rGO Nanostructures Research Articles

Improved photocatalytic performance of cobalt doped ZnS decorated with graphene nanostructures under ultraviolet and visible light for efficient hydrogen production

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with graphene CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}{\\rm S}$$\\end{document} rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity of CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}S$$\\end{document}rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene and CoxZn1-xSrGO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}{\\rm S \\, rGO}$$\\end{document} NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. The Co0.04Zn0.96S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_{0.04}{\\rm Zn}_{0.96}S$$\\end{document} rGO NSs sample had the highest photocatalytic activity, measured at 7648.9μmolh-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$7648.9 \\, \\upmu {\\rm mol} \\, {\\rm h}^{-1}$$\\end{document}. A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons, CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}S$$\\end{document} rGO NSs increased the photocatalytic hydrogen generation activity.

Enhanced Electrochemical Performance of Tin Oxide Quantum Dots on Reduced Graphene Oxide under Light.

The study utilized a simple and cost-effective approach to improve the photoelectrochemical (PEC) water-splitting performance of various materials, including reduced graphene oxide (rGO), tin oxide nanostructures (SnO2), and rGO/SnO2 composites. The composites examined were rS15, containing 15 mg of rGO and 45 mg of SnO2, and rS5, with 5 mg of rGO and 50 mg of SnO2, tested in a sodium hydroxide (NaOH) electrolyte. Notably, the rS5 electrode showed a significant increase in PEC efficiency in 0.1 M NaOH, achieving a peak photocurrent density of 13.24 mA cm-2 under illumination, which was seven times higher than that of pristine rGO nanostructures. This enhancement was attributed to the synergistic effects of the heterostructure, which reduced resistance and minimized charge recombination, thereby maximizing the catalytic activity across the various electrochemical applications. Furthermore, the rS5 anode demonstrated improved Tafel parameters, indicating faster reaction kinetics and lower overpotential for efficient current generation. These results highlight the potential for optimizing nanostructures to significantly enhance PEC performance, paving the way for advancements in sustainable water-splitting technologies.

A green approach to synthesis of Ag-doped CeO2 nanorods embedded reduced graphene oxide nanocomposite for excellent photocatalytic and antimicrobial activity

In this paper, the Ag-doped cerium oxide nanorods embedded reduced graphene oxide (Ag@CeO2/rGO) nanocomposite was synthesized via Punica Granatum peel extract for for photocatalytic degradation of methylene blue (MB) and 4-nitrophenol (4-NP). The microstructural results confirmed the successful decoration of Ag-doped CeO2 nanorods on rGO matrix. The photocatalytic properties, including photocatalytic degradation, charge transfer kinetics and photocurrent generation, are systematically investigated using electrochemical impedance spectroscopy (EIS), photocurrent transient response (PCTR) and open circuit voltage decay (OCVD). The results of photocatalytic dye degradation measurements indicated that Ag@CeO2/rGO nanocomposite is more effective than pristine CeO2 to degrade the MB dye, and the degradation rate reached 100 % in 60 min. The decomposition of MB with Ag@CeO2/rGO nanostructure followed first-order reaction kinetics with a reaction rate constant (Ka) of 0.0198 min−1. The EIS and OCVD measurements revealed that the Ag doping and incorporation of rGO could suppress the recombination probability in CeO2 by the separation of photo-generated electron–hole pairs, which leads to the enhanced photocurrent generation and photocatalytic activity. The photocurrent density of Ag@CeO2/rGO, CeO2/rGO and pristine CeO2 are 215, 167.4 and 98.8 mAcm−2, respectively.

Electro-sensing of biocide and its applications based on the Ru-doped TiO2 and reduced GO nanocomposite fabricated electrode

In this study, we utilized a carbon paste electrode (CPE) that had been modified with reduced graphene oxide nanoparticles (rGO) and ruthenium-doped TiO2 nanoparticles (Ru–TiO2) to conduct an electrochemical investigation of triclosan (TCS). To characterize the synthesized Ru–TiO2 nanoparticles, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized. Electrochemical impedance spectroscopy was employed to characterize the fabricated Ru–TiO2/rGO/CPE and bare CPE. “The heterogeneous rate constant, the pH study, the accumulation time, the scan rate, and the concentration fluctuation were investigated. Combining several electrocatalytic modifiers allows for the development of effective electrochemical sensors. Ru–TiO2 and rGO nanostructures are two examples of these modifiers. As a result of its great sensitivity, selectivity, and application to the measurement of TCS, nanostructured Ru–TiO2 and rGO are highly recommended in this research. At a pH of 9.2 in PBS, the sensitivity range of a Ru–TiO2/rGO/CPE was investigated by testing its response to a calibration plot of TCS concentrations ranging from 1.0 × 10−8 M to 2.2 × 10−7 M. Voltammetric techniques such as square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to determine the electrochemical components that comprise TCS. The developed sensor was also employed to detect and analyze TCS levels in actual samples, including those of fruits, vegetables, water, and soil.”

Edge-hosted CoFeB active sites with graphene nanosheets for highly selective nitrogen reduction reaction towards ambient ammonia synthesis

Electrocatalytic nitrogen reduction reaction (NRR) offers a suitable alternative to the conventional high energy intensive Haber–Bosch process for ambient ammonia (NH3) production without the release of greenhouse gases. Herein, a chemical reduction method is employed to effectively fabricate a hierarchical 3D nanostructure composed of CoFeB nanospheres precisely enveloped and interconnected with dynamically adaptable reduced graphene oxide (rGO) nanosheets for electrocatalytic NRR. Interconnected 3D CoFeB@ rGO nanostructures selectively reduced gaseous N2 to NH3 and demonstrated high Faradaic efficiency (31.6%) and NH3 yield rate (35 μg h−1 mg−1) at − 0.2 V in 0.05 M H2SO4, comparable to various state-of-the-art electrocatalytic materials for ambient NRR. Density functional theory (DFT) simulations additionally verify that interconnected CoFeB nanospheres with mechanically flexible graphene nanosheets are beneficial in lowering the energy threshold for N2 adsorption and successive protonation. First example of CoFeB@rGO heterostructures as electrocatalysts for high efficiency, pH-universal NRR to NH3 synthesis is highlighted in this study.

Electrocatalytic evaluation of β-SnWO4/rGO nanostructure for low-level urea detection

Electrocatalytic evaluation of β-SnWO4/rGO nanostructure for low-level urea detection

Hierarchical In2O3/rGO nanostructures with uniformly distributed In2O3 nanoparticles: microwave-assisted synthesis and improved NO-sensing performance

Enormous p–n heterojunction interfaces and the synergistic effect of In2O3 and rGO species effectively decreased the working temperature for NO detection.

DESENVOLVIMENTO DE BIOSSENSOR NO DOPING ESPORTIVO COM DEXAMETASONA

ABSTRACT Introduction: Dexamethasone is a type of drug that is considered a steroid. It belongs to a class of drugs known as corticosteroids. Objective: Develop an electrochemical sensor of dexamethasone in a pharmaceutical sample using electrodes modified with nanostructures of MnO2 and reduced graphene oxide (MnO2/rGO). The glassy carbon electrodes (GCE) used to make the GO nanostructures were first modified using a modified Hummers technique before electrochemically reduced. Methods: MnO2 nanomaterials were electrochemically deposited on rGO/GCE. SEM structural investigation indicated vertical tetragonal crystal development of -MnO2 nanostructures in sprayed rGO nanostructures. Results: Because of the high composite surface area, multiple exposed active sites, and the synergistic effect of MnO2 and rGO, the electrocatalytic reaction to dexamethasone of MnO2/rGO/CPE was shown to be broad, selective, stable, and sensitive in electrochemical tests using amperometry. It was established that the linear range, sensitivities, and detection limit of the sensor are 0 to 260 µM, 4.6153µA/µM and 0.005 µM, respectively. The MnO2/rGO/CPE was tested for accuracy and applicability in determining dexamethasone in pharmacological and human urine samples. Conclusion: The results revealed that the sensor could prepare acceptable recovery (96.34%) and RSD (3.58%), suggesting that it could be used as a reliable dexamethasone sensor in clinical samples. Level of evidence II; Therapeutic studies - Investigation of treatment outcomes.

Flexibility of Key Electronic and Optical Properties of Reduced Graphene Oxide Through Its Controlled Synthesis

Recently, graphene oxides (GOs), reduced GO (rGO), and their derivatives have been focused on as a superior flexible material due to having easy processability and high carrier mobility. Here, we report an inexpensive green synthesis of GO/rGO at a relatively low temperature of 150 °C. The scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Raman, Fourier transformed IR (FTIR), and UV–visible spectroscopy confirm the successful fabrication of rGO with an enhanced carbon–0carbon (sp2/sp3) component with an enhanced carbon-to-oxygen ratio (C/O) from 0.93 to 2.76. Here, a work function tuning of 5.6–4.5 eV, a bandgap modulation of 3.93–2.63 eV, a charge carrier density tuningfrom <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.12\times10$ </tex-math></inline-formula> 16 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.14\times10$ </tex-math></inline-formula> 21 cm−3, and a mobility tuning from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.51\times10$ </tex-math></inline-formula> −2 to 59.663 cm2/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}\cdot \text{s}$ </tex-math></inline-formula> are made through its controlled reduction of GOs, which are much better than the results obtained at high temperature >1000 °C. The flexible nature of both electronic and optical properties of rGO nanostructures assures it as an excellent material for electronics and optoelectronics devices.

Effects of Graphene Oxide and Reduced Graphene Oxide Nanostructures on CD4+ Th2 Lymphocytes.

The activation of T helper (Th) lymphocytes is necessary for the adaptive immune response as they contribute to the stimulation of B cells (for the secretion of antibodies) and macrophages (for phagocytosis and destruction of pathogens) and are necessary for cytotoxic T-cell activation to kill infected target cells. For these issues, Th lymphocytes must be converted into Th effector cells after their stimulation through their surface receptors TCR/CD3 (by binding to peptide-major histocompatibility complex localized on antigen-presenting cells) and the CD4 co-receptor. After stimulation, Th cells proliferate and differentiate into subpopulations, like Th1, Th2 or Th17, with different functions during the adaptative immune response. Due to the central role of the activation of Th lymphocytes for an accurate adaptative immune response and considering recent preclinical advances in the use of nanomaterials to enhance T-cell therapy, we evaluated in vitro the effects of graphene oxide (GO) and two types of reduced GO (rGO15 and rGO30) nanostructures on the Th2 lymphocyte cell line SR.D10. This cell line offers the possibility of studying their activation threshold by employing soluble antibodies against TCR/CD3 and against CD4, as well as the simultaneous activation of these two receptors. In the present study, the effects of GO, rGO15 and rGO30 on the activation/proliferation rate of these Th2 lymphocytes have been analyzed by studying cell viability, cell cycle phases, intracellular content of reactive oxygen species (ROS) and cytokine secretion. High lymphocyte viability values were obtained after treatment with these nanostructures, as well as increased proliferation in the presence of rGOs. Moreover, rGO15 treatment decreased the intracellular ROS content of Th2 cells in all stimulated conditions. The analysis of these parameters showed that the presence of these GO and rGO nanostructures did not alter the response of Th2 lymphocytes.

Microwave-Assisted Chemical Co-reduction of Pd Nanoparticles Anchored on Reduced Graphene Oxide with Different Loading Amounts

Microwave-assisted Palladium/Reduced Graphene Oxide (Pd/RGO) synthesis was effectively carried out in this study, which looked at the effects of different Pd loading weights in Graphene Oxide (GO) on its physicochemical qualities. The Tour technique was used to make GO, with a KMnO4:graphite weight ratio of 3.5. Meanwhile, Pd/RGO was synthesized utilizing the in-situ reduction method of one-pot synthesis with ascorbic acid as the green reducing agent, yielding Pd-0.5/RGO, Pd-1.0/RGO, and Pd-2.0/RGO, respectively, with variations in Pd loading weight of 0.5, 1.0, and 2.0%. XRD, FTIR, SAA, SEM-EDX, and TEM were used to examine all material characterizations. As a result, Pd-1.0/RGO had the largest surface area of 65.168 m2/g among the Pd-based materials, with a pore volume of 0.111 cc/g, the pore diameter of 3.316 nm, Pd crystallite size of 28.29 nm, RGO nanostructure dimension of 3.37 × 28.53 nm, and reduction level (C/O) of 3.02. This material also contains specific functional groups, including O-H, C-H, CO2, C=C, C=O, and C-O, based on FTIR spectra. Therefore, optimal weight loading of metal on the surface of the supporting material will provide a large material surface area. Increasing the surface area of the material improves its performance as a catalyst.

Enhanced Photocatalytic Removal of Hexavalent Chromium over Bi12TiO20/RGO Polyhedral Microstructure Photocatalysts.

A Bi12TiO20/RGO photocatalyst with polyhedron microstructure was fabricated via the template-free hydrothermal method, and the visible-light-induced photocatalytic activity of the prepared Bi12TiO20 was also evaluated by the photocatalytic reduction of heavy metal pollutants. The structures and optical properties of the prepared Bi12TiO20/RGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The effects of the reaction time and mineralizer concentration on the formation of the Bi12TiO20 polyhedral microstructure were analyzed. The enhanced photocatalytic performances of Bi12TiO20/RGO were observed which were ascribed to the combination of the Bi12TiO20 microstructure induced photogenerated charges and the RGO nanostructure as a photogenerated charges carrier. The effect of organic acids, p-hydroxybenzoic acid (PHBA), chloroacetic acid, and citric acid on the Cr(VI) photocatalytic reduction was also discussed. This work provides an insight into the design of the bismuth-based microstructure photocatalyst towards the application for environment purification of heavy metals.

Wrinkled Flower-Like rGO intercalated with Ni(OH)2 and MnO2 as High-Performing Supercapacitor Electrode

This study reports a simple one-step hydrothermal method for the preparation of a Ni(OH)2 and MnO2 intercalated rGO nanostructure as a potential supercapacitor electrode material. Having highly amorphous rGO layers with turbostratic and integrated wrinkled flower-like morphology, the as-prepared electrode material showed a high specific capacitance of 420 F g–1 and an energy density of 14.58 Wh kg–1 with 0.5 M Na2SO4 as the electrolyte in a symmetric two-electrode. With the successful intercalation of the γ-MnO2 and α-Ni(OH)2 in between the surface of the as-prepared rGO layers, the interlayer distance of the rGO nanosheets expanded to 0.87 nm. The synergistic effect of γ-MnO2, α-Ni(OH)2, and rGO exhibited the satisfying high cyclic stability with a capacitance retention of 82% even after 10 000 cycles. Thus, the as-prepared Ni(OH)2 and MnO2 intercalated rGO ternary hybrid is expected to contribute to the fabrication of a real-time high-performing supercapacitor device.

Enhanced dielectric and electrostatic energy density of electronic conductive organic-metal oxide frameworks at ultra-high frequency

High-density energy materials comprise high dielectric strength, and rapid charge transport leads to improved microwave absorbance, maximum electromagnetic wave (EM) attenuation, and wideband characteristics. This work exhibits hierarchical polyaniline (PANI) functionalized polycrystalline hybrid units. Comprehensive band structures, increased electron conduction, high charge polarization, and definite EM wave absorption could be tuned by the featured morphologies. Filler material's (RGO/ZnO) intercalated structures have substantial free space volume. It could facilitate notable dielectric permittivity (∼2562 F m−1), give rise to higher charge polarization and excellent charge storage performance (∼112 F). This electrostatic charge proficiency could recognize with generous electron density corresponding to stimulated surface charge density (σs, ∼8.66×103 C m−2). Quality factor (Q) of 0.056 (∼ 7.1×106Hz) with minimized losses attributed to higher energy density (Ue, ∼1530 J cm−3) at low electric field strength ∼ 450 V m−1, which could resemble a variable Ue performance at lower to a higher percolation threshold voltage. Incorporated ZnO and RGO nanostructures are well organized, with the PANI matrix providing good interfacial adhesion. It significantly raises the EM wave losses (– 28 dB) of ∼0.300 mm thick specimen at ∼ 18.42 GHz. We envisioned that the multifunctional response of the PANI-RGO-ZnO 2:1 hybrid might manifest potential energy storage and microwave absorption as electrode materials that may be useful in solid-state devices used in modern communication systems.

White LED active α-Fe2O3/rGO photocatalytic nanocomposite for an effective degradation of tetracycline and ibuprofen molecules

The formation of phase pure magnetically separable α-Fe2O3 and α-Fe2O3/rGO nanostructures were achieved through a simple hydrothermal technique. The properties of synthesized materials were investigated through different analytical techniques. The formation of phase pure FO and FO/rGO nanostructures were confirmed by XRD analysis with crystallite size of about ∼42 nm and ∼65 nm, respectively. The morphological analysis reveals the formation of sphere-like nanoparticles with high agglomeration. The UV-DRS analysis clearly shows the enhanced visible-light activity of FO/rGO nanoparticles. The BET analysis revealed the mesoporous property of FO/rGO nanocomposite. The enhancement in the photoinduced charge transfer process is observed after including rGO nanoparticles with FO. The photocatalytic efficiency of nanomaterials was analyzed using tetracycline and ibuprofen as model organic pollutants under white LED irradiation. The enhanced photocatalytic degradation ability of FO/rGO nanocomposite is studied against both tetracycline and ibuprofen molecules.

Efficient energy storage performance of in situ grown Co3V2O8-RGO composite nanostructure for high performance asymmetric Co3V2O8-RGO//RGO supercapacitors and consequence of magnetic field induced enhanced capacity

In this work, cobalt vanadate/reduced graphene oxide (Co 3 V 2 O 8 /RGO) composite nanostructure has been synthesized via in-situ reduction of graphene oxide (GO) in the presence of cobalt chloride and sodium metavanadate through hydrothermal following post calcinations treatment. Characterizations through various techniques have been performed to probe the physicochemical properties of Co 3 V 2 O 8 /RGO, RGO and Co 3 V 2 O 8 nanostructures . Our Results show that because of the synergistic effect , Co 3 V 2 O 8 /RGO composite nanostructure exhibits superior electrochemical properties as compared to bare RGO and Co 3 V 2 O 8 . At a current density of 0.5 A/g the specific capacity has been recorded to be 118.82, ∼179, and ∼241.67 Cg -1 in case of Co 3 V 2 O 8 , RGO and Co 3 V 2 O 8 /RGO nanostructures, respectively. Moreover, Co 3 V 2 O 8 /RGO composite nanostructure (positive electrode) and RGO (negative electrode) have been employed to prepare the asymmetric supercapacitor , exhibited high specific capacity (127.62Cg -1 ), energy density (28.36 Whkg −1 ), and power density (400 Wkg -1 ) at a current density 0.5 A/g. This asymmetric supercapacitor shows excellent capacity retention (∼91.64%) and columbic efficiency (∼98.61%) measured at a current density of 5 A/g after 10,000 charge/discharge cycles. More importantly, a dramatic increase ∼170% (344 Cg -1 ) and ∼67% (185 Cg -1 ) in the specific capacity have been recorded at a current density of 0.5 A/g and 1.0 A/g, respectively when asymmetric supercapacitor device is subjected to an external magnetic field of strength of 0.5 T. Additionally, under the applied magnetic field , capacity retention ∼97.75% and columbic efficiency ∼98.84% has been recorded at a current density of 5 A/g after 10,000 cycles. • Synthesis of Co 3 V 2 O 8 /RGO composite nanostructure via a facile in-situ reduction. • Co 3 V 2 O 8 /RGO nanostructure exhibited specific capacity of ~242 Cg -1 at 0.5 Ag -1 . • Co 3 V 2 O 8 /RGO exhibits ~103% higher specific capacity compare to bare Co 3 V 2 O 8 NPs. • ASc exhibits energy density ~28.36 Whkg -1 and power density ~ 400 Wkg -1 at 0.5 Ag -1 . • Capacity retention ~91.64 % and columbic efficiency ~98.61 % at 5 Ag -1 after 10,000 cycles. • Magnetic field induced ~170% enhanced capacity at 0.5 Ag-1.

Growth of rGO nanostructures via facile wick and oil flame synthesis for environmental remediation

Oil spills into ocean or coastal waters can result in significant damage to the environment via pollution of aquatic ecosystems. Absorbents based on reduced graphene oxide (rGO) foams have the capacity to remove minor or major oil spills. However, conventional chemical synthesis of rGO often uses petrochemical precursors, potentially harmful chemicals, and requires special processing conditions that are expensive to maintain. In this work, an alternative cost-effective and environmentally friendly approach suitable for large-scale production of high-quality rGO directly from used cooking sunflower oil is discussed. Thus, produced flaky graphene structures are effective in absorbing used commercial sunflower oil and engine oil, via monolayer physisorption in the case of used sunflower and engine oils facilitated by van der Waals forces, π–π stacking and hydrophobic interactions, π-cation (H+) stacking and radical scavenging activities. From adsorption kinetic models, first-order kinetics provides a better fit for used sunflower oil adsorption (R2 = 0.9919) and second-order kinetics provides a better fit for engine oil adsorption (R2 = 0.9823). From intra-particle diffusion model, R2 for USO is 0.9788 and EO is 0.9851, which indicates that both used sunflower and engine oils adsorption processes follow an intra-particle diffusion mechanism. This study confirms that waste-derived rGO could be used for environmental remediation.

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.

Mixed‐phase MoS 2 decorated reduced graphene oxide hybrid composites for efficient symmetric supercapacitors

In this work, we demonstrated the phase-tuned MoS2 layers (2H- MoS2, 1 T- MoS2, and 2H/1 T-MoS2) using a one-pot reaction, scientifically significant due to their impermeable characteristics. Strongly-bonded, vertically-aligned layers were perceived by transmission electron microscopy (TEM) for 2H/1 T-MoS2 layers. The spacing between the two layers was expanded to 0.67 nm, which is favorable for intercalation process. Further, mixed-phase MoS2 sheets were successively blended with reduced graphene oxide (rGO) to form 2H/1 T-MoS2@rGO hybrid. Spectroscopic studies verified the formation of phase-tuned MoS2 and 2H/1 T-MoS2@rGO hybrid. The resulting 2H/1 T-MoS2@rGO hybrid TEM micrograph shows the layered MoS2 lattices decorated rGO nano-structure. Symmetric supercapacitors constructed from 2H/1 T-MoS2@rGO hybrid electrodes demonstrated improved storage capacity with solid pseudo-capacitive behavior compared to the pure phases. Surface-modified 2H/1 T-MoS2@rGO nanostructures exhibited a high energy density of 55 Wh·kg−1 at a power density of 3 kW·kg−1 with a symmetric capacitance of 275 F·g−1 at a current density of 1 A·g−1, along with an excellent cyclic constancy (~97% capacity after 5000 cycles).

Fe3O4@Au/reduced graphene oxide nanostructures: Combinatorial effects of radiotherapy and photothermal therapy on oral squamous carcinoma KB cell line

Combination therapy including radiotherapy (RT) and photothermal therapy (PTT), as an alternative treatment for cancer treatment, recently has generated substantial interest. Graphene-based nanocarbons and gold content metallic nanoparticles, as one of the most attractive materials with their extraordinary physical and chemical properties, are extremely useful in this regard. We herein reported the effects of combination of cancer therapy including RT (doses of 2 and 4 Gy) and PTT (808 nm laser irradiation, NIR irradiation) as radio-photothermal therapy (RPTT) of KB oral squamous carcinoma cell line in the presence of Fe3O4@Au/reduced graphene oxide (rGO) nanostructures (NSs) at different concentrations. Fe3O4@Au/rGO NSs with different rGO contents have been synthesized by hydrothermal reaction method. They characterized by XRD, FE-SEM, TEM, EDS, FTIR and TGA. Cell viability for cytotoxicity, RT, PTT and RPTT were studied by MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. High photothermal conversion efficiency of Fe3O4@Au/rGO NSs reaches to 61%. The resulting Fe3O4@Au NPs with approximate size of about 10–60 nm covered the rGO nanosheets with 40 wt% rGO at concentration of 20 μg ml−1, exhibited satisfactory cytotoxicity. They provided significant cell destruction under RT, PTT and specially RPTT in dose of 4 Gy. Furthermore, they have good biocompatibility on the healthy cells. Our results show that Fe3O4@Au/rGO NSs integrated with radiosensitization, photothermal therapy and their combination promising for nanomedicine and clinical applications.