Reduced Graphene Oxide Nanosheets Research Articles

Efficient capture of airborne PM by membranes based on holey reduced graphene oxide nanosheets

Particulate matter (PM) has long been considered an urgent atmospheric problem due to its harmful effects on the ecological environment and human health. Herein, we demonstrate the fabrication of membranes based on holey-reduced graphene oxide (H-RGO) nanosheets with different hole sizes to efficiently remove PM from the air. Etching KMnO4 and Co3O4 nanoparticles embedded on RGO nanosheets obtained the H-RGO nanosheets, followed by ordinary vacuum filtration. The H-RGO nanosheets show abundantly porous features with a rich hole (average pore size of 12.97 nm) on the planar H-RGO nanosheets, which is beneficial to the mass transfer of the as-prepared membrane. Thanks to its porously hierarchical architectures, the H-RGO-based filter shows excellent performance for the capture of PM, e.g., high efficiency of greater than 99 % for PM1.0, PM2.5, PM5.0, and PM10, respectively. Interestingly, the inherent hydrophobicity of H-RGO nanosheets, the as-prepared membrane exhibits superior humidity resistance with a high filtration efficiency of nearly 100 % observed even at high humidity (96 ± 2 % relative) over a continuous 18-hour test, which is considerably better than hydrophilic filtration materials. Taking advantage of its physicochemical stability, unique porously hierarchical architectures, and excellent PM capture performance, the H-RGO membranes may have great potential for practical separation, PM removal, and air cleaning applications.

Evaluation of HER and OER electrocatalytic activity over RuO2–Fe2O3 nanocomposite deposited on HrGO nanosheets

Electrochemical water-splitting efficiency is determined by both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts. Therefore, designing a bi-functional configuration is essential for an efficient HER and OER catalytic performance under the same experimental conditions. In this study, a novel ionic pentanuclear complex of the type [Ru(dmbpy)3]3[Fe(CN)6]2, where dmbpy = 4,4′-dimethyl-2,2′-bipyridine, has been synthesized and characterized by structural (X-ray), analytical (CHN), and spectral (FT–IR, UV–Vis) methods. Highly reduced graphene oxide nanosheets (HrGO NSs) supported RuO2–Fe2O3 nanocomposite were prepared by an impregnation method using [Ru(dmbpy)3]3[Fe(CN)6]2 as a precursor and HrGO NSs as a support. The RuO2–Fe2O3/HrGO NSs nanocomposite was characterized by means of spectroscopy (XPS, FT–IR, and FT–Raman), surface area (BET/BJH), diffraction (XRD), thermal (TGA), and electron microscopy (TEM and FE–SEM) analyses. The electrocatalytic HER, OER, and overall water-splitting activities of RuO2–Fe2O3/HrGO NSs, RuO2–Fe2O3, RuO2/HrGO, Fe2O3/HrGO, and HrGO in 1 M KOH solution were studied. According to the overpotentials of −239 and 386 mV (vs. RHE) at 10 mA cm−2 current density, the exchange current densities of 0.0641 and 0.389 × 10−4 mA cm−2, the Tafel slopes of 97 and 67 mV dec−1, and the charge-transfer resistance values of 38.57 and 31.5 Ω for HER and OER, respectively, the RuO2–Fe2O3/HrGO NSs nanocomposite possesses bi-functional catalytic capabilities toward both hydrogen and oxygen evolution reactions. The catalytic performance is enhanced by the high surface area, the high number of catalytically active sites, the presence of nanoparticles with different morphologies, and the synergistic interaction between RuO2–Fe2O3 nanoparticles and HrGO nanosheets.

Hollow cobalt selenide nanospheres wrapped with reduced graphene oxide nanosheets as electrodes for hybrid supercapacitor

In this work, hollow CoSe2 nanospheres wrapped with reduced graphene oxide (rGO) nanosheets are fabricated through combining the self-templated method with the electrostatic self-assembled method followed by heat treatment. The experimental results indicate that rGO nanosheets can act as space separator and structural protector to reduce the aggregation and nanoparticle size of hollow CoSe2 nanospheres and meanwhile maintain their structural integrity. Density functional theory calculations indicate that the wrapping of rGO nanosheets not only increases the electrical conductivity but also reduces the adsorption energy of OH– at the CoSe2/rGO interface. Accordingly, hollow CoSe2/rGO nanocomposites yield specific capacities of 757C g−1 at 3 A/g and 552C g−1 at 20 A/g, as well as a capacity retention of 92 % over 5000 cycles at 10 A/g. When coupled with N-doped carbon nanotube-based negative electrode, the fabricated HSC device delivers an energy density of 50.1 W h kg−1 at 800 W kg−1 as well as maintains a capacity retention of 94 % after 5000 cycles. Our work offers a further understanding of the charge storage mechanism of hollow CoSe2/rGO nanocomposites and may be extended to develop other advanced nanostructured metal selenides/graphene electrodes.

High-performance non-enzymatic glucose sensing on nanocomposite electrocatalysts of nickel phthalocyanine nanorods and nitrogen doped-reduced graphene oxide nanosheets

Highly stable and efficient electrocatalytic materials are essential for developing high-performance non-enzymatic fourth-generation glucose biosensors. In this regard, hybrid materials incorporating metallophthalocyanines and carbon-based nanostructures are particularly interesting. A nanocomposite of nitrogen-doped reduced graphene oxide nanosheets and nickel phthalocyanine nanorods (N-rGONs|NiPcNRs) was prepared. N-rGONs|NiPcNRs were highly efficient and stable electrocatalysts for non-enzymatic d-glucose electrooxidation in alkaline media. Spectroscopic, microscopic, and electrochemical methods were used to characterize and evaluate the electrocatalytic performance of the N-rGONs|NiPcNRs. The remarkable electrocatalytic activity of N-rGONs|NiPcNRs originated from the in-situ transformation and formation of polymeric O-Ni-O oxo-bridge in alkaline electrolyte and the excellent electroconductivity of the N-rGONs. The N-rGONs|NiPcNRs with the optimum ratio of NiPcNRs to N-rGONs presented an efficient formation of the Ni-O-Ni oxo-bridge and d-glucose electrooxidation compared to N-rGONs and NiPcNRs alone. Thus, the fabricated GCE|N-rGONs|NiPcNRs glucose sensor showed an excellent analytical performance with a high sensitivity of 1458 µA.mM−1.cm−2 and a detection limit of 1.43 µM (S/N = 3) using cyclic voltammetry. For online glucose detection using chronoamperometry, a sensitivity of 358.9 µA.mM−1.cm−2 with a detection limit of 5.0 µM (the lowest concentration that could be discriminated from the buffer using GCE|N-rGONs|NiPcNRs) and a fast response time of 0.80 s was obtained. The high sensitivity of CV (1458 µA.mM−1.cm−2) allowed for lower limits of detection (1.34 µM). The fabricated sensor was successfully applied for the determination of d-glucose levels in serum samples, demonstrating its potential for monitoring glucose levels in diabetes patients.

Constructing VS4 nanorods anchored on reduced graphene oxide surface to enhance rate capability as sodium-ion battery anode

The dense VS4 nanorods laterally anchored on the bilateral surface of reduced graphene oxide nanosheets (VS4@rGO) are successfully constructed through a simple hydrothermal method. Benefiting from the synergistic effect of VS4 nanorods with abundant energy storage sites, rGO nanosheets with high electrical conductivity and their interfacial lattice interaction and VC bond, VS4@rGO sodium-ion battery (SIB) anode shows the superior rate capability with the specific capacity of 264, 176 and 114 mAh/g at 1, 5 and 10 A/g after 1000 cycles, respectively. The work provides a high-performance anode material for SIB and a new design idea for metal sulfides/carbon heterostructures in energy storage field.

Docking studies and thiourea-mediated reduced graphene oxide nanosheets' larvicidal efficacy against Culexquinquefasciatus

The larvicidalproperty of graphene oxide (GO) and thiourea-reduced graphene oxide (T-rGO)was assessed against Culexquinquefasciatuslarvae. A simple water-soluble material synthesis method was used. The transformation of graphene into graphene oxide was accomplished in a single step. Under mild conditions, grapheneoxidewasdissolved in water to form a solution. Structure, optical, and microstructural features of the synthesized samples wereevaluatedusing a variety of analytical tools to compare the samples. Both GO and RGO, as well as GO, showed strong larvicidal potential when used against the third instar larvae of the Culexquinquefasciatus mosquito, with LC50and LC90values of 1.71 and 5.17 ppm and 1.89 and 5.00 ppm, respectively.As a result, our study showed that all of the GO and T-rGO under investigation create larvicidal compounds that could be employed to support efforts to control mosquito populations. It also offers an alternative method for producing GO and rGO on a big scale, which may be used in the future for a variety of biomedical applications.The binding efficacy of the active compounds against AChE1 was studied using Auto dock and the results were observed to be highly promising.

Mass ratio-dependently tunable enhancement of the optical nonlinearities of SnO2/RGO composites

The composite of graphene and semiconductor nanoparticles has attracted increasing interest in the search for novel nonlinear optical materials. Herein, composites of reduced graphene oxide (RGO) and SnO2 nanoparticles with different mass ratios were synthesized via a facile hydrothermal method. The structural morphology and basic physical properties of the SnO2/RGO composites were characterized using TEM, SEM, XRD, Raman, XPS and UV–Vis spectra, indicating that SnO2 nanoparticles were uniformly anchored on the surface of graphene nanosheets through covalent and partial-ionic bonds. The third-order optical nonlinearities of the composites were studied for the first time by the Z-scan technique using a picosecond laser at 532 nm. It was found that the composites demonstrated saturable absorption and positive nonlinear refraction properties, and both were significantly enhanced compared with pure SnO2 nanoparticles and RGO nanosheets, and the enhancement was tunable with the variation of SnO2:GO mass ratio. The maximum saturable absorption coefficient and the third-order susceptibility of the as-prepared SnO2/RGO composites were obtained to be −2.93×10–11 m W−1 and 2.25 × 10–11 esu, respectively. The maximum saturable absorption modulation depth obtained was 10% with the corresponding saturation light intensity of 0.3 GW cm−2. Moreover, the optimised third-order susceptibility of SnO2/RGO was found much greater than many other materials ever studied. Several involved factors contributing to the nonlinearities were discussed. The results propose that the third-order optical nonlinearities of SnO2/RGO and other similarly structured composites can be potentially tuned to meet certain application requirements of nonlinear optical devices by controlling the mass ratio of semiconductor to graphene.

Jamming carbonaceous nanofiller in the continuous phase and at the blend interface for phenomenal improvement in the overall physico-mechanical properties of compatibilized thermoplastic elastomer

Reduced graphene oxide (RGO) nanosheets have been selectively jammed in the continuous polypropylene (PP) phase and at the blend interface of random terpolymer of ethylene, acrylic ester and maleic anhydride (EAMAT) compatibilized PP and epichlorohydrin rubber (ECH) based thermoplastic elastomer (TPE). The presumptions from the contact angle studies regarding the preferential localization of RGO in the continuous PP phase and at the blend interface of compatibilized PP/ECH/EAMAT/RGO TPE nanocomposite have been analyzed via field emission scanning electron microscopy and atomic force microscopy. The presence of RGO in the continuous PP phase and at the blend interface results in a phenomenal improvement in the mechanical, rheological and viscoelastic properties of the compatibilized PP/ECH/EAMAT/RGO TPE nanocomposites. X-ray diffraction studies of the strained compatibilized PP/ECH/EAMAT/RGO TPE nanocomposite testify that, during straining, the RGO nanosheets help the PP chains to orient and consequently there is a prominent improvement in the overall physico-mechanical properties.

The influence of the oxidation method on the properties of reduced graphene oxide

Derivatives of graphene have become important materials due to their excellent properties. Graphene oxide and reduced graphene oxide are especially interesting because they are produced relatively easily, cheaply and quickly. Among many possible applications, reduced graphene oxide is a good candidate for sensor applications. Its properties can be controlled at the production stage. The precursor used and the method of oxidation have a significant influence on its properties. Therefore, it is worth take a closer look at them. In this paper we analyse the influence of the oxidation method on the size of the reduced graphene stock which determine the sensitivity of the rGO layer. We used AFM microscopy for this purpose. Full Text: PDF ReferencesS.M. Majhi, A. Mirzaei, H.W. Kim, S.S. Kim, "Reduced Graphene Oxide (rGO)-Loaded Metal-Oxide Nanofiber Gas Sensors: An Overview", Sensors 21, 4 (2021). CrossRef M. Pumera, "Graphene-based nanomaterials for energy storage", Energy Environ. Sci. 4 3 (2011). CrossRef X. Yu, H. Cheng, M. Zhang, Y. Zhao, L. Qu, G. Shi, "Graphene-based smart materials", Nat. Rev. Mater. 2, 9 (2017). CrossRef M.Y. Xia, Y. Xie, C.H. Yu, G.Y. Chen, Y.H. Li, T., Zhang, Q. Peng, "Graphene-based nanomaterials: the promising active agents for antibiotics-independent antibacterial applications", J. Control. Release 10 (2019). CrossRef X. Zhu, Y. Zhou, Y. Guo, H. Ren, C. Gao, "Nitrogen dioxide sensing based on multiple-morphology cuprous oxide mixed structures anchored on reduced graphene oxide nanosheets at room temperature", Nanotechnology 30 45 (2019). CrossRef Z. Wu, Y. Wang, S. Ying, M. Huang, C. Peng, "Fabrication of rGO/Cuprous Oxide Nanocomposites for Gas Sensing", IOP Conf. Ser.: Earth Environ. Sci. 706, 1 (2021). CrossRef S. Pei, H.M. Cheng, "The reduction of graphene oxide", Carbon 50, 9 (2012). CrossRef K. Spilarewicz-Stanek, A. Kisielewska, J. Ginter, K. Bałuszyńska, I. Piwoński, "Elucidation of the function of oxygen moieties on graphene oxide and reduced graphene oxide in the nucleation and growth of silver nanoparticles", RSC Adv. 6, 65 (2016). CrossRef R. Muzyka, S. Drewniak, T. Pustelny, M. Sajdak, Ł. Drewniak, "Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy Statistical Analysis", Materials 14, 4 (2021) CrossRef B. Lesiak, G. Trykowski, J. Tóth, et al. "Chemical and structural properties of reduced graphene oxide—dependence on the reducing agent", J Mater. Sci. 56 (2021). CrossRef .

Phthalocyanine-mediated interfacial self-assembly of magnetic graphene nanocomposites toward low-frequency electromagnetic wave absorption

Exploring multi-component composite is promising for advanced electromagnetic wave (EMW) absorption materials, yet challenged by balancing low-frequency absorption and cost-effective preparation mode. Herein, a series of dielectric-magnetic nanocomposites are fabricated as EMW absorbers via facile phthalocyanine-mediated interfacial self-assembly approach. Phthalocyanine could act as a functional reagent to modify magnetic Fe3O4 nanosphere and guarantee the self-assembly with reduced graphene oxide nanosheet simultaneously. Owing to the flexible self-assembly, the as-synthesized ternary nanocomposite exhibits highly tunable EMW absorption performance toward low-frequency absorption. The minimum reflection loss reaches −49.0 dB (99.998 % wave absorption) simultaneously at a low frequency of 5.4 GHz and a high frequency of 8.3 GHz, which displays superb absorption efficiency in both the C band and X band. The phthalocyanine-mediated dielectric-magnetic synergy endows the nanocomposite with enhanced impedance matching and multiple dissipation pathways. This study demonstrates a convenient strategy for the rational design of low-frequency EMW absorbers with high-efficiency absorption.

Real-time monitoring of cellular Ca2+ efflux with renewable graphene field effect transistor biosensor

Calcium ion (Ca2+) is not only an intracellular second messenger, but also functions as an important messenger outside cells for intercellular communications. It is significant to develop a tool for dynamically probing the release of Ca2+ in the extracellular microenvironment. Here we present a photocatalysis-induced renewable reduced graphene oxide nanosheet field effect transistor (rGON-FET) biosensor for real-time monitoring of extracellular Ca2+ release. The biosensing channel was assembled layer-by-layer with reduced graphene oxide nanosheet (rGON) and titanium dioxide-reduced graphene oxide composites (TiO2-RGO) as a sandwich conducting nanostructure. Importantly, this biosensor was capable of measuring the dynamic extracellular Ca2+ release in a real time manner after immobilization of Ca2+ specific binding molecule Fluo 4-AM on the channel interface, particularly within the nano-confined space between the sensor surface and cell bottom. It was found that this biosensor could achieve a detection limit down to 100 pM in phosphate-buffered saline (PBS), and 1 nM in fetal bovine serum (FBS), respectively. Such a functional nanosensor also showed high selectivity to Ca2+ in the presence of excessive amounts of other metal ions. By using photo-responsive self-cleaning TiO2-based nanointerface, this renewable biosensor could be recycled to detect the exocytotic Ca2+ repeatedly. These advantages allow the rGON-FET biosensor to be further used in environmentally and clinically related metal ions detection.

The Anticancer Efficacy of Thiourea-Mediated Reduced Graphene Oxide Nanosheets against Human Colon Cancer Cells (HT-29).

The current research focuses on the fabrication of water-soluble, reduced graphene oxide (rGO) employing thiourea (T) using a simple cost-effective method, and subsequently examining its anticancer characteristics. The cytotoxicity caused by graphene oxide (GO) and T-rGO is investigated in detail. Biological results reveal a concentration-dependent toxicity of GO and T-rGO in human colon cancer cells HT-29. A decrease in cell viability alongside DNA fragmentation is observed. Flow cytometry analysis confirms the cytotoxic effects. The novelty in this work is the use of raw graphite powder, and oxidants such as KMNO4, NaNO3, and 98 percent H2SO4 to produce graphene oxide by a modified Hummers method. This study demonstrates a simple and affordable procedure for utilising thiourea to fabricate a water-soluble reduced graphene oxide, which will be useful in a variety of biomedical applications.

Ultrsonication mediated Iron-doped reduced graphene oxide nano-sheets exhibiting unique physico-chemical properties and biomedical applications

In this study, reduced graphene oxide nanosheets have been synthesised using hummers method in the laboratory conditions. Lateral thickness came to be ∼8–10 nm thickness profile. Crystallographical properties of the reduced graphene oxide sheets were achieved from the different X-Ray Diffraction (XRD) studies, thereby achieving (002) for reduced graphene oxide, when compared to (001) (hkl) planes for intermediate Graphitic peak, respectively. The as-formed diffraction planes signifies the formation of diffraction planes at ∼25° diffraction angle for effective formation of Reduced graphene oxide, resulted from the reduction and exfoliation from pure Graphitic structure. The nano-composites of the as-prepared Fe-Doped Reduced graphene oxide sheets has been analysed, employing the Fourier-Transform Infra-Red (FT-IR) spectroscopy approach. The elucidation of the different molecular vibrational aspects of the transitional d-block metal Fe doped Reduced graphene oxide sheets have been studied for the justification of Fe-incorporated Reduced graphene oxide sheets. Further, the micrographical analyses of the Fe-Doped different layered RGO sheets has been evaluated by High-Resolution Transmission Electron Microscopy (HR-TEM) with their respective EDAX analyses exhibting an average diameter of the as-formed composites ∼26.78 nm. Finally, the biophysical aspects of the as-prepared nano-composites were explored into the prokaryotic model organism of Gram –ve (Escherichia coli) and Gram + ve (Staphylococcus aureus) bacterium species. It is perceived that, uncovering and evaluating the underlying interaction(s) taking place between the magnetic based materials at the nano-scale posessing magnetically transistional metallic attributes within the biological organisms, would help to pave the way in unveiling the quantum-mechanical and thermodynamical attributes taking place at the nano-scale rate and kinetics of the material-bio interface.

In-situ construction of nano-sized Ni-NiO-MoO2 heterostructures on holey reduced graphene oxide nanosheets as high-capacity lithium-ion battery anodes

Transition metal oxide anodes for lithium-ion batteries (LIBs) have evoked widespread concern by reason of their high theoretical capacity, abundance, and diversity. Nevertheless, they suffer from severe volume expansion/contraction and slow reaction kinetics during cycling, resulting in poor electrochemical lithium storage performance. Herein, we ingeniously design a unique multi-component composite with Ni-NiO-MoO2 heterostructure nanoparticles in-situ dispersed on holey reduced graphene oxide (rGO) nanosheets using a facile self-sacrificed MOFs template method. The integration of Ni-NiO-MoO2 heterostructure nanoparticles and well-conductive rGO nanosheets with unique nanoholes can collaborate the inherent properties of each component to improve the reaction kinetics and synergistically enhance the lithium storage property. Thereby, the Ni-NiO-MoO2/rGO composite as a LIB anode exhibits outstanding cycling performance with a high reversible capacity (910 mAh g−1 after 220 cycles at 500 mA g−1) as well as excellent rate capability maintaining the great capacity retention of 534 mAh g−1 at 3000 mA g−1. This research offers a vital inspiration for designing and fabricating multi-component metal oxide-based composite anode materials for high-performance LIBs.

CuO–Fe2O3 nanoparticles embedded onto reduced graphene oxide nanosheets: a high-performance nanocomposite anode for Li-ion battery

CuO–Fe2O3 nanoparticles embedded onto reduced graphene oxide nanosheets: a high-performance nanocomposite anode for Li-ion battery

Effects of Ni-decorated reduced graphene oxide nanosheets on the microstructural evolution and mechanical properties of Sn-3.0Ag-0.5Cu composite solders

Introducing foreign reinforcements into solder joints has been demonstrated to be beneficial to promoting the soldering reliability. In this work, Ni-decorated reduced graphene oxide (Ni-RGO) nanosheets as foreign reinforcements were prepared through the in-situ thermal decomposition of Ni-glycolate@RGO complexes. xNi-RGO/SAC305 composite solders (x = 0, 0.01, 0.03, 0.05, 0.07, 0.1 wt%) were fabricated by the powder metallurgy method. The results showed that Ni nanoparticles were finely and evenly anchored on both sides of RGO nanosheets. The grain size in xNi-RGO/SAC305 composite solders was significantly refined, while the thickness of the interfacial intermetallic compounds (IMCs) decreased with increasing of Ni-RGO content. The average tensile strength of Cu/(Ni-RGO/SAC305)/Cu solder joints reached 43.0 MPa (18.1% higher than that of the plain SAC305 solder joints) when the amount of Ni-RGO addition reached 0.03 wt%, in which the crack initiation formed occurred in the soldering seam zone. The crack initiated in the micropores between the copper parent metal and composite solder when the content of Ni-RGO nanosheets was above 0.05 wt%, which may due to the agglomerating of submicron-sized Ni-RGO at the interface. These results suggest that traces of Ni-RGO nanosheets (0.03 wt%) can efficiently improve the interfacial bonding strength and solderability of the Cu/(Ni-RGO/SAC305)/Cu solder joint.

Silver-substituted cobalt zeolite imidazole framework on reduced graphene oxide nanosheets as a novel electrode for supercapacitors

Although metal-organic frameworks demonstrate enhanced surface area, incredible porosity, and a well-controlled structure, they exhibit low conductivity, limiting their use in energy storage devices. In this work, we incorporated different mass loadings of silver, the metal with the highest conductivity in the zeolitic imidazolate framework-67 (ZIF-67) to enhance the electrochemical performance of their composites. The synthesized composites were extensively characterized using various techniques, and the electrochemical characterization of the constructed electrodes in 6 M KOH was performed using a two-electrode Swagelok cell. The results showed that the composite (ZIF-67.Agx=10/RGO) formed an efficient bimetallic structure and performs optimally with a specific capacitance (Cs) of 375 F/g at 5 mV s−1 and the smallest equivalent series resistance. The electrode material exhibited promising cycling stability over 2000 cycles reaching 97 % at 2 A g−1. Moreover, its energy density reached 46.388 Wh/kg along with a power density of 199.7 W/kg. Furthermore, it possessed the maximum specific surface area with all fabricated active material composite electrodes, reaching 1105 m2/g. The proposed composite can be used in energy storage applications and the conductivity will be further enhanced by co-doping.

Superparamagnetic Iron Oxide Nanoparticles (SPIONs) and Reduced Graphene Oxide (RGO) Based Nanocomposites Prepared by Low-Temperature Route and Their Anticancer Properties

In this work, a facile low temperature solution route was reported for the preparation of monodisperse Fe3O4 nanoparticles and their reduced graphene oxide (RGO) based nanocomposites and used as anticancer agents. X-ray diffraction spectroscopy XRD and Raman studies revealed the high crystalline nature of the Fe3O4 nanoparticles and the presence of characteristic peaks of RGO in Fe3O4/RGO nanocomposites. Transmission electron microscopy (TEM) micrographs showed the morphology of the RGO nanosheets decorated by Fe3O4 nanoparticles with sizes ranging from 10–15 nm. High resolution (HR)-TEM study revealed the formation of Fe3O4/RGO nanocomposites with the interplanar spacing corresponding to the (311) plane of Fe3O4. The anti-cancer properties of Fe3O4/RGO nanocomposites against A549 cells were investigated using MTT, NRU assay, morphology of cells, and ROS generation analyses and compared with the pure Fe3O4 nanoparticles. In comparison between both the pure Fe3O4 and Fe3O4/RGO nanocomposites, more damage to the A549 cells resulted from the nanocomposites at a similar concentration of 100 μg/ml. The cell viability test showed that 36% cell viability was observed at a concentration of 100 μg/ml for Fe3O4/RGO nanocomposites. Additionally, the percentage of ROS generation for Fe3O4/RGO nanocomposites was higher than that of Fe3O4 at a concentration of 100 μg/ml. These results suggested that the as-synthesized nanocomposites might be a potential candidate for future anticancer agents.

In-situ directly anchored CoMoS4 particles on reduced graphene oxide nanosheets for the high-efficiency asymmetric supercapacitor

The well-designed CoMoS4/reduced graphene oxide (RGO) composite was directly synthesized by a simple one-step hydrothermal method, in virtue of the uniformly-distributed oxygen-containing functional groups on the precursor graphene oxide (GO) surface. As expected, the optimized CoMoS4/RGO exhibits the high specific capacity of 123 mAh/g at 1 A/g, about 152% higher than that of pure CoMoS4. The reason is as follows: (1) the structure with no serious aggregation can be favor of rapid electrolyte ion transport process; (2) the RGO phase cannot only provide the high specific surface area, moderate conductivity and electrochemical double layer capacitance from the Π conjugated carbon skeleton, but also contribute to some extra Faradaic redox capacitance from a few oxygen-containing functional groups. As for practical application, the fabricated CoMoS4/RGO//AC asymmetric supercapacitor can deliver the good energy storage performances, such as the high energy density of 59 Wh/kg at 1125 W/kg (almost superior to the reported CoMoS4 based asymmetric supercapacitor devices to our best knowledge), especially for the good cycle stability with 99.3% capacity retention after 6000 cycles. Therefore, this work can provide a feasible strategy to improve the supercapacitor performances of CoMoS4.

Photocatalytic degradation of antibiotic drug and dye pollutants under visible-light irradiation by reduced graphene oxide decorated MoO3/TiO2 nanocomposite

This study explored the effect of reduced graphene oxide (RGO) amount (1, 3, and 5 wt%) loading on the MoO3/TiO2 nanocomposite (Gr1/MoO3/TiO2 NCs, Gr3/MoO3/TiO2 NCs, and Gr5/MoO3/TiO2 NCs) for their photocatalytic activity against the Tetracycline (TC) antibiotic drug and Rhodamine B (RhB) dye under visible light illumination and compared it with the MoO3/TiO2 nanocomposite. Crystallite sizes of MoO3/TiO2 NCs, Gr1/MoO3/TiO2 NCs, Gr3/MoO3/TiO2 NCs, and Gr5/MoO3/TiO2 NCs are 17.69 nm, 16.24 nm, 12.64 nm, and 11.74 nm, respectively, with energy band gaps of 2.72 eV, 2.59 eV, 2.49 eV, and 2.38 eV correspondingly. The photocatalytic performance of the nanocomposites was revealed to be highly affected by the weight ratio of RGO on MoO3–TiO2. The results showed that about 98% of RhB and 94% of TC drug were photodegraded under visible light irradiation during the 60 min and 80 min respectively. RhB and TC drug photocatalysis degradation showed pseudo-first-order reaction kinetics, with order rate constants of 0.06435 min−1 and 0.0351 min−1, respectively. By electrostatic interactions, the stacked MoO3 being bound to the surface of TiO2 nanoparticles and concurrently anchored onto graphene nanosheets through π–π stacking. In addition, the inclusion of reduced graphene oxide nanosheets was shown to enhance photocatalytic activity. The mechanism was also portrayed: the synergetic (interfacial) interaction of the graphene sheets and the MoO3/TiO2 was responsible for the excellent photo-degradation impact of the RhB dye and the TC drug pollutants through the Gr/MoO3/TiO2. Furthermore, the MoO3/TiO2 has been used as a migration vehicle for the visible light carrier, while a high surface area and the number of active sites of the reduced graphene sheet enhanced the photocatalytic activity.