Ultralight Graphene Research Articles

Emulsion-Based Multiscale Structural Design Realizes Lightweight and Superelastic Graphene Aerogels for Electromagnetic Interference Shielding.

Ultralight graphene aerogels with high electrical conductivity and superelasticity are demanded yet difficult to produce. A versatile emulsion-based approach is demonstrate to optimize multiscale structure of lightweight, elastic, and conductive graphene aerogels. By constructing Pickering emulsion using graphene oxide (GO), poly (amic acid) (PAA), and octadeyl amine (ODA), micron-level close-pore structure is realized while thermal shrinkage mismatch between GO and PAA creates numerous nanowrinkles during thermal annealing. GO nanosheets are bridged by PAA-derived carbon, enhancing the structural integrity at molecular level. These multiscale structural features facilitate rapid electron transport and efficient load transfer, conferring graphene aerogels with intriguing mechanical and electromagnetic interference (EMI) shielding properties. The emulsion-based graphene aerogel with an ultralow density of ≈3.0mg cm-3 integrates outstanding electrical conductivity, air-caliber thermal insulation, high EMI shielding effectiveness of 75.0dB, and 90% strain compressibility with superb fatigue resistance. Intriguingly, thanks to the gel-like rheological behavior of the emulsion, ultralight graphene scaffolds with programmable geometries are obtained by 3D printing. This work provides a general approach for the preparation of ultralight and superelastic graphene aerogels with excellent EMI shielding properties, showing broad application prospects in various fields.

Multi-scale microstructural construction in ultralight graphene aerogels enables super elasticity and unprecedented durability for impact protection materials

Ultralight graphene aerogels have gained extensive recognition in the impact protection field. However, attaining both elasticity and durability at low material density is challenging due to their intrinsic conflicts. Inspired by the mantis ootheca, we present a simultaneous improvement in the elasticity, durability, and density restrictions of ultralight graphene aerogels via constructing a multiscale honeycomb microstructure (MHM) within the graphene skeleton. This approach enables resulting graphene aerogel to achieve a strength per unit volume of 284.6 cm3 mg−1, the ability to recover its shape within 10 ms after an impact at 3.569 m/s, and maintain 97.2 % of its sample height after 20,000 cycles at 90 % strain. The operand analyses and calculation results reveal that the MHM structure facilitates this aerogel’s dual-stage stress transfer pathway. Initially, the macroscale honeycomb structure (millimeter-scale) of the graphene aerogels bear and transmit stress to the surrounding regions, followed by the microscale honeycomb structure (micron-scale) deformation to convert stress kinetic energy into elastic potential energy. This two-stage stress transition mechanism of the MHM structure can effectively mitigate excessive local stress and suppress strain localization, thus providing remarkable elasticity and durability. Ultimately, the obtained graphene aerogel demonstrates promising applications as a fall height detection device and impact protective material.

Superior broadband sound absorption in hierarchical ultralight graphene oxide aerogels achieved through emulsion freeze-casting

Ultra-lightweight aerogels have profound applications as advanced multi-functional sound-absorbing materials. At present, conventional aerogels are associated with pores with sizes too small for effective sound absorption in the audible range. In this work, we fabricated a hierarchically porous ultralight graphene oxide (GO) aerogel through a novel emulsion freeze-casting process of an air-in-water emulsion. Microstructural analysis of the aerogels reveals a hierarchical pore morphology consisting of highly inter-connected pores produced from the emulsion bubbles and the micro-pores produced by freeze-casting. Sound absorption measurements revealed that an aerogel with a surfactant-to-GO weight ratio of 1:1 displays an average absorption coefficient of up to 0.86 at a broadband frequency range between 250 Hz and 6300 Hz, a vast improvement by up to 58% as compared to conventional GO aerogels. Numerical microstructural models were developed to model the acoustic absorption phenomenon and understand the mechanisms behind enhanced sound absorption. These models identified the enhanced acoustic absorption as attributed to the increased air-wetting area as derived from the high reticulation rate in this hierarchical microstructure. Overall, we demonstrate the potential of leveraging the highly inter-dependent material-process-structure relationships of GO aerogel production to achieve hierarchical GO aerogels as advanced ultralight sound-absorbing materials.

Ultralight 3D Graphene Oxide Aerogel Decorated with Pd-Fe Nanoparticles for the Simultaneous Detection of Eight Biomolecules.

In this proof-of-concept study, an ultralight graphene oxide aerogel (GOx-Aero) decorated with bimetallic palladium-iron nanoparticles (Pd-Fe) was synthesized and immobilized on a glassy carbon electrode (GCE) for electrochemical sensor applications. The main objective of this work was to develop a sensitive electrochemical sensor capable of simultaneously detecting eight biomolecules, including ascorbic acid (AA), dopamine (DA), uric acid (UA), 8-hydroxyguanine (8HG), guanine (G), adenine (A), thymine (T), and cytosine (C). To the best of our knowledge, this is the first time that an electrochemical sensor has been able to detect eight biomolecules simultaneously. The bimetallic GOx aerogel significantly enhanced the performance of the sensor by increasing the electroactive area, conductivity, and anodic peak current response. The sensor demonstrated sharp, well-defined, and continuous oxidation peaks for all eight analytes of interest and wide linear ranges of 5.0-1750, 0.25-100.0, 0.5-500.0, 0.5-375.0, 0.5-500.0, 0.5-500.0, 5.0-1500.0, and 5.0-1500.0 μM for AA, DA, UA, 8HG, G, A, T, and C, respectively. The prepared sensor also exhibited excellent stability, reproducibility, and sensitivity with a very low limit of detection (LOD) of 553.7, 1.8, 69.6, 43.2, 42.9, 72.3, 57.2, and 318.4 nM for AA, DA, UA, 8HG, G, A, T, and C, respectively. The Pd-Fe-GOx-Aero-GCE was also tested in various real samples such as artificial saliva, artificial cerebrospinal fluid (CSF), salmon sperm DNA, and genomic DNA from calf thymus, where it demonstrated good recovery values. Additionally, the novel developed sensor was used to monitor the interaction between the anticancer drug, cisplatin, which has well-described binding affinity with the G and A bases in DNA. Overall, Pd-Fe-GOx-Aero-GCE displayed an extremely promising platform not only for the simultaneous detection of eight biomolecules in complex biological matrices but also for DNA-drug interaction studies toward the development of electrochemical high-throughput drug screening assays, which is of great importance in the field.

Ultralight, Compressive and Superhydrophobic Methyltriethoxysilane-Modified Graphene Aerogels for Recyclable and Selective Organic Pollutants Adsorption from Water

Ultralight, Compressive and Superhydrophobic Methyltriethoxysilane-Modified Graphene Aerogels for Recyclable and Selective Organic Pollutants Adsorption from Water

Ultralight graphene oxide/polyvinyl alcohol aerogel for broadband and tuneable acoustic properties

An ultralight graphene oxide (GO)/polyvinyl alcohol (PVA) aerogel (GPA) is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and sound transmission losses. The interaction between GO sheets and PVA molecules is exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffold. The aerogels possess an enhanced ability to dissipate sound energy, with an extremely low density of 2.10 kg m−3, one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimised the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times on acoustic properties and assessed the relationships between the acoustic and non-acoustic properties of the materials. Over the 400–2500 Hz range, the reported average sound absorption coefficients are as high as 0.79, while the average sound transmission losses can reach 15.8 dB. We envisage that our subwavelength thin and light aerogel-based materials will possess other functional properties such as fire resistance and EMI shielding, and will prove to be novel acoustic materials for advanced engineering applications.

Ultra-Light Graphene Tile-Based Phase-Change Material for Efficient Thermal and Solar Energy Harvest

A graphene tile based phase change material was reported to function as thermal storage material and light absorption material simultaneously, which achieved directly efficient solar-to-thermal con...

Solar activated crude oil cleanup using net-shape-formed ultralight graphene tiles

Accidental crude oil spills over a large water surface can wreck environmental and economic havoc. To mitigate such disasters, timely intervention to contain and recover oil before it spreads is critical. Standard lipophilic sorbents do not work because crude oil is too viscous to flow into them, especially in cold weather. This has led to the proposal of using graphene foam, also an excellent lipophilic sorbent, since it is a conductor and can be electrically heated, thus rendering the crude fluid enough to absorb. Yet wiring, powering and electrically heating any mass over a large area in high seas is clearly a challenge. Here we present a solution using a solar-activated graphene tile: within seconds upon exposure to daylight, it heats up and absorbs, eventually filling crude oil into 74 % of its own volume. It may be further coated by a lipophilic oil-permeating thermal insulation to become a light-absorbing, heat-retaining and oil-absorbing black hole. Capable of withstanding high heat up to 600 °C, tiles can be rejuvenated by ridding themselves of adsorbed oil in self-combustion, allowing even a small supply of tiles to last and contain oil spill for some time. The reusable tile is made by pyrolyzing a poly(vinylidene chloride) foam of an identical size and shape, obtaining a density of 16 kg m−3 and a strength of 11.7 kPa. Upon emergency, tiles initially installed as ultralight load-supporting constructs on oil-production platforms and crude-transport vessels become immediately available for repeated oil absorbing at 41 times their own weight. Therefore, they can provide the crucial first-response kit for mitigating oil-spill disasters.

Twist-spinning assembly of robust ultralight graphene fibers with hierarchical structure and multi-functions

Graphene fibers attract tremendous interest due to their huge potentials in energy devices, pressure sensors, and electro-heaters. However, there still remain some challenges to prepare robust ultralight graphene fibers by a dry spinning strategy due to the low aspect ratio, poor entanglements and high surface tension of graphene sheets. Here, we present a facile and green dry twist-spinning assembly strategy to prepare ultralight graphene fibers with hierarchical structure. Because of hierarchical assembly, stronger entanglements of graphene nanoscrolls endow ultralight graphene fibers high mechanical strength of ∼3.9 ± 0.5 MPa. Such light graphene fibers show high specific electrical conductivity of 0.95–1.67 S m2 g−1 and specific thermal conductivity of 42.3–100 W cm2 K−1 g−1, which are comparative to that of copper and silver. Therefore, they exhibit ultrafast electro-thermal response (5943 K s−1), which exceeds the record value of carbon nanotube (CNT) film ever reported (3500 K s−1). Such facile and green dry spinning strategy offers new opportunity to prepare and apply the ultralight graphene fibers.

Self-Healing Graphene-Reinforced Composite for Highly Efficient Oil/Water Separation.

One of the most pervasive environmental problems is oily sewage; emerging materials are needed that could effectively solve this global challenge. Special wetting materials typically combine micro/nanoscale hierarchical structures with a low surface energy, which could produce superhydrophobic performance and these superhydrophobic materials are very important for a wide variety of applications, including self-cleaning and antiadhesives. However, the majority of these manmade materials still suffer from poor durability, which seriously hinders their practical applications. A better choice is that use of supramolecular materials with self-healing ability, which could provide an efficient method to solve materials poor durability problem. However, lightweight materials with special wettbility and self-healing still remain a challenge. In this work, we confine polyborosiloxane (PBS) in an ultralight graphene network to form a robust, special function graphene foam that has the ability to self-repair. Hydroxyl terminated poly(dimethylsiloxane) and boric acid as the as raw material were used to synthesis PBS at room temperature. The as-prepared composite network could be compressed and their properties fully restored without an external stimulus after being subjected to repeated damage. In addition, the prepared composite foam retains the porosity of the original graphene foam. The present work suggests encouraging applications of the self-healing graphene/PBS foam in water/organic solvent separations.

Rational Design of Layered SnS2 on Ultralight Graphene Fiber Fabrics as Binder-Free Anodes for Enhanced Practical Capacity of Sodium-Ion Batteries

HighlightsLayered SnS2 nanosheets/reduced graphene fiber (SnS2@rGF) hybrid fabrics were fabricated as binder-free electrodes.Ultralight rGF fabrics could increase the active materials loading to a high level of 67.2 wt% in the whole electrode, which is much higher than that of traditional slurry coating electrodes by using Cu or Al foil as current collectors.The practical capacity based on the weight of electrode could increase to as high as ~ 538 mAh g−1 exceeding to the slurry coating electrodes.

A simple method for preparing ultra-light graphene aerogel for rapid removal of U(VI) from aqueous solution

In this study, graphene aerogel (GA) was successfully prepared through a simple hydrothermal method. The resulting GA exhibited a porous network structure with a large specific surface area (350.8 m2/g), ultra-light mass and easy separation from water. The pHIEP value of the GA was estimated to be 3.5. The adsorption process and the factors that affect adsorption capacity were studied. The adsorption could be conducted in a wide pH range from 2.0 to 7.0. The maximum adsorption capacity of GA towards U(VI) at pH 4.0 and T = 298 K was 238.67 mg/g calculated from the Langmuir model. The GA had greatly rapid adsorption property for the removal of U(VI) at pH 4.0. Kinetic data showed good correlation with pseudo-second-order equation. Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry characterizations showed that GA adsorbed U(VI) through chemical interaction by oxygen-containing and nitrogen-containing groups functional groups. The results show that GA has excellent application potential as an adsorbent material for removing U(VI) from aqueous solution.

Fabrication of 3D ultra-light graphene aerogel/Bi2WO6 composite with excellent photocatalytic performance: A promising photocatalysts for water purification

Abstract Herein, we fabricated an ultra-light graphene aerogel/Bi2WO6 (GA/BW) photocatalyst with macroscopic 3D architecture via in-situ synthesis, which had preferable activity for organic wastewater purification. We carefully characterized the physical and chemical properties of this macroscopic 3D architecture, finding that the flower-like Bi2WO6 (BW) uniformly loaded on the surface of GA, improving the visible light absorption performance, photon-generated carrier separation efficiency and organic contaminants adsorption ability, as well as photocatalytic ability compared with that of pure BW powders. When the mass ratio of GA and BW is 6:8, the degradation efficiency of rhodamine B (RhB) and sulfanilamide (SN) can reach 97.49% and 55.81% in 120 min, respectively. The as-prepared GA/BW composite is ultra-light and suitable for practical wastewater purification due to its flexibility and recyclability. The trapping experiments involved the main active species in the photocatalytic process were carried out and the results indicated that the h+ is the dominant oxidative species for the degradation of RhB.

Graphene‐Based Composites Combining Both Excellent Terahertz Shielding and Stealth Performance

AbstractStrong terahertz‐response material which exhibits both excellent terahertz shielding and stealth performance is promising in practical applications of terahertz technology. Here, ultralight graphene foam (GF) and multiwalled carbon nanotubes/multiwalled graphene foam (MGF) have been first demonstrated to achieve both superior terahertz shielding and stealth performance due to the dominant absorption loss with negligible reflection. The terahertz shielding effectiveness values of GF and MGF, both 3 mm thick, reach up to 74 and 61 dB. Meanwhile, their average terahertz reflection loss values are achieved up to 23 and 30 dB, respectively, which are the best results in existing broadband terahertz shielding/stealth materials. Importantly, their qualified absorption bandwidths (reflection loss value larger than 10 dB) cover the entire measured frequency band of 0.1–1.6 THz. Furthermore, the quantitative relationships between the terahertz shielding effectiveness, reflection loss, and material parameters are accurately established, which should facilitate the material design for terahertz shielding and stealth. Comprehensively considering the important indicators of density, bandwidth, and intensity, the specific average terahertz shielding coefficient and the specific average terahertz absorption performance are achieved up to 1.1 × 105 and 3.6 × 104 dB cm3 g−1, respectively, which is over thousands of times larger than other kinds of materials reported previously.

Ultralight graphene micro-popcorns for multifunctional composite applications

Graphene has been widely applied in polymer nanocomposites due to its charming physical and chemical properties. However, the performance of graphene/polymer composite is hampered by the strong stacking tendency of graphene sheets. Here we introduce graphene micropopcorns (GMPs) with a hollow structure and a low stacking degree as an efficient additive for multifunctional composites. GMPs are massively fabricated via a facile thermal treatment of spray-dried graphene oxide (GO) powder. GMPs feature a low tap density (6–8 mg cm−3), a high specific surface area (947 m2 g−1) and a good solvent absorption capability (62 g g−1). This micro form of graphene can act as electrical conductive fillers with a low percolation threshold of 0.18 vol% and microcapsules of phase change materials with a 358% enhancement in thermal conductivity. Besides, the microwave absorption (MA) performance of GMPs/paraffin composites outperforms most graphene-based materials ever reported but with a record-low filler content (2.5 wt%). The large-scale producible GMPs enable an efficient method to utilize graphene to grant conventional materials with better performances and new functions.

Direct 3D Printing of Ultralight Graphene Oxide Aerogel Microlattices

AbstractGraphene aerogel microlattices (GAMs) hold great prospects for many multifunctional applications due to their low density, high porosity, designed lattice structures, good elasticity, and tunable electrical conductivity. Previous 3D printing approaches to fabricate GAMs require either high content of additives or complex processes, limiting their wide applications. Here, a facile ion‐induced gelation method is demonstrated to directly print GAMs from graphene oxide (GO) based ink. With trace addition of Ca2+ ions as gelators, aqueous GO sol converts to printable gel ink. Self‐standing 3D structures with programmable microlattices are directly printed just in air at room temperature. The rich hierarchical pores and high electrical conductivity of GAMs bring admirable capacitive performance for supercapacitors. The gravimetric capacitance (Cs) of GAMs is 213 F g−1 at 0.5 A g−1 and 183 F g−1 at 100 A g−1, and retains over 90% after 50 000 cycles. The facile, direct 3D printing of neat graphene oxide can promote wide applications of GAMs from energy storage to tissue engineering scaffolds.

Vapor–Liquid Deposition Strategy To Prepare Superhydrophobic and Superoleophilic Graphene Aerogel for Oil–Water Separation

The problems of high temperature and volume shrinkage are frequently encountered in the process of fabricating superhydrophobic graphene aerogels. We present ultralight graphene aerogels with superhydrophobicity and superoleophilicity by a vapor–liquid deposition process. The graphene aerogels are prepared by graphene oxide assembled into monolithic graphene hydrogel in dopamine-mediated aqueous solution at mild temperature and a sealed reaction, then by directional freezing and freeze-drying. Subsequent fluorinated alkyl silane is introduced to produce ultralight graphene aerogel by vapor–liquid deposition treatments; the surface of the aerogel has outstanding superhydrophobicity and superoleophilicity with water and oil contact angles of 160.2° and 0°, respectively. In addition, the resulting graphene aerogels showed super low density, large specific surface area, excellent adsorption capacities, and superior adsorption recyclability. Its adsorption capacity was higher than 109 g/g for the used common o...

Facile one-pot preparation of nitrogen-doped ultra-light graphene oxide aerogel and its prominent adsorption performance of Cr(VI)

A novel nitrogen-doped ultra-light graphene oxide (GO) aerogel with three-dimensional (3D) network structure is used for removing of Cr(VI) from aqueous solution, which is fabricated by a facile one step hydrothermal self-assembly process and an environmentally friendly freeze-drying technique. GO and organic amine are used as the precursors to synthesize the aerogels, in which pyrrole and Tetraethylenetetramine (TEPA) are introduced as nitrogen sources to obtain the amino functional groups, meanwhile, they also play the roles as cross-linking agents to control the assembly of GO sheets in the 3D structure. The obtained TEPA/polypyrrole/GO aerogel (TPGA) has a high adsorption capacity for Cr(VI) anions (up to 408.48 mg/g) at an optimal pH of 2.0. The kinetics process of Cr(VI) adsorption on TPGA can be fitted well with the pseudo-second-order kinetic model. The mechanism of adsorption is analyzed by intraparticle diffusion and external film diffusion models, which indicates that the overall rate of Cr(VI) adsorption process is influenced by multi-steps. The isotherm and thermodynamic studies confirms that adsorption of Cr(VI) on TPGA is a spontaneous and endothermic process in the monolayer adsorption pattern. Furthermore, the prepared TPGA exhibits a good regeneration ability and satisfactory recovery for Cr(VI) anions in practical water samples. This work provides a simple and environmentally friendly method to synthesize the nitrogen-doped GO aerogel, which show a great potential and promise for practical application in the field of waste water treatment.

Ultrasensitive Pressure Sensor Based on an Ultralight Sparkling Graphene Block.

Herein, we develop a supersensitive pressure sensor based on a fully air-bubbled ultralight graphene block through a simple sparkling strategy. The obtained sparkling graphene block (SGB) exhibits excellent elasticity even at 95% compressive strain and rebounds a steel ball with an ultrafast recovery speed (∼1085 mm s-1). Particularly, the SGB-based sensor reveals a record pressure sensitivity of 229.8 kPa-1, much higher than other graphene materials, because of the highly cavity-branched internal structure. Impressively, the pressure sensor can detect the extremely gentle pressures even beyond the real human skin and hence are promising for ultrasensitive sensing applications.

Prominent adsorption performance of amino-functionalized ultra-light graphene aerogel for methyl orange and amaranth

Amino-functionalization is an effective and facile way to modify the surface of adsorbent. A facile strategy to fabricate polyethyleneimine-functionalized graphene aerogel (PFGA) integrating superhigh adsorption ability, selectivity, pH-sensitivity and reusability was developed. The maximum adsorption capacities of the PFGA for methyl orange and amaranth were as high as 3059.2mgg−1 and 2043.7mgg−1, respectively, the highest capabilities among the reported adsorbents for both dyes. The microcosmic interaction models of the two dyes and PFGA were outlined to describe the relationships between dye structures and adsorption behaviors. Owing to the different affinities of PFGA for anionic and cationic dye, anionic dye methyl orange was able to be selectively separated from the dye mixture. In the experiment of competitive adsorption of acid dyes with different structures, amaranth with more sulphonate groups was preferentially adsorbed. In addition, PFGA showed meaningful pH-sensitive adsorption ability, enabling dye-adsorbed PFGAto be fully regenerated as soon as it was exposed to the solution of pH 11. The study on polyethyleneimine-functionalization is meaningful for the development of high adsorption capacity adsorbents and amino-functionalization or other functionalized materials.