Crumpled Graphene Oxide Research Articles

Structural Modification Strategy for Enhancing Electrochemical Performance of Electrodes Under High Current Cycling and First Principle Computational Research for Electrode Materials

Recently, there has been significant interest in advancing lithium-ion battery technology due to its widespread use in various applications. Our research delves into this domain, focusing on enhancing the electrochemical properties of batteries through structural modification of electrode materials. Our work demonstrates the significant enhancements of electrochemical performance under high current cycling using structurally modified electrode materials . In first work, crumpled graphene oxide anode proves to be an effective strategy for enhancing its electrochemical properties, attributed to its advantageous crumpled morphology. This morphology allows for improved electrode stability and easier access for lithium ions, enabling them to interact with its larger specific surface area. In second work, we describe enhanced the drawback of reduced electrochemical performance during high-rate cycles by synthesizing multidimensional LFP-based carbon composite. The lithium ion diffusivity and electrode stability of the prepared composite are significantly improved in charging and discharging cycles by introducing graphene quantum dots alongside CNTs, exhibiting superior electrochemical properties even at high current densities. In third work, density functional theory simulation is employed for demonstrating the enhanced electrochemical properties of prepared electrodes by exploring their properties. Our research provides insights into electrode material design as an effective approach to enhancing the electrochemical properties of lithium-ion batteries.Acknowledgement:This work was supported by the National Research Foundation of Korea (NRF-2021R1A2C1008272). This work was supported by Ministry of Trade, Industry and Energy, KEIT, under the project title"International standard development of evaluation methods for nano-carbon-based high-performance supercapacitors for electric vehicles" (project # 20016144).

The Preparation of Crumpled Graphene Oxide Balls and Research in Tribological Properties.

In this study, crumpled graphene oxide balls (CGBs) were prepared via capillary compression using a rapidly evaporating aerosol droplet method. The CGBs were observed using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The size distributions of crumpled particles were obtained using a laser nanometer particle size analyzer (DLS). The dispersibility of the water and the ionic liquid (IL) was tested by ultrasonic dispersion. The tribological properties of water or ionic liquids containing crumpled graphene oxide ball additives (W/IL-CGB) were tested by a reciprocating friction tester and compared with water/ionic liquids with graphene oxide. The morphology of the wear scar was observed by a three-dimensional optical microscope and its lubrication mechanism was analyzed. The results show that the CGBs were successfully prepared by rapid evaporation of aerosol droplets, and the obtained CGBs were crumpled paper spheres. The CGBs had good water dispersion and ionic liquid dispersion, and IL-CGB has excellent anti-friction and anti-wear effects on steel-steel friction pairs. During the friction process, the CGB was adsorbed at the interface of the steel-steel friction pair to form a protective layer, which avoids the direct contact of the friction pair, thereby reducing friction and wear.

Metal oxide encapsulated by 3D graphene oxide creates a nanocomposite with enhanced organic adsorption in aqueous solution.

The presence of organic contaminants (OCs) in aquatic systems is a threat to ecological and human health. Adsorption by graphene-based adsorbent is a promising technique for OC removal and we previously fabricated crumpled graphene balls (CGBs), via a novel nano-spray drying technique, which show robust adsorptive performance. Yet, since CGBs contain non-accessible surface area due to 2D graphene stacking, the goal of this research was to investigate the efficacy of maximizing the accessible CGB surface by synthesizing a nanocomposite composed of metal oxide nanoparticles encapsulated by crumpled graphene oxide (MGC). The metal oxides reduce graphene oxide stacking, expand the internal adsorptive surface area, and boost the adsorptive capacity of the MGC. MGC (fumed SiO2 or SiO2) exhibit an enhanced Langmuir adsorption capacity (qm, normalized by the % carbon) for an OC model, methylene blue (MB), achieving improvements of 60-86% compared to CGB, 3-4 fold compared to powder activated carbon (PAC) and 6-7 fold compared to granular activated carbon (GAC). MGCs display rapid adsorption reaching equilibrium after 9-12min of contact and remaining stable in wastewater effluent /surface water. A cost-efficiency comparison reveals MGCs achieve one ton of MB removal at similar or lower material costs than that of PAC/GAC.

Crumpled graphene oxide for enhanced room temperature gas sensing: understanding the critical roles of surface morphology and functionalization

This work fundamentally explores graphene oxide morphology and functionality with regard to room temperature gas sensing performance.

Facile Synthesis of Crumpled Graphene Oxide and Its Outstanding Electrochemical Performance as an Anode in Lithium Ion Batteries

Facile Synthesis of Crumpled Graphene Oxide and Its Outstanding Electrochemical Performance as an Anode in Lithium Ion Batteries

Anchoring the TiO2@crumpled graphene oxide core–shell sphere onto electrospun polymer fibrous membrane for the fast separation of multi-component pollutant-oil–water emulsion

Membrane separation technology offers the unique advantages in oily wastewater treatment. However, the oily wastewater in petrochemical industry often contains oil emulsions and soluble organic pollutants, which pose great obstacles to membrane materials. Herein, to address the aforementioned challenges, a multifunctional fibrous composite membrane (FCM) was prepared by simple spraying of three-dimensional (3D) TiO2@crumpled graphene oxide (GO) core–shell sphere onto electrospun poly (arylene ether nitrile) (PEN) porous support. In the hierarchical skin layer of composite membrane, the TiO2 nanoparticles were anchored onto 3D crumpled graphene oxide sphere surface assisted by the mussel-inspired dopamine coating, which further triggered the formation of chemical cross-linking networks and hydrogen bond interaction with tannic acid. Such rational design not only ensured the structure stability of the functional layer, but also achieved the extraordinary versatility and high separation efficiency compared the conventional two-dimensional GO stacked lamellar membranes. Due to the super-hydrophilicity/underwater hydrophobic feature, low oil adhesion, and well-regulated water channels, the GO@TiO2/PEN FCM exhibited superior permeance for various surfactant free (4830–5160 L·m−2·h−1) and stabilized oil-in-water emulsions (3142–3514 L·m−2·h−1) while keeping stable rejection rate over 99%. Moreover, the combination of TiO2 nanoparticles and GO endowed the FCM with synergistically enhanced photocatalytic degradation performance for the soluble organics. Under visible light irradiation, the degradation rate of methylene blue (MeB) and crystal violet (CV) could reach 90.8% and 92.5% in 60 min, respectively. Therefore, combination of high permeability and efficient photocatalytic degradation of the soluble organics enable the fibrous composite membrane to realize the fast separation of multi-component pollutant-oil–water emulsion.

Macroporous vanadium dioxide–reduced graphene oxide microspheres: Cathode material with enhanced electrochemical kinetics for aqueous zinc-ion batteries

Aqueous zinc-ion batteries are being extensively investigated owing to their safe operating conditions. Therefore, the search for cathode materials with optimum composition and nanostructure that enable high zinc-ion storage performance is underway. This study introduces a procedure for the formation of vanadium dioxide-nanoflake-reduced graphene oxide composite (P-VO2@rGO) microspheres with open pores through spray pyrolysis. Spherical cathode materials are formed by spray pyrolysis through the addition of polystyrene nanobeads and graphene oxide nanosheets in the spray solution. This enabled the formation of porous and crumpled graphene oxide microspheres, wherein thin VO2 nanoflakes are anchored. As a cathode for zinc-ion batteries, P-VO2@rGO exhibits a high rate capability (159 mA h g−1; current density = 5.0 A g−1) and stable cycle performance for the 300 cycles at 1.0 A g−1. To discern the synergistic effect of the reduced graphene oxide (rGO) and 3D-porous structure with a small crystal size on the zinc-ion storage, control samples (VO2-rGO composite and porous VO2 microspheres) are synthesized and tested as cathodes for zinc-ion batteries. The synergistic effect of compositing rGO and introducing porous structure with small crystal size enables high reversible capacity and enhances electrochemical kinetics of the electrode.

Flexible highly-sensitive humidity sensor based on CGO/SMPLAF for wearable human skin humidity detection

Conventional humidity sensors have poor flexibility and low sensitivity, which makes them difficult for wearable electronic device applications. This study aims to fabricate a flexible, high-sensitivity and breathable humidity sensor for skin humidity monitoring. The sensor includes two parts, i.e., shape memory polylactic acid fiber (SMPLAF) as the substrate and crumpled graphene oxide (CGO) membrane as the top humidity-sensitive layer. SMPLAF was firstly stretched and then heated to restore its original shape to obtain the CGO membrane. The unique crumpled morphology of CGO membrane provides a large specific surface area and high capillary force, which facilitates the rapid exchange of water molecules between the sensing CGO membrane and the external environment. Accordingly, the sensor exhibits excellent humidity sensitivity, fast response time (<5 s) and long term stability (15 days). Moreover, the CGO-based sensor demonstrates excellent flexibility. Bent at 120°, the response almost unchanged, whereas the response of the sensor without CGO decreased from 0.89 to 0.66. Though the sensor has the disadvantage of unstable performance at high RH, it could be overcome by controlling the wavelength of the crumpled structure of CGO. Due to the above superior properties, the sensor shows promising potentials for human breath monitoring and skin humidity test.

TiO2 (Core)/Crumpled Graphene Oxide (Shell) Nanocomposites Show Enhanced Photodegradation of Carbamazepine.

The presence of pharmaceuticals and personal care products (PPCPs) in aquatic systems is a serious threat to human and ecological health. The photocatalytic degradation of PPCPs via titanium oxide (TiO2) is a well-researched potential solution, but its efficacy is limited by a variety of environmental conditions, such as the presence of natural organic macromolecules (NOM). In this study, we investigate the synthesis and performance of a novel photoreactive composite: a three-dimensional (3D) core (TiO2)-shell (crumpled graphene oxide) composite (TiGC) used as a powerful tool for PPCP removal and degradation in complex aqueous environments. TiGC exhibited a high adsorption capacity (maximum capacity 11.2 mg/g, 100 times larger than bare TiO2) and a 30% enhancement of photodegradation (compared to bare TiO2) in experiments with a persistent PPCP model, carbamazepine (CBZ). Furthermore, the TiGC performance was tested under various conditions of NOM concentration, light intensity, CBZ initial concentration, and multiple cycles of CBZ addition, in order to illustrate that TiGC performance is stable over a range of field conditions (including NOM). The enhanced and stable performance of TiCG to adsorb and degrade CBZ in water extends from its core-shell composite nanostructure: the crumpled graphene oxide shell provides an adsorptive surface that favors CBZ sorption over NOM, and optical and electronic interactions between TiO2 and graphene oxide result in higher hydroxyl radical (•OH) yields than bare TiO2.

Crumpled graphene oxide/spinel cobalt oxide composite based high performance supercapacitive energy storage device

Crumpled graphene oxide (cGO) was synthesized using a facile liquid phase exfoliation technique mediated by OHˉ cutter; followed by the synthesis of cGO/Co3O4 composite through hydrothermal route involving the as-synthesized cGO and cobalt salt precursors. Co3O4 is a mixed oxide of cobalt that exhibits good redox and charge cycling attributes owing to the presence of Co(II) and Co(III) oxidation states within it. This report includes thorough investigation on the electrochemical and charge storage properties of the fabricated electrodes using cyclic voltammetry, charge – discharge and impedance analyses, and also by endurance test. The report also describes detailed evaluation of the structural properties of the products (cGO and cGO/Co3O4 composites). Two sets of prototype ‘symmetric’ supercapacitors were fabricated using aqueous and gel KOH based electrolytes that successfully lit up LED and run a DC motor. The gel KOH electrolyte based device showed best performance and yielded 44 Wh/Kg specific energy and 1202 W/Kg specific power. The results are quite promising which open up a new avenue for using cGO/Co3O4 composite as a low cost alternative for conventional and costly carbon nanomaterial based supercapacitors.

Crumpled graphene balls adsorb micropollutants from water selectively and rapidly

Thousands of anthropogenic materials (e.g., micropollutants, MPs) are discharged to surface and groundwaters daily and their wide distribution potentially threatens ecological and human health. Granular activated carbon (GAC) is a widely used adsorbent to remove MPs, but with several deficiencies such as slow adsorption kinetics and hindered performance by natural organic macromolecules (NOM). Here, we detail the synthesis of a novel adsorbent, three-dimensional (3D), stacking-resistant, crumpled graphene oxide balls (CGBs) and their adsorbent properties by using eight persistent MPs under relevant environmental conditions. CGBs displayed 4–8 times greater adsorption capacity than GAC for seven of the eight MPs on a surface area equivalent basis. Kinetic experiments show that seven of eight MPs in a mixture reach >90 % removal efficiency after 15 min contact time (compared to 5–10 % removal of GAC). CGB adsorption performance was also tested as a function of varying NOM concentration, with other realistic environmental conditions of pH, ionic strength, water hardness, and alkalinity, to demonstrate that CGB adsorption of MPs is not adversely affected by NOM even at high concentrations and is stable over a range of field conditions. These findings demonstrate that CGBs are potentially a powerful adsorbent for micropollutant removal in complex aqueous environments.

N, B co-doped and Crumpled Graphene Oxide Pseudocapacitive Electrode for High Energy Supercapacitor

N, B co-doped graphene oxide (NB-GO) establishes a novel electronic structure owing to the distinctive B and N coupling significantly differs from the conventional electrical double-layer mechanism of carbon-based electrodes. The remarkable electrochemical properties of NB-GO are owed by the high content of N (4.61 at.%), and B (4.41 at.%) shrinkages charge transfer resistance, and inflation of the surface polarity as well as pseudocapacitive electro-active sites. The new motifs B-N, C-N, and C-B-N contribute affluent and stable redox-active sites for enhanced pseudocapacitive properties of NB-GO compared to that of the un-doped GO and B doped GO (B-GO), including excellent specific capacitance (885 Fg−1), outstanding rate capability (525 Fg−1 at 10 Ag−1) and good cycle stability (77.8%) retained till 10,000 continuous cycles. NB-GO//RGO asymmetric supercapacitor (ASC) demonstrate an affordable energy density of 23.23 Wh/kg consistent with a massive power density of 872 W/kg with 80% capacitance retention after 10,000 cycles. Therefore, a facile hydrothermal route will be a successful method for synthesizing NB-GO as an alternative for metal oxide/sulfide and polymer-based pseudocapacitive electrode materials for supercapacitor applications.

Mechanics of nanoscale crumpled graphene measured by Atomic Force Microscopy

Crumpling profoundly alters the chemical, electrical, mechanical and tribological properties of 2D materials. Structural deformations at these scales can correlate to the local chemical composition, thereby providing a novel method to tune their properties. In order to leverage the unique characteristics of these compact, high surface area structures, it is crucial to understand the mechanical behavior of crumples at the nanoscale and the effect of chemical composition on the crumpling mechanics. Here, we explore the mechanics of crumpled graphene and graphene oxide nanostructures through force-indentation routines using Atomic Force Microscopy. Crumpled graphene and crumpled graphene oxide show a multi-regime power law force deflection response with exponents ranging between 1.2–2.5. Pushing on the crumpled nano-structures induces both reversible and irreversible energy dissipation, which can be observed through changes in the hysteresis between the loading and unloading curves. Describing folding as a structural transformation passing through a metastable transition state with a finite energy barrier, the total energy imparted during force-indentation routines can be quantitatively related to the energy required to bend monolayer graphene. We also demonstrate that the chemical composition of the crumples can strongly influence the energy dissipation, where crumpled graphene consistently dissipated a smaller amount of energy irreversibly compared to crumpled graphene oxide.

Auxetic graphene oxide-porous foam for acoustic wave and shock energy dissipation

Auxetic cellular structures have garnered huge research interest as a candidate for energy absorption due to their appealing features, including extremely high indentation resistance and fracture resistance. However, auxetic foams reported so far typically can only sustain a very limited loading force and impact with a counter-intuitive behavior. Here, we report a highly efficient sound and shock absorber based on three-dimensional (3D) auxetic foam with two-dimensional (2D) wrinkled graphene oxide. Compared with pure polyurethane foam, the auxetic heterostructured polyurethane foam interconnected with 2D corrugated graphene oxide shows a sound absorbing capacity of 99.7% at a frequency of 2,236 Hz and a shock energy absorbing time of 189% during the impact loading. The synergistic effects between 3D auxetic foam and 2D wrinkled graphene oxide result in stable compressive cycling performance, more indentation resistance, and more energy dissipation during local impact loads. This 3D engineered auxetic porous structure with 2D crumpled graphene oxide provides a new and cost-effective strategy to effectively absorb acoustic and shock energy.

High-throughput and Multimodal Separation of Microbeads Using Cyclical Induced-charge Electro-osmotic Vortices and Its Application in Size Fractionation of Crumpled Graphene Oxide Balls

Crumpled graphene oxide (CGO) balls are new 3D applied materials, which present good potential in the development of energy storage and conversion devices for the advantages of high surface areas and resistant to aggregation. Utilizing ready-made CGO balls with defined sizes to synthesize desired materials or modify existing components, if achieved, we may make the functions and properties of the final products more controllable and programmable. However, acquiring uniform-size CGO particles still remains under challenge now, because uniform-size pristine graphene oxide is difficult to obtain and the size of CGO balls is sensitive to many parameters during the synthesis. An alternative potential solution, classifying the synthetized CGO balls to obtain uniform-size CGO balls may ingeniously circumvent above tricky issue. Here we designed tilted-angle ridge floating electrode sequence (TARFES) to actuate cyclical asymmetrical ICEO (AICEO) vortices to achieve particle separation and augment the throughput capability (105 particles/h), overcoming the limitation of existing vortex-based separation criteria. We firstly conducted simulations to identify the optimum configuration of TARFES. According to spatial features of cyclic AICEO vortices, two separation modes were developed. We separated silica and polymethyl methacrylate (PMMA) microbeads to validate the capability of the first separation mode, and studied the effects of voltage and flow speed on the separation results, obtaining 97.3% separation efficiency. We then separated PMMA microbeads and yeast cells with 93.1% separation efficiency to evidence the second separation mode. Also, we accomplished the simultaneous separation of multiple particles. Depending on characterization of CGO balls, the second separation mode was successfully engineered to realize size fractionation of CGO balls in continuous flow, yielding clear separation. Finally, we also modulated the voltage input to isolate nanoscale CGO balls from the background. This operative separation technique offers a unique route to acquire uniform-size CGO balls with potential applications in the fabrications of batteries and ultracapacitors.

Mechanism of Controlled Release of Vancomycin from Crumpled Graphene Oxides.

The physical and chemical interactions with vancomycin (VAN) were accessed between graphene oxide (GO) and crumpled graphene oxide (CGO) to present the possible loading and release mechanisms. The improved hydrophilicity and surface charge were found on CGO through water contact angle and ζ-potential measurements. Fourier transform infrared and X-ray photoelectron spectroscopies confirmed the attachment of VAN onto CGO or GO through π–π stacking and hydrogen bonding. Both CGO–VAN and GO–VAN drug complexes showed pH-controlled release property. The high VAN loading and delayed release in CGO–VAN system were mainly due to the crumpled morphology.

Graphene oxides as nanofillers in polysulfone ultrafiltration membranes: Shape matters

While a number of graphene oxide (GO) materials have been evaluated as nanofillers in ultrafiltration membranes, there remain outstanding questions regarding GO material properties relating to membrane structure(s) and eventual performance (i.e. structure-performance relationships). In this work, we synthesize, apply, and evaluate GO analog materials of different shape, flat GO and crumpled GO (CGO), as nanoscale fillers in polysulfone (PSF) ultrafiltration membranes. GO/CGO-PSF composite membranes were synthesized via phase inversion, characterized using both microscopic and spectroscopic techniques, and compared with respect to permeability, rejection, and anti-fouling properties. Experimental results show that graphene shape alone results in varied performance. Observed differences are attributed to the (more) effective dispersion/stability of CGO nanoparticles in solvent (NMP) as a result of shape effects, which lowers the tipping mass percentage after which the effect of viscosity increase outweighs that of hydrophilicity increase. Our results also suggest that the change(s) in membrane porosity is likely to be a more important factor compared to surface hydrophilicity in determining ultrafiltration membrane performance when graphene oxides are applied with these mass percentages. In addition to the effect of GO shape, this study also highlights the importance of nanoparticle dispersibility/stability in organic solvents when constructing the process-structure-performance relationships for nano-enabled ultrafiltration membranes synthesized via phase inversion.

Facile fabrication of crumpled graphene oxide nanosheets and its Platinum nanohybrids for high efficient catalytic activity

Crumpled graphene oxide nanosheets have drawn large attentions due to its compressibility and self-avoiding stacking as flat graphene sheets trend to aggregate and restack. Up to now, most of the synthesis approaches were relied on external substrates, such as elastic substrates or ultrasonic atomizer, and the crumpled structures were obtained in a solid state directly. Here we report a facile method to produce crumpled dispersive nanosheets in solution through general base-washing treatment by taking advantage of the amphipathy of GO nanosheets. With the dissociation of oxygen-functional groups on nanosheets in alkaline environment, highly water-soluble oxidative debris (OD) would fall off from the nanosheets due to the increase of electrostatic repulsions, and resulted in the crumple of the flat sheets, while the covalent oxygen-functional groups on the nanosheets were reserved. As a result, the nanosheets remained dispersible in solution, and could be used directly for surface modifications. Pt nanoparticles could be directly deposited onto both sides of the sheets through common nucleation and growth from precursor ions process. Compared with flat graphene-based hybrid, the catalytic performance of crumpled-graphene-Pt (CG-Pt) is more excellent and attractive, and corresponding apparent kinetic rate constant (kapp) of CG-Pt toward 4-nitrophenol reduction is enhanced by 2.7–4.6-fold. This study provides a new and facile way to fabricate crumpled nanosheets and demonstrates to be easy modified for various purpose.

Synthesis of mesoscale, crumpled, reduced graphene oxide roses by water-in-oil emulsion approach

Mesoscale crumpled graphene oxide roses (GO roses) were synthesized by using colloidal graphene oxide (GO) variants as precursors for a hybrid emulsification-rapid evaporation approach. This process produced rose-like, spherical, reduced mesostructures of colloidal GO sheets, with corrugated surfaces and particle sizes tunable in the range of ∼800 nm to 15 μm. Excellent reproducibility for particle size distribution is shown for each selected speed of homogenizer rotor among different sample batches. The morphology and chemical structure of these produced GO roses was investigated using electron microscopy and spectroscopy techniques. The proposed synthesis route provides control over particle size, morphology and chemical properties of the synthesized GO roses.

Decorated, crumpled graphene oxide assemblies for advanced imaging applications

Decorated, crumpled graphene oxide assemblies for advanced imaging applications