GO Layers Research Articles

Ultrafast Li+ Diffusion Kinetics of 2D Oxidized Phosphorus for Quasi-Solid-State Bendable Batteries with Exceptional Energy Densities

Phosphorus has drawn much attention for energy storage applications due to its high theoretical capacity while its surface is prone to oxidization, causing alterations of its physicochemical properties. Herein, we report a previously overlooked Li storage mechanism in the oxidized 2D black phosphorus/graphene oxide (BP/GO) heterostructure, where Li+ ions transport at an ultralow diffusion barrier of 80 meV and an ultrafast diffusion kinetics of 2.5 × 10–6 cm2 s–1 according to the ab initio molecular dynamics simulations. Furthermore, significant synergy arises when the 2D BP sheets chemically bind with GO layers, giving rise to an exceptional mechanical strength and flexibility of the BP/GO paper. The BP/GO composite anode sustains 500 stable cycles with Coulombic efficiencies as high as 99.6% in a Li ion half-cell. A quasi-solid-state, bendable Li-ion full-cell battery is assembled for the first time by using the BP/GO anode, a V2O5/CNT cathode, and a gel polymer electrolyte. It delivers simultaneously high gravimetric and volumetric energy densities of 389 Wh kg–1 and 498 Wh L–1, respectively, with a high retention rate of 92.3% even after 100 cycles of repeated folding and unfolding. The foregoing discovery makes the current flexible battery ideally suited for powering wearable electronics that require both high energy densities and mechanical robustness.

Graphene oxide/ZnO nanorods/graphene oxide sandwich structure: The origins and mechanisms of photoluminescence

In this paper, we present the structural and optical properties of Graphene oxide/ZnO nanorods/graphene oxide (GO/ZnO nanorods/GO) nanocomposites prepared via a hydrothermal method on Si (100) substrate. The X-ray diffraction measurements (XRD) confirm that the prepared samples are of hexagonal wurtzite structure with crystallite size around 50–60 nm. It was obvious from scanning electron microscopy (SEM) that by incorporating the ZnO nanorods between the inter-layer of GO confirmed the formation of sandwich-like nanocomposites structure. ZnO nanorods interaction with GO is displayed by the different vibrational frequencies in fourier transform infrared spectroscopy (FTIR). The UV–Vis spectrum reveals the strongest absorption was observed around 370 nm, while calculating optical band gap energy (Eg) of GO/ZnO NRs/GO was found to be 3.15 eV. The photoluminescence (PL) measurements indicates that the ZnO nanorods have a strong visible emission centered at 559 nm attributed to the presence of impurities in the form of oxygen vacancies After the nanorods were covered with GO layers, the PL intensity of the nanocomposite is quenched and shifted due to charge-transfer process. Consequently, the obtained results may lead to better performance for the optoelectronic applications.

Continuous ZIF-8/reduced graphene oxide nanocoating for ultrafast oil/water separation

Continuous ZIF-8/reduced graphene oxide (RGO) nanocoating is fabricated by growing ZIF-8 on RGO-coated polyurethane (PU) foam. Surface modification of PU foam can be easily achieved by immersing the PU foam in GO solution, followed by mild thermal treatment to turn the GO layer into RGO layer. Adhesion between polymer foam and ZIF-8 layer was enhanced by the inserted RGO layer because oxygen-containing groups of RGO could interact with Zn2+ precursor of ZIF-8 localizing the layer growth preferentially on the surface of RGO. The synergetic hydrophobic/oleophilic properties of RGO and ZIF-8 enable selective oil absorption of PU foam with an absorption capacity of 15–35 g/g depending on the viscosity of organic solvents. Most of all, the ZIF-8/RGO coated PU foam can filter organic solvent selectively via vacuum filtration, showing ultrafast hexane flux up to 800,000 Lm−2 h−1 and no water flux.

Microstructure and corrosion properties of zinc-graphene oxide composite coatings

Microstructure and corrosion properties of electrodeposited zinc-graphene oxide (Zn-GO) composite coatings and Zn-GO-Zn multilayer coating was investigated. Addition of GO enhanced the corrosion resistance of the composite coating. Microstructural characterization revealed that the enhancement in the corrosion resistance was due to GO induced significant reduction in Zn grains sizes which would facilitate formation of protective oxide layer. Microstructural characterization of exposed Zn-GO-Zn multilayer coatings revealed relatively lesser oxidation of Zn regions beneath the GO layer which further illustrated the role of impermeability of GO towards hindering the penetration of the electroactive media and thereby retarding the corrosion rate.

One-step facile synthesis of poly(N-vinylcarbazole)-polypyrrole/graphene oxide nanocomposites: enhanced solubility, thermal stability and good electrical conductivity

Poly (N-vinylcarbazole)-polypyrrole/graphene oxide (PNVC-Ppy/GO) nanocomposites have been successfully prepared by one-step chemical oxidative polymerization using ferric chloride hexahydrate in the presence of dodecyl benzene sulfonic acid. The composite formation, morphology and the crystallinity of the composite have been characterized by FTIR spectroscopy, FESEM, and XRD, respectively. The incorporation of graphene oxide into the PNVC-Ppy matrix induces interaction between graphene oxide and PNVC-Ppy via hydrogen bonding and π–π* stacking. This π–π* stacking between the GO layers and PNVC-Ppy produces longer conjugation length leading to a higher solubility in organic solvents and enhanced electron mobility. The information of conjugation chain length and charge transfer capacity at the interface of the composite has been obtained from the Raman spectroscopy and photolumincience spectroscopy. The improved thermal stability and electrical d.c. conductivity (0.123 S/cm) of the resulting PNVC-Ppy/GO composite compared to the PNVC–Ppy copolymer (0.08 S/cm) is attributed to the incorporation of graphene oxide in the composite.

Facile Surface Modification of Polyethylene Film via Spray-Assisted Layer-by-Layer Self-Assembly of Graphene Oxide for Oxygen Barrier Properties

The oxygen barrier properties are essential for the food packaging systems that preserve perishable food. In this research, the facile surface modification method for oxygen barrier properties is introduced by using spray assisted layer-by-layer (LbL) self-assembly. The nano-sized graphene oxide (GO−) multilayer films were developed and characterized. Positively charged amine-functionalized GO+ was synthesized using the negatively charged GO− dispersion, ethylenediamine, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide methiodide (EDC). Alternating layers of GO− and GO+ were deposited onto the flexible polyethylene (PE) substrate which has no intrinsic gas barrier properties. This method is able to modify surfaces which are challenging for the conventional dipping LbL method. The oxygen transmittance rate of coated PE film (3511.5 cc/m2·day) decreased significantly to 1091 cc/m2·day after a GO film with a thickness of only 60 nm was deposited. The light transmittance in the visible light range was not significantly decreased after coating of GO films, thus ensuring transparency for PE packaging applications.

Synthesis of nanogate structure in GO-ZnS sandwich material

Graphite Oxide (multi-layer) composite with other materials has a huge application in various field of science, due to its excellent and unique properties. Even though from past decade, immense research has been done by materials scientists in this field, but the chemistry is still not yet satisfactory. Here, in this work, through the discovery of Nanogate structure, we have reported for the first time the experimental results that enlightened the clear chemistry between the GO and ZnS which is further supported by the DFT calculations. This novel synthesis method led to the discovery of nanogate structure sandwiched between the GO layers. The nanogate formation also shows enhanced properties for various applications like photocatalytic activities, etc. Due to the nanogate formation, there might be a possibility of enormous generation of electrons on excitation of the composite materials, which can be a boom for various applications like photocatalysis, water splitting, solar cell, etc.

Multi-layer graphene oxide coated shape memory polyurethane for adjustable smart switches

Multi-layer graphene oxide (MLGO) coated shape memory polyurethane (MLGO@SMPU) with different layers was fabricated by multiple dipping for adjustable shape memory switching devices. The MLGO, which stacked together in parallel, evenly covered the surface of the SMPU. Stress strain testing indicated that the coating of GO improved the mechanical strength of these MLGO@SMPU composites in the stretching stage below the strain of approximately 6%. Adhesive force testing suggested that the first GO layer could adhere well to the SMPU surface, but the interaction force between GO layers was weak. The angle recovery ratio and time, bending recovery force, and angle fixity ratio of these MLGO@SMPU composites were evaluated using homemade evaluation apparatus. Results indicated that with the increase of GO layers from one to five layers, the MLGO@SMPU gave an angle recovery ratio reduced to 83.2%, recovery time decreased to 7.6 s, bending recovery force increased to 18.3 mN, and angle fixity ratio decreased to 83.3%. This novel and straightforward approach of dipping graphene oxide onto shape memory substrates for adjustable recovery ratio, time and force has the potential to be applied to smart switching devices including sensors and actuators.

Preparation of electrochemically reduced graphene oxide/bimetallic copper-platinum nanohybrid as counter electrode for fabrication of dye-sensitized solar cell

The present study was designed to deposit Cu-Pt bimetallic nanoparticles into an electrochemically reduced graphene oxide (ERGO) layer as an active material for counter electrode (CE) of a dye-sensitized solar cell (DSSC). At first, GO nanosheets were deposited on the surface of fluorine-doped tin oxide (FTO) electrode through an electrical field by an electrophoretic deposition method. Then, GO layer was converted to the ERGO by applying a negative potential vs. Ag|AgCl|KCl (saturated) to the electrode. Cu particles were electrochemically grown on the ERGO/FTO electrode surface by a chronoamperometric method from CuSO4 (1mM) aqueous solution during 50s. Then, Cu/ERG/FTO electrode was immersed into H2PtCl6 (2mM) solution to reduce PtIV ions into Pt0 species through a galvanic replacement process. The prepared electrodes were characterized using field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) and energy dispersive X-ray spectroscopy (EDS). The FE-SEM image showed that the ERGO surface was decorated with bimetallic Cu-Pt nanoparticles. Some properties of CE such as the ability for catalytic activity in reduction of triiodide to iodide (I3−/I−) and low charge transfer resistance were investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The EIS studies on various electrodes using I3−/I− redox couple demonstrated that a lowest charge transfer resistance value was obtained for the Cu-Pt/ERGO nanohybrid. Also, CV of the Cu-Pt/ERGO/FTO CE exhibited the highest current density and catalytic activity. The current density-voltage (J-V) test on the fabricated DSSCs showed the highest power conversion efficiency (PCE) of 4.30% for DSSC fabricated using Cu-Pt/ERGO/FTO CE.

Growth and Self-Assembly of Silicon⁻Silicon Carbide Nanoparticles into Hybrid Worm-Like Nanostructures at the Silicon Wafer Surface.

This work describes the growth of silicon–silicon carbide nanoparticles (Si–SiC) and their self-assembly into worm-like 1D hybrid nanostructures at the interface of graphene oxide/silicon wafer (GO/Si) under Ar atmosphere at 1000 °C. Depending on GO film thickness, spread silicon nanoparticles apparently develop on GO layers, or GO-embedded Si–SiC nanoparticles self-assembled into some-micrometers-long worm-like nanowires. It was found that the nanoarrays show that carbon–silicon-based nanowires (CSNW) are standing on the Si wafer. It was assumed that Si nanoparticles originated from melted Si at the Si wafer surface and GO-induced nucleation. Additionally, a mechanism for the formation of CSNW is proposed.

Ionic liquid induced electrostatic self-assemble of reduced graphene oxide for high-performance all-solid-state flexible symmetric supercapacitor

Flexible solid-state supercapacitors are arousing tremendous research enthusiasm in modern wearable and portable electronic equipment. Fabricating flexible electrode materials turns out to be a key challenge. Here, we developed a facile ionic liquid induced electrostatic self-assemble method to prepare bendable reduced graphene oxide (ILG). Due to electrostatic interaction between ionic liquid and graphene oxide, the ionic liquid can effectively prevent the aggregation of GO layers and protect partial O-containing functional groups at the same time. The IL plays great roles of a protector and stabilizer. The obtained ILG shows high specific capacitance (260 F g−1 at 0.5 A g−1), superior rate capability (62% from 0.5 to 100 A g−1) and outstanding energy density (9.03 W h kg−1 at 125 W kg−1) in 6 M KOH electrolyte. The constructed flexible symmetric all-solid-state supercapacitor also exhibits a specific capacitance of 195 F g−1 at 0.5 A g−1 and approximately 100% capacitance retention at different bending angels. The one-step approach might provide us with a new avenue for designing other flexible materials used in bendable devices.

Enhancement of broadband ultraviolet visible photodetection by boron nitride nanoparticles in bulk graphene oxide layer

A proposed boron nitride/graphene oxide (BN/GO) composite photodetector (PD) was prepared using a drop cast method for photodetection in the ultraviolet (UV) and visible light ranges. Morphology of the GO, distribution of BN nanoparticles and composition of B, N, C and O elements were confirmed by field emission scanning electron microscope (FESEM) analysis and energy dispersive x-ray (EDX) spectroscopy results. Raman scattering indicates high frequency intrinsic E2g vibrations at 1349 cm−1 and low intense peaks at 803 cm−1 from hexagonal BN (h-BN) structures in the bulk GO layer, while an overlap in the D and G bands at 1349 and 1581 cm−1 respectively indicates the presence of the GO layer. Excellent photoconduction of 380 and 405 nm UV sources and a 650 nm red laser source showed that the measured photocurrent is dependent on power regardless of the signal wavelength. Variations in sensitivity allow the device to be operated at selected direct current (DC) bias voltages, while high frequency modulation at 1000 Hz showed a profound rise and fall time about 13.6 and 245.6 μs respectively. Characteristics as self-powered PD was observed, has an enhancement about 3450% at its zero bias voltage.

Enhanced electrothermal efficiency of flexible graphene fabric Joule heaters with the aid of graphene oxide

Flexible fabric Joule heaters reflect a broad prospect due to their wearable substrate, low cost and easily compatibility to garment. In this paper, graphene-based fabric Joule heaters were fabricated with spraying coating method, the as-prepared fabrics possessed bilayer structure corresponding to the inner graphene/polyurethane layer and the outer graphene oxide layer respectively. The morphology and electrothermal performance of the fabric Joule heaters were accomplished by scanning electron microscopy and infrared camera. The outer graphene oxide could dramatically promote the electrothermal efficiency of the fabric Joule heaters with the steady-state temperature (162.6 °C) and the maximum heating rate (8.4 °C/s) under 10 V applied voltage, which was much higher than the heaters without GO layer with the steady-state temperature 70.1 °C and the maximum heating rate 2.61 °C/s. Therefore, the existence of GO layer was first demonstrated to observably enhance the electrothermal efficiency of flexible fabric Joule heaters.

Thin Nacre-Biomimetic Coating with Super-Anticorrosion Performance.

The rigorous organic and inorganic laminated structure of nacre has been developed by millions of years of biological evolution against various external impacts, including mechanical loadings and chemical attacks. Nacre-biomimetic materials have been recognized as an effective strategy to achieve high strength and toughness simultaneously. However, the understanding of nacre-like structure from the perspective of corrosion protection is still very limited. This work investigates the anticorrosion performance of nacre-biomimetic GO/epoxy (NBGE) coatings with alternating layers. Potentiodynamic polarization measurements indicated that the corrosion rate of steel protected by the NBGE coating with 5 layers of GO and 6 layers of epoxy (5NBGE) and a total thickness of 17 μm was 20 times slower than that of steel under the pure epoxy coating twice as thick in 3.5 wt % NaCl solution. Electrochemical impedance spectroscopy measurements revealed the importance and functions of the GO layers in NBGE coatings. The 5NBGE coating exhibited better performance than carbon-based nanoparticle/epoxy mixed coatings. The superior anticorrosion performance of the NB5G6E coating was supported by photographic observations, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chloride diffusion measurements. The strong cross-linking layer-by-layer structure of NBGE coatings was proved by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analyses. The anticorrosion mechanism of the NBGE coatings was interpreted by the mitigation of chemical reactions occurring at the steel-coating interface due to the restricted intrusion of O2, H2O, and Cl- through the reduced pores and defects by the intercalated GO layers in the coatings.

Effect of Graphene Oxide Thin Film on Growth and Electrochemical Performance of Hierarchical Zinc Sulfide Nanoweb for Supercapacitor Applications

AbstractSurface morphology induced electrical conductivity and specific surface area of a material play a significant role to facilitate electrochemical behavior for supercapacitor application. Therefore, the synthesis step for controlling such parameters becomes very imperative and challenging. Herein, a ZnS nanoweb is deposited directly onto Ni foam with a pre‐deposited thin layer of hydrothermally prepared graphene oxide. The structure and surface morphology of the deposited ZnS is observed using XRD and SEM, respectively. The electrical conductivity of the graphene oxide supported ZnS nanoweb, determined using the four probes method, is 100.15 S cm−1. The specific surface area is 104.42 m2 g−1 as determined by BET measurements. Pseudocapacitive behavior is monitored by cyclic voltammetry, and the excellent specific capacity of 3052 Fg−1 has been found at a scan rate of 2 mV s−1, while it is 2400.30 Fg−1 according the galvanostatic charge‐discharge profile at a current density of 3 mA cm−2. Both values are significantly higher than those measured for bare GO or ZnS layers. The energy and power densities of GO supported ZnS nanoweb are determined in a three electrode setup, are 120 Wh Kg−1 at 3 mA cm−2 and 4407.73 Wkg−1, respectively. In a symmetric two electrode setup, an energy density of 20.29 Wh Kg−1 at 2 mA cm−2 is observed. Hence, both symmetric and asymmetric measurements suggest that GO supported ZnS nanoweb can be applied as a suitable electrode for supercapacitors.

Multistimulus Responsive Actuator with GO and Carbon Nanotube/PDMS Bilayer Structure for Flexible and Smart Devices.

Smart devices with abilities of perceiving, processing, and responding are attracting more and more attentions due to the emerging development of artificial intelligent systems, especially in biomimetic and intelligent robotics fields. Designing a smart actuator with high flexibility and multistimulation responsive behaviors to simulate the movement of creatures, such as weight lifting, heavy objects carrying via simple materials, and structural design is highly demanded for the development of intelligent systems. Herein, a soft actuator that can produce reversible deformations under the control of light, thermal, and humidity is fabricated by combining high photothermal properties of CNT/PDMS layer with the natural hydrophilic GO layer. Due to the asymmetric double-layer structure, the novel bilayer membrane-based actuator showed different bending directions under photothermal and humidity stimulations, resulting in bidirectional controllable bending behaviors. In addition, the actuation behaviors can be well controlled by directionally aligning the graphene oxide onto carbon nanotube/PDMS layer. The actuator can be fabricated into a series of complex biomimetic devices, such as, simulated biomimetic fingers, smart "tweezers", humidity control switches, which has great potential applications in flexible robots, artificial muscles, and optical control medical devices.

Preparation of Nano-composites Membranes with Graphic Oxides and Polylactic Acid

Organic polymer materials were used as a layer of adhesive into the graphene sheet between the layers to enhance the interaction force between the nano-structure to achieve excellent mechanical properties and barrier properties. PLA with good flowability and easy processing was selected. The mechanical properties and barrier properties of the graphene-based composites were improved by the use of PLA for good flowability, making it easy to enter the GO layer as a binder. Three methods of preparation of GO / PLA homogeneous composite membranes were designed by vacuum filtration. The experimental results show that the injection of PLA as a molecular binder into the GO layer can effectively mimic the nano-structure, and enhance the intergranular force of the graphene molecules and the compatibility with the polymer matrix.

Graphene oxide hybrid poly(p-phenylene sulfide) nanofiltration membrane intercalated by bis(triethoxysilyl) ethane

Using organosilicon to crosslink and intercalate GO sheets, we made a hybrid GO layer on the surface of poly(p-phenylene sulfide) (PPS) microporous membrane support. A large number of oxygen-containing groups were introduced into the interlayer of GO layer, forming hydrophilic channels, more free interlayer space and nano-channels, which greatly enhanced the permeation and transmission of hydrophilic solvent. Furthermore, the introduced organosilicon species could improve the stability of PPS-GO@PB hybrid membranes. Water and ethanol were used as models to test the permeability of hybrid membranes, the results showed that the water and ethanol fluxes of GO@PB hybrid PPS membranes increased significantly. Especially, the water and ethanol fluxes of PPS-0.1GO@2.5PB membrane achieved 34.3 and 12.8 LMH under the pressure of 0.5 MPa. Four kinds of dyes were used as model pollutants to test the separation efficiency of the modified membrane, showing the high rejection of 99.2% (MB), 93.8% (MEB), 90.2% (BS) and 92.4% (RB), respectively. In the test of operation stability and solvent resistance, PPS-0.1GO@2.5PB membrane showed excellent stability and solvent resistance. These findings suggest that the as-prepared GO@PB hybrid PPS membrane will be great potential for utilization in the field of separation and purification of organic solvents and small molecules.

Graphene oxide-modified zinc anode for rechargeable aqueous batteries

Li-based batteries are intrinsically unsafe because of their use of flammable organic electrolyte. Great efforts are being made to develop solid electrolytes or safer alternative battery chemistries, among which Zn-based batteries stand out for their high energy density and good compatibility with aqueous electrolyte. Theoretically, Zn-air batteries have very high volumetric energy density, which is ∼85% of that of Li-S batteries. However, Zn anodes have poor cycling performance because of their passivation (insulating discharge product ZnO) and dissolution (soluble zinc species in alkaline electrolytes) problems.In this work, we overcome these problems by modifying Zn anode with graphene oxide (Zn@GO) by a facile solution casting method. The GO layers on the Zn surface can deliver electrons across insulating ZnO, slow down the Zn intermediates from dissolving into the electrolyte, and thereby enhance the utilization and rechargeability of Zn anodes. As a result, the Zn@GO anode containing only 1.92 wt% GO showed improved cycling performance compared to that of the unmodified Zn mesh. The accumulated areal discharge capacity of the Zn@GO anode is 128% of that of the unmodified Zn mesh. The Zn@GO anode reported here can potentially be paired with oxygen cathode to form safe high-energy rechargeable batteries, and be used in large scale applications, ranging from electric vehicles, to grid-scale energy storage. The surface modification method reported here can also potentially be applied to other high-capacity electrodes that undergo passivation or dissolution issues.

Effect of graphene oxide on the molecules of a sodium alginate–krill protein composite system and characterization of the system's composite fiber morphology and mechanical properties

ABSTRACTGraphene oxide (GO), sodium alginate (SA), and Antarctic krill protein (AKP) were blended to get functional fibers. These GO–SA–AKP composite fibers were obtained by conventional wet spinning with 5% calcium chloride as a coagulation solution. The intermolecular interactions of the GO–SA–AKP composite system were characterized by Fourier transform infrared spectroscopy. The morphology, crystallinity, thermal stability, and mechanical properties of the GO–SA–AKP composites were investigated with scanning electron microscopy, X‐ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. The results show that the number of GO layers decreased gradually during the process of wet spinning. The addition of GO promoted an increase in intramolecular hydrogen bonding and a decrease in intermolecular hydrogen bonding in the composite system. With increasing GO mass fraction, the intermolecular hydrogen‐bond content, crystallinity, breaking strength, and thermal stability in the composite system increased first and then decreased. At the same time, the mass fraction of GO and the draw ratio had significant effects on the surface morphologies of the composite fibers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46642.