Reduced Graphene Oxide Copper Research Articles

Reduction of 4-Nitrophenol and Adsorption of Rhodamine B Using Reduced Graphene Oxide-Copper Sulfide Nanomaterial

Reduction of 4-Nitrophenol and Adsorption of Rhodamine B Using Reduced Graphene Oxide-Copper Sulfide Nanomaterial

Elimination of Curtobacterium sp. strain A7_M15, a contaminant in Prunus rootstock tissue culture production, using reduced graphene oxide–silver–copper and silver–selenium nanocomposites

BackgroundBacterial contamination poses a high risk to the successful establishment and maintenance of plant tissue cultures. The aim of this study was to identify the isolates representing the frequent bacterial contaminants of Prunus rootstock tissue cultures and to determine the most effective concentration of nanomaterials for Curtobacterium sp. strain A7_M15 elimination without a negative impact on explants.ResultsSix Curtobacterium sp. strains were isolated and identified, and the whole-genome sequence was obtained for strain A7_M15. Two nanocomposites, reduced graphene oxide–copper–silver and silver–selenium, with the highest bactericidal activity were selected for elimination of Curtobacterium sp. contamination in Gisela 5 rootstock tissue cultures. Both nanocomposites showed 100% inhibition of bacterial plaque formation on culture medium at concentrations of 100, 200 and 400 mg L-1 Ag (2 ×–8 × MBC). The quantity of Curtobacterium sp. on culture medium assessed using cfu enumeration was reduced by 92% and 74% in comparison to the positive control after treatment with reduced graphene oxide–silver–copper and silver–selenium at a concentration of 200 mg L-1 Ag, respectively. None of the tested concentrations resulted in a decrease in Curtobacterium sp. quantity in explants. Curtobacterium sp. was detected in donor Gisela 5 plants, indicating an endophytic character of this bacterium. The dry weight of explants was not negatively affected by the application of nanocomposites regardless of concentration, and no detrimental effect of either nanocomposite at 100 or 200 mg L-1 Ag on the surface covered by plants was observed.ConclusionsReduced graphene oxide–silver–copper and silver–selenium nanocomposites at 200 mg L-1 Ag effectively limited the Curtobacterium sp. presence in micropropagated Prunus rootstock without causing phytotoxicity; therefore, those treatments could be offered as prevention with a high activity against bacterial contamination in plant tissue cultures.Graphical

Hydrothermally Synthesized Reduced Graphene Oxide-Copper Sulfide Nanomaterial for Application As Supercapacitor

Hydrothermally Synthesized Reduced Graphene Oxide-Copper Sulfide Nanomaterial for Application As Supercapacitor

Reduced graphene oxide–copper thiotungstate composite for enhanced photoelectrochemical performance

Here, we have used a reduced graphene oxide (rGO) electron conducting scaffold to improve the charge transfer properties in the ternary transition metal chalcogenide Cu2WS4.

Facile synthesis of layered reduced graphene oxide–copper sulfide (rGO-CuS) hybrid electrode for all solid-state symmetric supercapacitor

A straightforward process for synthesis of hybrid porous electrode material composed of reduced graphene oxide (rGO) and copper sulfide (CuS) with layered structure on the stainless steel substrate is developed. As-synthesized hybrid electrode shows hexagonal crystal structure of CuS with 77 m2 gm−1 specific surface area and 22 nm average pore size. The specific capacitance obtained with rGO-CuS5 hybrid electrode is 1201 F g−1 at the sweep rate of 5 mV s−1 in 1 M LiClO4 aqueous electrolyte. The majority of charge stored by diffusion-controlled process indicates benefits of layered structures for solid-state energy storage. The rGO-CuS5-based hybrid symmetric supercapacitor delivers a specific capacitance (Cs) as high as 109 F g−1 at a sweep rate of 5 mV s−1 with polyvinyl alcohol (PVA)-LiClO4 gel electrolyte. Also, the specific energy of 44 Wh kg−1 and specific power of 1.4 kW kg−1 with 87% stability after 6000 cycles at an applied current of 5 mA are obtained. The simple process of synthesis of layered hybrid electrode material for flexible supercapacitor promises its use in smart textile and wearable electronic devices.

Low-cost electrochemical detection of l-tyrosine using an rGO-Cu modified pencil graphite electrode and its surface orientation on a Ag electrode using an ex situ spectroelectrochemical method.

A low cost reduced graphene oxide–copper hybrid nano thin-film modified Pencil Graphite Electrode has been employed to detect the l-tyrosine enantiomer. The free-standing rGO–Cu hybrid nano-thin film was prepared by a simple one-step liquid–liquid interface method. Electrochemical Cyclic Voltammetry, Differential Pulse Voltammetry, pH-dependent and scan rate dependent studies on bare PGE, Cu, rGO, and rGO–Cu for l-tyrosine have been explained in detail. The rGO–Cu modified PGE based biosensor exhibits good detection of l-tyrosine. The linear range detection limit was estimated to be 1 × 10−7 M. The calculated sensitivity is 0.4 μA ppm−1 mm2. This electroactive biosensor is easily fabricated and controlled and is cost-effective. The surface orientation of l-tyrosine on the Ag electrode at a particular potential and its comparison with vibrational DFT calculations have been studied for the first time.

Electrochemical Detection of Melamine by Using Reduced Graphene Oxide-Copper Nanoflowers Modified Glassy Carbon Electrode.

In this work, a robust and reliable electrochemical sensor was developed for sensitive detection of non-electroactive melamine (MEL) using a modified glassy carbon electrode with ascorbic acid (AA) as the active recognition element. To increase the current signal of AA, the working electrode was successively modified with l-arginine (l-Arg) and reduced graphene oxide–copper nanoflower composite. The voltammetry measurements denoted that the hydrogen bonding was formed between AA and MEL. Using the optimum conditions, the proposed enhanced sensor can detect MEL concentrations ranging from 10 × 10–9 to 9.0 × 10–8 M with a detection limit of 5.0 × 10–9 M that is proportional to the decrease of AA in the anodic peak current. Finally, the proposed sensor was successfully applied for the determination of MEL in commercial infant milk samples and good recovery values were obtained.

Efficacy of shape-monitored reduced graphene oxide–copper nanohybrids: anti-bacterial attributes for food safety and dye degradation studies

Usage perspective of morphology tailored reduced graphene oxide–copper hybrids is explored as antimicrobial and catalytic agent.

Based on reduced graphene oxide-copper sulfide-carbon nitride nanosheets composite electrochemiluminescence sensor for determination of gatifloxacin in mouse plasma.

A new method for determination of gatifloxacin hydrochloride (GAT) by reduced graphene oxide-copper sulfide (rGO-CuS) composite coupled with graphite-like carbon nitride nanosheets (g-C3N4 NSs) modified glassy carbon electrode was developed. In this work, rGO-CuS composite was synthesized by one-pot hydrothermal method and used for enhancing sensitivity of GAT. g-C3N4 NSs were synthesized as radiant agent. The sensor characteristics of electrochemistry and electrochemiluminescence (ECL) were investigated. The ECL intensity has enhanced four-fold after modifying with rGO-CuS composite. The results can be ascribed to the presence of rGO-CuS composite on the electrode surface that facilitates the electron transfer rate between the electroactive center of g-C3N4 NSs and the electrode. Under the optimum experimental conditions (photomultiplier tuber for 800 V, scan rate for 0.1 V/s, 0.1 mol/L PBS (pH 7.5) and 1.0 × 10-2 mol/L K2S2O8), the linear range for GAT was from 1.0 × 10-4 to 1.0 × 10-8 mol/L (R2 = 0.9991) with detection limit of 3.5 × 10-9 mol/L (S/N = 3). RSD for ECL intensity was 4.8% (n = 10). The recoveries of GAT in mouse plasma samples were from 98.36 to 104.7%. The sensor showed the advantages of low cost, high sensitivity and wide application in drug analysis.

Mussel-Inspired Architecture of High-Flux Loose Nanofiltration Membrane Functionalized with Antibacterial Reduced Graphene Oxide-Copper Nanocomposites.

Graphene-based nanocomposites have a vast potential for wide-ranging antibacterial applications due to the inherently strong biocidal activity and versatile compatibility of such nanocomposites. Therefore, graphene-based functional nanomaterials can introduce enhanced antibiofouling and antimicrobial properties to polymeric membrane surfaces. In this study, reduced graphene oxide-copper (rGOC) nanocomposites were synthesized as newly robust biocides via in situ reduction. Inspired by the emerging method of bridging ultrafiltration membrane surface cavities, loose nanofiltration (NF) membranes were designed using a rapid (2 h) bioinspired strategy in which rGOC nanocomposites were firmly codeposited with polydopamine (PDA) onto an ultrafiltration support. A series of analyses (SEM, EDS, XRD, XPS, TEM, and AFM) confirmed the successful synthesis of the rGO-Cu nanocomposites. The secure loading of rGOC composites onto the membrane surfaces was also confirmed by SEM and AFM images. Water contact angle results display a high surface hydrophilicity of the modified membranes. The PDA-rGOC functionalization layer facilitated a high water permeability (22.8 L m-2 h-1 bar-1). The PDA-rGOC modification additionally furnished the membrane with superior separation properties advantageous for various NF applications such as dye purification or desalination, as ultrahigh (99.4% for 0.5 g L-1 reactive blue 2) dye retention and high salt permeation (7.4% for 1.0 g L-1 Na2SO4, 2.5% for 1.0 g L-1 NaCl) was achieved by the PDA-rGOC-modified membranes. Furthermore, after 3 h of contact with Escherichia coli (E. coli) bacteria, the rGOC-functionalized membranes exhibited a strong antibacterial performance with a 97.9% reduction in the number of live E. coli. This study highlights the use of rGOC composites for devising loose NF membranes with strong antibacterial and separation performance.

Ultrasound assisted formation of reduced graphene oxide-copper (II) oxide nanocomposite for energy storage applications

The present exploration emphasizes on facile, one-pot sonochemical technique to fabricate reduced graphene oxide-Copper(II)oxide (rGO-CuO) nanocomposite where optimum amounts of CuO and functionalized-graphene phases synergistically establish superior electrochemical signature. Ultrasound assisted reduction of graphene oxide (GO) in presence of Cu(II) ions in ammoniacal medium followed by in-situ deposition of self-assembled CuO on rGO layers gives rise to the resultant rGO-CuO nanocomposite. The as-synthesized sample on spectroscopic, microscopic, surface and thermal analyses revealed stable, nanostructure morphology with large surface area opening the scope for its supercapacitive applications. The electrochemical performances investigated by cyclic voltammetry and chronopotentiometric charging/discharging cycles at a current density of 1Ag−1 in the potential window of −0.3V to +0.8V in 0.5M Na2SO4 aqueous medium, display appreciable specific capacitance (Cs=227Fg−1) of rGO-CuO nanocomposite compared to the reduced graphene oxide (rGO) (136.4Fg−1) and blank-copper oxide (30.1Fg−1) synthesized, and experimented under similar conditions. In aid executed electrochemical impedance spectroscopy for rGO-CuO nanocomposite suggests supercapacitive behavior with better electrical conductivity and ion transport performances assuring it a promising electrode material for future energy storage devices.

An ultrasensitive electrochemiluminescence sensor based on reduced graphene oxide-copper sulfide composite coupled with capillary electrophoresis for determination of amlodipine besylate in mice plasma

A new electrochemiluminescence (ECL) sensor based on reduced graphene oxide-copper sulfide (rGO-CuS) composite coupled with capillary electrophoresis (CE) was constructed for the ultrasensitive detection of amlodipine besylate (AML) for the first time. In this work, rGO-CuS composite was synthesized by one-pot hydrothermal method and used for electrode modification. The electrochemical and ECL behaviors of the sensor were investigated. More than 5-fold enhance in ECL intensity was observed after modified with rGO-CuS composite. The results can be ascribed to the presence of rGO-CuS composite on the electrode surface that facilitates the electron transfer rate between the electroactive center of Ru(bpy)32+ and the electrode. The ECL sensor was coupled with CE to improve the selectivity and the CE-ECL parameters that affect separation and detection were optimized. Under the optimum conditions, the linear ranges for AML was 0.008–5.0μg/mL with a detection limit of 2.8ng/mL (S/N=3). The method displayed the advantages of high sensitivity, good selectivity, wide linear range, low detection limit and fine reproducibility, and was used to analyze AML in mice plasma with a satisfactory result, which holds a great potential in the field of pharmaceutical analysis.

Layer-by-Layer Electrodeposited Reduced Graphene Oxide-Copper Nanopolyhedra Films as Efficient Platinum-Free Counter Electrodes in High Efficiency Dye-Sensitized Solar Cells

Efficient and low-cost platinum-free counter electrodes consisting of reduced graphene oxide (rGO) and copper nanopolyhedra (Cu) were fabricated on indium tin oxide (ITO) glass using a layer-by-layer electrochemical deposition. The structure and morphology of the as-fabricated counter electrodes were confirmed by X-ray diffraction, field-emission electron microscopy, and Raman spectroscopy. rGO-Cu-modified ITO electrodes, with different rGO loadings, were applied as catalytic counter electrodes in dye-sensitized solar cells (DSSCs) with an electrodeposited ZnO nanorod array as the photoanode. The current density−voltage curves and transient photocurrent measurements illustrate that the power conversion efficiency of the ZnO nanorod photoanode is significantly improved by the formation of rGO on the counter electrode. On the basis of electrochemical impedance spectroscopy, it is determined that the increased electrocatalytic activity of the rGO-Cu counter electrode is due to an enhanced conductivity of the counter electrodes. The maximum conversion efficiency is obtained for the rGO-Cu counter electrode with 0.5 mg ml−1 of rGO and has one and one half the efficiency achieved using a counter electrode modified only with Cu nanopolyhedra.

Synthesis of reduced graphene oxide–copper tin sulphide composites and their photoconductivity enhancement for photovoltaic applications

Graphene-based composites are attractive to effectively tune the intrinsic properties of inorganic semiconductors. We report the first study of band gap tuning and photoconductivity enhancement of reduced graphene oxide–Cu2SnS3 (G–CTS) composite. A simple solvothermal route has been used to synthesize G–CTS with and without a complexing agent in the reaction mixture. Raman and FTIR studies confirm the formation of G–CTS and reduced graphene oxide–Cu2SnS3 by the addition of complexing agent ethylenediaminetetraacetic acid (G–CTS(E)) during synthesis. Powder X-ray diffraction reveals the formation of cubic CTS structure in both the composites. Scanning electron microscopy (SEM) study has revealed microbar and nanorod morphologies in the composites. The wide absorption of composites has been measured using absorption spectroscopy study. The band gaps of G–CTS and G–CTS(E) have been calculated using the absorption spectra and found to be 1.33 and 1.61 eV, respectively. This study confirms the suitability of G–CTS and G–CTS(E) for photovoltaic applications. Photoconductivity study reveals that G–CTS(E) generates 60 % more current than G–CTS.

Reduced Graphene Oxide-Copper Sulfide Nanocomposites as Electrocatalysts in Quantum Dot Solar Cells: Overcoming the Platinum-Sulfur Relationship

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