthermore, a hybrid cell (SCM∥LRGONR) is fabricated by using lacey, reduced graphene oxide nanoribbon (LRGONR) as the negative electrode, which exhibits a high energy density (74.8 Wh kg-1 at a power density of 734.5 W kg-1 ). With a charging time of only 20.7 s, the cell sustains a very high energy density (33 Wh kg-1 ) with a high power delivery rate (6600 W kg-1 ). The excellent cycling stability (165.1 % activated specific capacitance retention and 97.6 % of the maximum value attained) after 10 000 charge-discharge cycles, demonstrates SCM is a potential electrode material for supercapacitors.

Enhanced electrochemical performance of anion-intercalated lanthanum molybdenum oxide pseudocapacitor electrode

Metal oxides with oxygen vacancies can be exploited as a charge storage material for supercapacitor. This work demonstrates synthesis of lanthanum molybdenum oxide (La2Mo2O9, LMO) using different calcination temperatures (300, 400, 500, 600 and 700 °C). As prepared LMO500 illustrates its utilization as an anion intercalated material for supercapacitors. Among all LMOs, LMO500 electrode exhibits high gravimetric (727.18 F g−1 at 0.5 A g−1) and areal (290.87 mF cm−2 at 0.5 A g−1) capacitance. The superior electrochemical performance of LMO500 can be attributed to complete transformation of its mixed phases (i.e. oxides, hydroxides) to its pure oxides (β-La2Mo2O9). Due to existence of pure phase, devoid of secondary phases, LMO500 exhibits good electron kinetics which affords low charge transfer resistance. The asymmetric supercapacitor (LMO500‖LRGONR) employing lacey reduced graphene oxide nanoribbons (LRGONR) as negative electrode delivers high energy density of 52 Wh kg−1 at a power density of 474 W kg−1 which is more than twice of symmetric cell (LMO500‖LMO500). Other than high energy and power density, LMO500‖LRGONR cell shows 98.74% capacitance retention after 1000 GCD cycles at 1.0 A g−1, endorsing excellent cycle stability.

Microwave-assisted polyol preparation of reduced graphene oxide nanoribbons supported platinum as a highly active electrocatalyst for oxygen reduction reaction

Reduced graphene oxide nanoribbons (RGONRs) supported platinum catalysts were prepared by microwave-assisted polyol method, in which Pt nanoparticles were uniformly dispersed with a mean particle of 3.5 nm. During the synthesis, Pt ions were first attached to graphene oxide nanoribbons, then the encased metal ions and graphene oxide nanoribbons were simultaneously reduced by ethylene glycol. X-ray photoelectron spectra and X-ray diffraction indicate that the graphene oxide nanoribbons were partially reduced and the Pt nanoparticles were attached to the oxygen-containing groups on the surface of the support. Pt/RGONRs exhibits excellent activity for the oxygen reduction reaction, which is approximately 2 times better than commercial Pt/C with promising durability after 5000 cycles of accelerated durability tests. The enhancement of electrocatalytic activity and better durability may be explicated by the well dispersed Pt NPs on the RGONRs and the attachment of Pt ions with the oxygen-containing groups before the reduction. Reduced graphene oxide nanoribbons supported platinum catalyst (Pt/RGONRs) were prepared by microwave-assisted polyol method, which exhibited good electroactivity and promising stability toward the oxygen reduction reaction.

Reduced graphene oxide nanoribbon immobilized gold nanoparticle based electrochemical DNA biosensor for the detection of Mycobacterium tuberculosis.

Tuberculosis is one of the most dreadful diseases caused by Mycobacterium tuberculosis with more than 9 million individuals suffering from it in 2014. Traditional methods of detection are not efficient enough for its quick and reliable detection; therefore, it is imperative to develop methods of its detection in the early stages. Consequently, we report a highly sensitive and selective biosensor for detection of Mycobacterium tuberculosis. In this work, gold nanoparticles (AuNPs, dia. ∼6 nm, 1.81 wt% loading) are immobilized over reduced graphene oxide nanoribbons (RGONRs). An ssDNA/Au/RGONR electrode is prepared by immobilizing Au nanoparticles followed by covalent modification of Au nanoparticles with 5'SH-ssDNA. As per the best knowledge of the authors, the target DNA of Mycobacterium tuberculosis is detected using a ssDNA/Au/RGONR bioelectrode by cyclic voltammetry and chronoamperometric methods for the first time. With high detection efficiency (0.1 fM), the ssDNA/Au/RGONR bioelectrode exhibited better signal amplification and electrochemical response as compared to bare Au and RGONR electrodes. Additionally, the ssDNA/Au/RGONR bioelectrode displayed good linear response to different concentrations of target M. tuberculosis DNA. The ssDNA/Au/RGONR has shown excellent specificity (92%) to Mycobacterium tuberculosis target DNA as compared with non-complementary DNA. The Au/RGONR matrix has the potential to be used as an immobilization platform for single-stranded probe DNAs of different diseases other than tuberculosis reported here.

Nanoconfinement effects of chemically reduced graphene oxide nanoribbons on poly(vinyl chloride).

Polymeric nanocomposites with graphene-based nanocarbons (GNCs) have been extensively studied with emphasis on the percolation of nanofillers toward electrical, rheological, and mechanical reinforcement. In this study, we report an unusual indirect reinforcing phenomenon of highly defective GNCs dispersed in the poly(vinyl chloride) (PVC) matrix via densification of the polymer packing originating from nanoscale confinement. Herein, chemically reduced graphene oxide nanoribbons (C-rGONRs) are employed as a nanofiller. The inclusion of defective and oxygen-functionalized C-rGONRs resulted in a dramatic densification of the PVC host with extremely low C-rGONR loading, largely exceeding the theoretical calculation from a rule of mixture. Along with the densification, the glass transition temperature of PVC also increased by 28.6 °C at 0.1 wt% filler loading. Remarkably, the oxygen barrier property and mechanical toughness under tension for the PVC/C-rGONR nanocomposite were the maximum when the greatest densification occurred. The structure-property relationship of the nanocomposites has been discussed with an emphasis on the nanoscale confinement phenomenon.

RGO–RGONRs–Zn2SnO4 Composite with Three-Dimensional Hierarchical Structure for Use in Lithium-Ion Batteries

RGO–RGONRs–Zn2SnO4 composite with three-dimensional (3D) hierarchical structure has been formed from Zn2SnO4 nanoparticles grown on conducting reduced graphene oxide (RGO) and reduced graphene oxide nanoribbons (RGONRs) via a chemical co-reduction process. The presence of the RGONRs in this unique hybrid nanostructure prevents restacking of the graphene sheets and provides additional electron transport paths. Lithium-ion batteries using this 3D RGO–RGONRs–Zn2SnO4 composite as anode material displayed enhanced rate capability (510.6 mA h g−1 even at 1600 mA g−1) and cycling properties (779.8 mA h g−1 after 50 cycles at current density of 200 mA g−1).

Electrochemical behaviour of manganese & ruthenium mixed oxide@ reduced graphene oxide nanoribbon composite in symmetric and asymmetric supercapacitor

This paper reports the interaction of 3d-4d transition metal mixed oxide as simultaneous existence of M(3d) and M(4d) expectedly enhance the electrochemical performance of the resulting composite. Electrochemical performance of MnO2-RuO2 nanoflakes reduced graphene oxide nanoribbon composite (MnO2-RuO2@GNR) is intensively explored in symmetric and asymmetric supercapacitor assembly. In situ incorporation of graphene oxide nanoribbon (GONR) during synthesis provides efficient binding sites for growth of MnO2-RuO2 nanoflakes via their surface functionalities. The interconnected MnO2-RuO2 nanoflakes via GNR form a network with enhanced diffusion kinetics leading to efficient supercapacitor performance. Fabricated asymmetric supercapacitor reveals energy density 60Whkg−1 at power density 14kWkg−1. Based on the analysis of impedance data in terms of complex power, quick response time of supercapacitor reveals excellent power delivery of the device. Improved cycling stability after 7000 charge discharge cycles for symmetric and asymmetric supercapacitor highlights the buffering action of GNR and can be generalized for next generation high performance supercapacitor.