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Graphene oxide (GO) has been widely considered for electrochemical energy storage applications due to its improved physical, chemical, and electronic properties over pure graphene. The oxygenated groups adsorbed on the surface of the GO lead to greater ionic mobility, and greater density of states while maintaining the same specific area of pure graphene. In parallel, the morphology of the electrode, structured in the form of pores, has a huge impact on the device's properties by favoring electrode–electrolyte interactions, expanding the contact area between the two. Although there is already a considerable volume of computational work on the performance of graphene oxide electrodes as well as on porous carbon electrodes, the combined analysis of both effects (the chemical functionalization and the porous morphology) in a single device to mimic a supercapacitor has not yet been presented. In this work, atomistic molecular dynamics simulations were performed to study the structural aspects of porous graphene oxide electrodes in three different ionic liquids held under constant potential. In addition, a detailed description of the electrode charging mechanisms in the presence of each of the electrolytes is presented. [Display omitted] [ABSTRACT FROM AUTHOR]

Disordered wrinkles inevitably appear in the fluid assembly process of graphene and heavily depress performances of assembled graphene papers. Achieving high plasticity enables the post modulation to rearrange wrinkles by stretching. Here, we obtain an over 100% improved plasticity by intercalating oligomer into graphene oxide (GO) laminates and fabricate strong, stiff and conductive graphene papers (GPs) via post stretching. The intercalated oligomer activates the mobilization of GO sheets and achieves high plasticity of solid GO papers. The improved plasticity allows high stretching ratio and the post-stretched GP features regular orientation (0.95) of graphene sheets and aligned fine wrinkles. The crystalline GPs have a high tensile strength up to 1.3 GPa, Young's modulus of 92.9 GPa and highly electrical conductivity (1.05 × 105 S m−1). The greatly improved plasticity by oligomer extends the processing capability of graphene materials and the strong and conductive GP can be assembled in high performance nanocomposites with excellent electromagnetic interference shielding effectiveness (EMI SE). [Display omitted] • Intercalating oligomer greatly enhances plasticity of graphene oxide laminates for the improved interlayer friction. • The greatly enhanced plasticity enables to efficiently eliminate disordered wrinkles of assembled graphene sheets. • The crystalline graphene paper (GP) exhibits superior mechanical and electrical properties. • The (GP-based) laminated composite shows high tensile strength and electromagnetic interference shielding effectiveness. [ABSTRACT FROM AUTHOR]

As electromagnetic pollution becomes more and more serious nowadays, efficient electromagnetic interference (EMI) shielding materials with lightweight, elegant mechanical behavior, and designable structure become desperately needed. Multiple reflections in materials can improve the EMI shielding efficiency effectively, which is a priority when designing EMI shielding materials. Inspired by the fabrication of toasts, the dough can be stretched into extremely thin sheets, and the large-scale deformation makes the micro components in-plane arranged in the porous carbon. The obtained porous carbon exhibits an anisotropic EMI shielding performance with a ratio of 1.45:1 (vertical to the sheets: parallel to the sheets) due to the multiple reflections between the oriented layers. Furthermore, water for kneading is replaced with graphene oxide (GO) solution, and the GO@dough is stretched into thin sheets with GO nanosheets in-plane oriented. The obtained porous carbon exhibits the highest SET value of 33.95 dB in X band (vertical to the sheets). Additionally, by arranging the sheets with a gradient concentration of reduced GO, surface impedance matching is improved with an increased value of SEA, and the gradient porous carbon exhibits elegant EMI shielding performance over 54 dB and average absolute shielding effectiveness reaching 530 dB cm2/g throughout the X band. Inspired by the fabrication of toasts, a simple but effective preparation of in-plane-oriented porous carbon is achieved. The macro-scale deformation can make the micro components (micron pores, nanosheets like rGO, etc.) in flexible materials present in-plane oriented distribution. After mixing of reduced graphene oxide, the electromagnetic properties of the dough sheets can be regulated artificially. By arranging the dough sheets with an increasing concentration gradient of rGO, the EMI shielding performance of the top-incident electromagnetic waves is dramatically improved. The obtained porous carbons are lightweight with elegant anisotropic mechanical and EMI shielding performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanoporous graphene is promising for the fabrication of high-performance organic solvent nanofiltration (OSN) membranes owing to the excellent chemical resistance of graphene in organic solvents. Moreover, the nanopores increase solvent permeance by providing diffusion channels. However, conventional chemical and physical etching methods are generally applicable on a laboratory-scale, and the large-scale fabrication of these structures is challenging. Herein, a large-area nanoporous multilayer graphene oxide (NMG) membrane was prepared using a combination of slot-die coating and confined thermal treatment. Graphene oxide (GO) was coated on polymeric supports using a slot-die coater, which is generally used for continuous coating in industry. Afterward, the GO membrane was treated using a hot-pressing method to activate the nanopores on the graphene surface and weld the polymeric support with the graphene layer. The interlayer and pore structure of GO were tuned by modulating the hot-pressing time, and its influence on OSN performance was systemically investigated. The optimized NMG membrane exhibited a high ethanol permeance of 300 Lm−2h−1bar−1 and a sharp molecular weight cut-off of 500 g/mol. Furthermore , the enhanced adhesion between graphene and the polymeric support enables mechanically stable membrane operation under cross-flow conditions for 30 days, which is the longest test time reported for two-dimensional material-based OSN membranes thus far. [Display omitted] [ABSTRACT FROM AUTHOR]

The rise of reverse osmosis membranes (RO) has attracted significant attention, which is pivotal to addressing the water shortage. Superior permeability and high selectivity are extremely critical criteria for RO membranes. Therefore, in this study, we reported a novel strategy: pressure spray interface polymerization (PSIP) to prepare ultrathin RO composite membranes. In the approach, besides the developed novel technique, highly permeable holey graphene oxide (HGO) containing nanopores was also used to refine the size of the transport nanochannels during the reaction of m-phenylenediamine (MPD) and the trimethyl chloride (TMC). Meanwhile, the electrostatic interaction between the HGO and MPD provided a solid guarantee for good dispersion in the composite membrane. The resultant pressure spray interface polymerization-highly permeable holey graphene oxide (PSIP-HGO) composite membrane displayed high salt rejection and water permeance, which showed high water permeance of 4.0 Lm−2h−1bar−1 and Na 2 SO 4 rejection of 95% in a concentration of 2000 ppm under 5 bar. Moreover, the PSIP-HGO membrane showed outstanding long-term stability and high chemical stability. Therefore, our work may provide a feasible pathway for designing advanced RO membranes for water desalination. [Display omitted] [ABSTRACT FROM AUTHOR]

As a promising lubricate additive, the excellent lubrication performance of graphene oxide (GO) is attributed to the formation of GO tribofilm. However, the poor adsorption of GO on engineering materials surfaces limits the formation of tribofilm, resulting in losing the expected lubricating performance as a lubricant additive. In this study, to improve the adsorption of GO on bearing steel, the boronized functionalization layer was prepared on a bearing steel surface by an electrochemical boronizing process. Our experiment results indicate that an ultralow friction state with a friction coefficient (COF) of 0.03 was achieved on the boronized surface lubricated with 1 wt% GO nanosheets as water-based additives. Together with TEM, EDS and Raman analysis, we confirmed the formation of GO tribofilm with a thickness of 280 nm on the sliding surface due to the synergistic effect of the boronized surface and GO. Molecular dynamics (MD) simulation revealed that the high adhesion energy between the boronized surface and GO endows the preferential adsorption of GO on the sliding surface to form the tribofilm. The ultralow interlayer shear strength of GO tribofilm further contributed to the impressive synergistic lubrication performance. Our study expands the application scope of the ultralow friction behavior of GO by enhancing its adhesion energy on the engineering alloy surface. [Display omitted] • Synergistic lubrication effect of GO nanosheets and boronizing surface was proved. • The adhesion energy of GO on steel surface was enhanced by boronizing treatment. • The preferential adsorption of GO on the substrate was ensured during sliding. • A GO tribofilm with a thickness of 280 nm was formed on the sliding surface. • An ultralow friction state was achieved on the steel lubricated by GO solution. [ABSTRACT FROM AUTHOR]

Dynamic nuclear polarizing (DNP) technique in nuclear magnetic resonance (NMR) is a powerful tool for a microanalysis. Nevertheless, it has not been applied to analyses of carbon materials such as graphene oxide (GO) and amorphous carbon effectively because of the electroconductivity and microwave absorption of the carbon, which attenuate the enhancement effect of DNP. For this study, we applied DNP-NMR to analyses of surface functional groups on GO and sucrose-derived carbon to evaluate the method. The 1H–13C cross-polarization magic-angle spinning (CP/MAS) DNP-NMR of a GO sample with AMUPol (polarizing agent) showed 2.2-times-enhanced peaks of 13C in epoxide, bonding to hydroxyl group, and in the graphene plane. Signal enhancement was raised by AMUPol radicals neighboring the surface functional groups and the graphene planes on GO particles, although attenuation by temperature rise must be considered. Furthermore, additional new peaks assigned to CH 3 group on the GO particle surface were highly enhanced and were observed clearly only by the accumulations of 64 scans. For sucrose-derived carbon, DNP-NMR clearly revealed the –OH group on the carbon surface or carbon edge by heat treatment, which was not possible using conventional CP/MAS experiments. Cross Effect was found to be dominant in signal enhancements of the functional groups on GO and sucrose-derived carbon samples, except for the CH 3 groups on GO. The CH 3 enhancement is ascribed mainly to the Overhauser effect or solid effect. [Display omitted] • Dynamic nuclear polarizing was used for NMR measurement of carbon materials. • Surface functional groups on GO and sucrose-derived carbon were analyzed. • 1H–13C CP/MAS DNP-NMR of GO with polarizing agent showed enhanced peaks. • Methyl group signals on GO particle surfaces were highly enhanced. • DNP with appropriate radical sources can contribute to the surface analysis of carbon. [ABSTRACT FROM AUTHOR]

This article discusses the morphology and thermomechanical properties of graphene oxide (GO) paper sheets and GO paper composites reinforced with carbon fibers. GO paper was fabricated using GO paste obtained by the condensation of GO aqueous solution synthesized using the Hummers' method. Carbon fibers were implemented to improve the mechanical properties of the pristine GO paper. All the investigated papers were subjected to thermal treatment to check thermo-related morphological and mechanical properties. The results presented in this study allowed for the deeper insight into morphological, structural, and mechanical volume and surface-related properties of pristine GO and GO-based composite materials reinforced with carbon fibers. We showed that there are two important factors that should be taken into consideration for the design and fabrication of GO-based papers. These factors were the concentration of the reinforcing agent and the thermal reduction of the papers. Both factors have influenced the final properties of the resulting GO-based papers. For the first time, it was revealed how the addition of the reinforcing material affects the GO paper thermal expansion coefficient. [Display omitted] [ABSTRACT FROM AUTHOR]

Functionalization of graphene's two-dimensional sheets can be used to modify the physical properties of graphene, such as changing its conductivity or inducing ferromagnetism, which is of broad interest for a myriad of applications. However, functionalized graphene can possess significant structural disorder that is often overlooked and is difficult to characterize quantitatively. Here we investigate hydrogenated graphene nanopowder (H-Gr) produced by Birch reduction of graphene oxide. By combining complementary x-ray and neutron diffraction, we show how to quantitatively characterize the H-Gr nanostructure, including the hydrogen content. We show that the majority of the H-Gr consists of highly disordered molecular-scale carbon while a small portion of the sample contains few-layered graphene having an expanded interlayer spacing. Modeling the coherent diffuse scattering for both x-ray and neutron diffraction, and comparing it with the incoherent neutron scattering, the hydrogen to carbon ratio was measured and it was determined that most of the hydrogen resides within the disordered carbon rather than in the graphene. Evidence is presented for hydrogen clustering as well as for hydrogen bonded perpendicular to the plane of molecular-carbon bonds. Our quantitative approach to characterizing carbon nanopowders has broad relevance to understanding disorder and bonding of hydrogen in graphitic carbons and other nanomaterials. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene as a sensory platform with luminescent tags faces agglomeration and fluorescence quenching challenges. Therefore, composite materials derived from graphene and mesoporous silica are studied to address the issues with their cooperative actions. However, such materials are rare and are never explored for simultaneous sensing and adsorption studies. Therefore, in this work, a modified approach was made to produce better quality graphene oxide, which was subsequently used for preparing reduced graphene oxide/silica composite (rGOmSiO 2) and further functionalized with quinoline-based ligand to create a functional composite (rGOmSiO 2 @BIQINOL) for specificity. This material shows very selective TURN-ON fluorescence sensing of zinc-ion among various cations and anions through a coordination-driven excimer formation (rGOmSiO 2 @BIQINOL@Zn). Subsequently, the above Zn-adduct shows a TURN-OFF fluorescence emission with ATP (adenosine triphosphate) via coordination-driven excimer breakdown (rGOmSiO 2 @BIQINOL@Zn@ATP). A sequential probing of Zn2+ and ATP with a very sensitive limit of detection (27 nM & 157 nM, respectively) was demonstrated. The adsorption studies show high adsorption capacities for Zn (595 mg g−1) and ATP (445 mg g−1) with the material's recyclability. Also, the materials were used precisely for real sample quantification of Zinc & ATP. The simultaneous detection and adsorption of Zn and ATP with material recyclability is advantageous compared to literature reports. [Display omitted] • A modified method was adopted to synthesize better-quality graphene oxide. • A Functional composite of graphene/silica was used to demonstrate dual functions of sensing and adsorption. • The functional composite was used for bimodal sequential probing of zinc and ATP with a nanomolar level of sensitivity. • The quantification of zinc and ATP in real samples were achieved using the functional composite. [ABSTRACT FROM AUTHOR]

The metal-organic frameworks-derived carbon-based electromagnetic wave (EMW) absorbing (EMWA) materials have attracted extensive attention. However, it still maintains a challenge to design the kind of materials with wide effective absorption bandwidth (EAB). Herein, a series of reduced graphene oxide (RGO) supported symmetrical lotus-like cobalt/manganese oxide/porous carbon (Co/MnO/PC/RGO) composites were synthesized by hydrothermal method and subsequent carbonization process. Impressively, the symmetrical porous structure and the special component could synergistically improve EMWA capacity. On the one hand, the symmetrical porous structure and magnetic component could optimize impedance matching, which were conducive to more EMW entering into the sample. On the other hand, the abundant heterointerfaces enhanced the interface polarization and the EMWA performance of the sample could be also regulated by the change of GO content in the mixture. When the GO content was 9 wt%, a minimum reflection loss value of −50.1 dB and the corresponding EAB value of 5.1 GHz (11.9–17.0 GHz) was achieved at a thickness of 2.0 mm. The excellent EMW performance of the sample stemmed from the increased dielectric loss and magnetic loss as well as improved impedance matching. As a consequence, this work authenticated a novel pathway to construct the carbon-based EMW absorbers with broad EAB. [Display omitted] [ABSTRACT FROM AUTHOR]

Renewable and low-cost biochar's intrinsic porous structure limitations make its porous structure mediation highly significant for performance enhancement. We employ graphene oxide (GO) as an additive at a low dosage for the deed-leaf-derived biochar's microporous structure mediation to promote the wastewater treatment ability toward a typical antibiotic pollutant - tetracycline hydrochloride (TCH). While KOH-based activation enables biochars with a microporous structure and improved graphitization, GO transforms part of micropores of such activated biochar into mesopores (i.e. forming hierarchical porosity), driven by the thermal pyrolysis of oxygen groups enriched on GO. The GO additive-induced process overcomes the loss of surface resulted from conventional pore widening, promoting mass transport as well as improving the accessibility to pore interiors and compatibility for large-size contaminant molecules. The increase of the sp2-to-sp3 carbon ratio from 0.59 to 0.79 with GO incorporation facilitates π-π stacking interactions with aromatic pollutants (including TCH and organic dyes), which are more critical than the electrostatic attraction and hydrogen bonding interactions. Apart from superior adsorption capacities of 193.43 and 336.70 mg/g obtained at 303 and 313 K, respectively, the graphene-modified hierarchically porous biochar is recyclable, reusable, resistant to interfering metal cations, and universal for binding a range of organic pollutants bearing different charge states, demonstrating equilibrium adsorption capacities of 186.58, 190.38, 268.43, and 254.88 mg/g for TCH, methylene blue, Rhodamine B, and methyl orange, raised by 26.8%, 41.6%, 32.1%, and 105.3%, respectively, compared to the counterpart without GO-enabled micropore widening. The greater adaptability to different-size pollutants presents higher practical application viability. [Display omitted] • GO additive empowered the widening of microporous biochar from 3.0 to 3.3 nm. • GO additive modification improved the sp2-to-sp3 carbon ratio from 0.59 to 0.79. • GO additive incorporation promoted tetracycline capturing capacity to 336.70 mg/g. • The biochar-based adsorbent modified with GO was reusable, tolerant and universal. • π-π stacking interactions drove the efficient adsorption of pollutants. [ABSTRACT FROM AUTHOR]

Confining active nanoparticles in hierarchically porous carbon to construct intercalation and conversion coupling mechanisms is one promising way to achieve high-performance energy storage electrodes. However, this carbon with fragile mesoporous walls always suffer from fragmentation during the ion intercalation/deintercalation process, which would lead to the blocking of the whole electron transport network and the detachment of active particles, resulting in the capacity attenuation. Herein, reduced graphene oxide (rGO) bubbles are successfully introduced into N-doped hierarchically porous carbon (rGO-NPC) confined conversion-type nanoparticles to enhance their electrochemical performance. The rGO bubbles not only can afford an uninterrupted electron transport network, accelerating the reaction kinetics of active nanoparticles, and thus improving the capacity, but also can buffer the volume change of porous carbon, maintaining the integrity of electrode materials, and thereby, enhancing the cycling performance. With FeS 2 as an example, when employed in Na/K-ion capacitors (SICs/KICs), the FeS 2 @rGO-NPC electrode can reach a high maximum energy/power density (110 Wh kg−1/20935 W kg−1 for SICs and 134 Wh kg−1/17973 W kg−1 for KICs) with a great cycling performance (82%/91% of capacitance retentions at 2 A g−1 after 10000/15000 cycles for SICs/KICs). This work indicates a promising way for designing porous carbon-based anodes with high-performance for alkali metal ions storage. [Display omitted] [ABSTRACT FROM AUTHOR]

The ultra-loose and lightweight reduced graphene oxide/cellulose nanocrystal (rGO/CNC) hybrid aerogel was developed by hydrothermal method. Owing to the dispersibility and plentiful chemical groups of CNC, a variety of rGO/CNC hybrid aerogels with tunable dimensions were formed, thereby overcoming the limitation of size control of rGO aerogels by hydrothermal treatment. Moreover, rGO/CNC hybrid aerogel was endowed with ample functional groups, ultra-loose structure, and abundant micro/meso-pores, which allowed the composite exhibit excellent performance for capturing organic pollutants. With the use as solid-phase microextraction (SPME) coating to extract and determine polycyclic aromatic hydrocarbons (PAHs), the rGO/CNC composites presented superior extraction capacities for PAHs than pristine rGO and commercial SPME coatings due to the synergistic effects of π-π stacking, chemical groups bonding, and fast internal transfer in thick rGO/CNC layers. The proposed analytical method presented good linearity (R2 ≤ 0.9988) in concentration of 0.1–2000 ng L−1, low limits of detections (0.012–0.076 ng L−1), and excellent reproducibility. Finally, the proposed method was applied to determine PAHs from real water, and obtained satisfactory recoveries. This study proposed a novel method for regulating rGO aerogel structures, and confirmed its effectiveness for efficiently capturing organic pollutants from water. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates a novel approach of improving the mechanical performance of scarf-repaired carbon fiber reinforced composites by integrating nanomaterials in the patch constituents. Two distinct types of carbon-based nanomaterials, thermally exfoliated graphene oxide grade-2 (TEGO) and Epocyl™ 128–06 (MWCNT) are integrated into the patch resin matrix and fiber/matrix interface in an upscaled manner. Another group of composites are repaired with pristine patches in accordance with the existing and prevalent composite repair method. Compared to the reference panel, 109.9%, 99.7% and 99.3% stiffness recoveries are achieved for the patches with CNT and TEGO-incorporated resin matrices and TEGO-electrosprayed fibers, respectively. Location-wise analyses of the test data show that the stiffness, strength, Poisson's ratio, and strain values depend on the number of patch plies in each specimen. Fractographic inspections show that the failure sites shift towards the outer areas of the scarf region demonstrating an enhanced stress redistribution due to the nanomaterials. SEM observations show that nanoparticles affect toughening mechanisms based on the type, location, and alignment of the nano-reinforcement, which in turn limits the shear-dominated failures (SDF) in the baseline and pristine patch repair system. In CNT- and TEGO-reinforced resin patches, efficient crack bridging and fracture plane tilting/twisting or crack bifurcations are observed whereas the electrosprayed TEGO particles positioned at the perimeter of fibers operate as a shield for the fibers to prevent SDFs. These findings demonstrate that failure behavior of repair systems and therefore their mechanical performance are governed by the type of nano-reinforcement and its integration process. [Display omitted] • Nano-integrated patches restore stiffness and strength, and prevent patch loss. • Carbon nanotubes dispersed in the patch matrix enhance the interfacial adhesion. • Randomly oriented graphene oxide flakes in the matrix hinder shear dominated failure. • Electrosprayed graphene oxide shields the tows, protecting them from transverse cracks. [ABSTRACT FROM AUTHOR]

In biological fluids, the concentration of dopamine (DA) provides an important information about neurodegenerative disorders such as Parkinson's disease, schizophrenia and other DA-related ailments like hyperprolactinemia. Therefore, its accurate determination is crucial for the early diagnosis and monitoring of these syndromes. Herein we report a new approach that enables highly sensitive and free-interference of DA electroanalysis. The electrocatalytic properties of silver nanoparticles (AgNPs) towards DA and their ability to limit, in-situ, the uric acid (UA) oxidation were successfully combined with the electron transfer properties of pristine MWCNTs in a nanocomposite (AgNPs@MWCNTs). This nanomaterial showed complete elimination of UA interference and enhanced electron transfer kinetics. Subsequently, AgNPs@MWCNTs properties were successfully synergized with the great ability of graphene oxide (GO) to attract DA while repelling ascorbic acid (AA) and UA via electrostatic interactions, to carry out an electrode material (GO-AgNPs@MWCNTs). AgNPs@MWCNTs were characterized by XRD, Raman spectroscopy, HR-TEM and EDX. The successful GO synthesis was confirmed by XRD, Raman spectroscopy and XPS while its exfoliation and uniform distribution of AgNPs@MWCNTs on its layer surfaces were evidenced by FE-SEM and HR-TEM. The resulting DA sensor showed high sensitivity and complete suppression of UA and AA interferences. Calibration in the concentration range of 0.5–6.5 μM in the presence of 300 μM of AA and 500 μM of UA showed a linear response (R2 = 0.99944) with a detection limit of 2.58 nM (S/N = 3). Moreover, the prepared sensor showed good repeatability, reproducibility, long-term stability and satisfactory recoveries in human serum samples. [Display omitted] • A new approach for highly sensitive and free-interference DA sensing was developed. • The role of each material used to fabricate the associated sensor was summarized. • Fabricated sensor suppressed AA and UA interferences and showed a nanomolar LOD. • Prepared sensor showed good repeatability, reproducibility and long-term stability. • Developed sensor showed satisfactory recoveries in human serum samples. [ABSTRACT FROM AUTHOR]

Due to its woven structure, rich inner voids and high electrical conductivity, carbon fiber cloth (CFC) is considered as a promising three-dimensional (3D) current collector for lithium metal anode. However, it is usually inevitable that metallic Li plates on top of CFC as Li ions are instantaneously reduced when they reach the upper surface of CFC, which impedes the utilization of the inner space of CFC for accommodating Li deposition and causes poor cyclic stability of Li anode. In this study, by decorating a thin layer of graphene oxide (GO) on the surface of CFC using an electrophoresis method, an all-carbon 3D current collector with electrical conductivity differences in the vertical direction is fabricated. The graphene oxide layer with poor electrical conductivity induces downward electroplating of metallic Li into the inner voids of CFC, which fully exploits the effect of CFC as a 3D current collector in governing the plating/stripping behaviors of Li. As a result, the full cell using the GO modified CFC as the negative electrode and NCM811 positive electrodes can maintain 80% of its initial capacity after 460 cycles at a high current of 0.5C charge and 1C discharge. An all-carbon 3D current collector with vertical electro-conductivity differences is prepared by coating a thin graphene oxide layer on the surface of carbon fiber cloth to avoid the "top-growth" phenomenon of Li metal. [Display omitted] • A layer of graphene oxide is assembled on carbon fiber cloths by electrophoresis. • The 3D current collector inhibits "top-growth" phenomenon of lithium metal. • A long lifespan of 460 cycles is achieved in a full cell. [ABSTRACT FROM AUTHOR]

Intercalation of very long molecules into the structure of multi-layered graphene oxide (GO) was studied using example of 1-hexadecanol (C16), an alcohol molecule with 16 carbon atoms. Brodie graphite oxide (BGO) immersed in excess of liquid C16 just above the melting point shows expansion of c-unit cell parameter from ∼6 Å to ∼48.76 Å forming a structure with two densely packed layers of C16 molecules in a perpendicular orientation relative to the GO planes (α-phase). Heating of the BGO-C16 α-phase in excess of C16 melt results in reversible phase transition into β-phase at 336–342K. The β-phase shows much smaller unit cell parameter of 29.83 Å (363K). Analysis of data obtained using vacuum-driven evaporation of C16 from the β-phase provides evidence for structure of β-phase consisting of five layers of C16 molecules in parallel to GO plane orientation. Therefore, the transition from α-to β-phase corresponds to change in orientation C16 molecules from perpendicular to parallel relative to GO planes and decrease in the amount of intercalated solvent. Cooling of the β-phase in absence of C16 melt is found to result in the formation of γ-phase with inter-layer distance of ∼26.5 Å corresponding to one layer of C16 molecules intercalated perpendicularly relative to the GO planes. Structures with one and two layers of C16 molecules parallel to GO planes were identified in samples with rather small initial loading of C16. Surprisingly rich variety of structures revealed in the BGO-C16 system provides opportunities to create materials with precisely controlled GO inter-layer distance. [Display omitted] • Intercalation of Brodie graphite oxide (BGO) immersed in 1-hexadecanol just above its melting point is found to result in a structure with extremely large lattice expansion (∼6 Å to ∼49 Å). • The structure of α-phase corresponds to intercalation of 2 layers of 1-hexadecanol in orientation approximately perpendicular relative to graphene oxide (GO) planes. • Reversible phase transition between α-phase (∼49Å) and β-phase (∼ 30Å) is found for BGO immersed in excess of 1-hexadecanol upon heating/cooling. • The transition from α-to β-phase corresponds to incongruent melting and change in orientation of intercalated 1-hexadecanol molecules. • Several other phases with smaller amount of intercalated alcohol molecules were observed using vacuum –driven removal of melt. [ABSTRACT FROM AUTHOR]

High-performance graphene fiber with intriguing functionality and mechanical strength is expected for wide potential applications. However, it still demands reliable means to realize the rapid wet-spinning of highly aligned fibers because of the insufficient gel strength of graphene oxide (GO) dope and the possible structural imperfections in the obtained fibers. Here, we demonstrate the fabrication of highly conductive and strong graphene fibers by regulating the rheology and spinnability of trace-carbonyl GO dispersion with silk fibroin (SF). The amphiphilic SF can form hydrogen bonds and π-π interactions with GO sheets to significantly enhance the gel strength of spinning dopes, enabling the conformation adjustment and sheet alignment under large drawing ratio and performance enhancement of the GO/SF fibers. After a chemical reduction, the highly orientated and stacked structure endows the fibers with an exceptional tensile strength of 938.6 MPa and a high electrical conductivity of 1501.7 S cm−1. Even more, the conductivity can be further increased to 2700.7 S cm−1, which is among the highest values for chemically reduced GO fibers. This work offers a promising method to produce strong, flexible, and robust graphene fibers for versatile applications in multifunctional fabrics, energy conversion, and health protection areas. We demonstrate the fabrication of conductive and strong graphene fibers reinforced with silk fibroin (SF). The strong interfacial interactions enhance the gel strength of spinning dope and help form compact and orientated structure, giving an exceptional strength of 938.6 MPa and an electrical conductivity of 1501.7 S cm−1. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of flexible supercapacitors (SCs) with high energy density, excellent deformation and cycling stability has great meaning for flexible electronic. Herein, polyaniline array@carbon nanotubes/partially reduced graphene oxide hybrid fiber (PANI@CNT/PRGO) was rationally designed and fabricated. The PANI array were vertically and uniformly grown on CNT/PRGO fiber by controlling the nucleation sites on the fiber. This unique structure enabled the ion to rapid diffusion and the electron to fast transport and sufficient utilization of active sites. The strong interfacial interaction between PANI and CNT/PRGO fiber can reduce the risk of PANI shedding from the fiber during mechanical deformation and long-term cycling. As a consequence, a fiber-shaped SC fabricated by PANI@CNT/PRGO fiber can deliver high volumetric capacitance of 50.2 F cm−3 at a current density of 60 mA cm−3 with 62.5% capacitance retention at 2000 mA cm−3. More encouragingly, the device not only possesses outstanding flexibility and deformation stability (Retention 96.6% after 2000 bending cycles) but also owns prominent long-term stability (Retention 95.8% after 20,000 cycles). Furthermore, the device can yield an outstanding energy density up to 6.97 mWh cm−3. This findings may carve out a new path for regulating the nucleation sites to control the distribution of nanomaterials on graphene fiber, thus obtain hybrid fiber electrodes with outstanding electrochemical performances. [Display omitted] [ABSTRACT FROM AUTHOR]

Metal-free catalysts for hydrogenation reactions using molecular hydrogen (H 2) are a major challenge in the field of catalysis. The Frustrated Lewis Pairs (FLPs) systems and heteroatom-doped carbon materials as metal-free catalysts are currently the mainstream research in hydrogenation reactions. Here, a series of oxygen-induced zigzag graphene (OZG) was constructed over thermal treatment of reduced graphene oxide (rGO) and applied as metal-free catalysts in nitrobenzene hydrogenation. The OZG-800 (thermal treatment at 800 °C) shows promising performance activity with 99.7% nitrobenzene conversion and 94.4% selectivity to aniline. The experimental results indicate that the zigzag edge and medium-strong acid sites formed by oxygen species may be the active centers in nitrobenzene hydrogenation. The density functional theory (DFT) calculations are in accord with experimental results that the zigzag edge and oxygen species play a critical role in H 2 activation and dissociation. This work provides a promising route for the rational design of metal-free catalysts for hydrogenation. Oxygen-induced zigzag graphene was constructed over thermal treatment of reduced graphene oxide and applied as metal-free catalysts in nitrobenzene hydrogenation. The catalyst shows promising performance activity with 99.7% nitrobenzene conversion and 94.4% selectivity to aniline. [Display omitted] [ABSTRACT FROM AUTHOR]

Oxygen functional groups (OFGs) in graphene oxide (GO) are responsible for its different properties and peculiar reactivity in water and different solvents. A detailed assignment, both theoretical and experimental, of OFGs is still missing, and a full reconstruction of GO electrochemical behavior remains unreached. The spatial localization of OFGs is expected to play an important role in the reduction process, but so far, this important aspect remains undisclosed in the literature. Here, the nature and interactions of adjacent OFGs have been investigated, shedding light on the energetics of their electrochemical reduction. GO chemical modifications upon modulated and controlled electrochemical reduction conditions have been studied, in order to excite and reveal the contribution from single reactive OFGs. The characterization has been conducted via X-ray photoelectron spectroscopic analysis supported by theoretical modelling, to compose a detailed picture of the various local environments participating to the rich chemistry of GO. As a result, the interplay between XPS, cyclic voltammetry and DFT computation allowed for a consistent parallel assessment of both the C 1s ionization energy and the electrochemical reduction potential of the various carbonaceous species of GO. [Display omitted] • Raman and XPS on graphene oxide were concerted with electrochemical reduction tests. • DFT helped the assignment of ionization (XPS) and electrochemical reduction (CV) features. • Spatial localization and mutual interactions of functional groups was addressed. • A significant advancement in the interpretation of C 1s XPS spectrum of GO was made. • A significant progress in the interpretation of electrochemical reduction of GO was made. [ABSTRACT FROM AUTHOR]

Understanding the effect of grain size on the overall electrical and thermal transport properties of PRGO films on a large scale is not only fundamental but also technologically important in order to tune their properties for wide applications. In this work, by adjusting the annealing temperature, we control the density of the oxygen containing functional groups and thus the structural domain size of PRGO film. The annealing effect on the temperature dependency of thermal and electrical transport is studied. In addition, the linear relationship between thermal diffusivity and electrical conductivity is confirmed from 320 K to 10 K. The temperature dependent thermal diffusivity of the amorphous region in PRGO is reported. In the last, based on the residual thermal reffusivity at 0 K limit, the structure defects induced phonon mean free path against the annealing temperature is obtained, and compared with the cluster size calculated from XRD, TEM and Raman. A linear relationship among the structure domain size, thermal diffusivity, and electrical conductivity is further revealed, which demonstrates the strong effect of structure domain size on the thermal and electrical transport of PRGO. [Display omitted] • A linear relationship between the thermal diffusivity and electrical conductivity from 320 K to 10 K is reported in PRGO films with varying reduction level. The corresponding mathematical model is proposed. • The electrical transport is found to vary with the thermal reduction level, where the temperature coefficient of resistance (TCR) decreases as the annealing temperature increases, reflecting a tunable band gap. • Based on the residual thermal reffusivity at 0 K limit, the structure defects induced phonon mean free path against the annealing temperature is obtained, and compared with the cluster size calculated from XRD and Raman. • A linear relationship among the structure domain size, thermal diffusivity, and electrical conductivity is further revealed. [ABSTRACT FROM AUTHOR]

In this work, a new approach to the synthesis of lignin-derived nanocarbon crystals based on lignin depolymerization is proposed. The lignin chemical structure was modified through a controlled routine, which was based on sequential UV light irradiation, hydrothermal carbonization in autoclave, vacuum degassing, pyrolysis and mechanical exfoliation. In this way, we were able to obtain a lignin-based nanocarbon with a sp2-hybridized nanoporous framework structure with oxygenated functional groups attached to this structure. The used catalyst-free route resulted in high nanocarbon yields and turns out to be an eco-friendly strategy of a synthesis of low-cost carbon materials. The characterization of the lignin-derived nanocarbon was carried out using X-ray diffraction measurements, infrared, Raman and X-ray photoelectrons spectroscopies analyses. The nanocarbon materials' morphology was evaluated by scanning and transmission electron microscopy. The method of lignin's transformation developed in this work showed itself as a promising alternative for provision of large amounts of carbon-based materials for industrial applications. The proposed approach may be adapted to various biomass feedstocks with aromatic groups' content suitable for their high yield polycondensation. The achieved nanocarbon yield, when starting from a commercial purified lignin, varied between 50 wt% and 70 wt%. [Display omitted] • Lignin raw-material as a carbon source to produce lignin nanocrystals. • Catalyst-free synthesis turns out to be an eco-friendly strategy. • Synthesis provides high output: 50 wt% and 70 wt% yield. • Methodology resulted in an integral conversion of lignin in a nanocarbon. • Carbon sheets forming pores with the size within micropore and low mesopore ranges.. [ABSTRACT FROM AUTHOR]

Herein, we present a potential approach for the qualitative production of quasi-defect-free reduced graphene oxide (QrGO) with semimetallic transport behavior. In rGO, the formation of defects is highly dependent on the oxidation process of graphite. Subsequent exfoliation of graphite oxide, the quasi-defect-free graphene oxide (QGO) shows abundant epoxy and hydroxyl groups which confirmed the suppressed structural deformation. Typical rGO and QrGO are compared to characterize the remarkable electrical, optical, and thermal properties of QrGO. In particular, under low temperature, the unusual carrier transport phenomena of QrGO exhibits a metal-like behavior, unlike typical rGO, which shows an insulator-to-semimetal transition with variable-range hopping conduction behavior. This conduction mechanism, resembling that of mechanically exfoliated graphene, facilitates the fabrication of a QrGO-based conducting film with a high electrical conductivity of ∼1000 S/cm. Moreover, during a 200-h test with temperature and moisture conditions of 85 °C and 85%, respectively, QrGO shows environmental stability with minimal fluctuations in resistance. Furthermore, a conducting paste was fabricated from QrGO in an aqueous solution, showing a highly concentrated solid content and excellent electrical conductivity. It shows great potential for the large-scale production of high-quality chemically exfoliated graphene for practical applications. A promising approach for the high-quality scalable production of QrGO is proposed. The remarkable electrical, optical, and thermal characteristics of QGO and QrGO are examined, showing a semicrystalline graphene structure. The transport phenomena exhibit a metal-like behavior, resembling that of mechanically exfoliated graphene, unlike the variable-range hopping behavior of general rGO. The electrical conductivity of QrGO is considerably high at almost 1000 S/cm. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon fibers, which are known for their high strength to weight ratio and thermal and chemical stability, are key components in advanced structural composites. Controlling the fiber-matrix interface is key to achieving required physical performance. Functional two-dimensional (2D) materials that can conformally coat the fiber surface facilitate interface and interphase engineering for enhanced mechanical properties and added functionalities. Understanding how 2D flakes bond, integrate, and perform at carbon fiber interfaces is key to developing multifunctional high-strength composites. In this study, we focus on the surface interactions of graphene oxide (GO) and Ti 3 C 2 T x MXene nanoflakes at the surface of low-tension carbon fibers with and without amine functionalization by in-depth multimode scanning probe microscopy. We suggest that beyond strengthening the interfaces, GO and MXene provide efficient charge transfer with MXene also adding conductivity to the fiber surface, extending potential applications of composites to broad areas including structural supercapacitors and battery cooling/packaging materials. GO and MXene modified fibers not only create opportunities for increased interfacial adhesion in composites via increased surface roughness, but also act as anchors for bonding, energy dissipation, charge transport, and local interface stiffening. [Display omitted] [ABSTRACT FROM AUTHOR]

A reduced graphene oxide (rGO) film is mechanically fragile; therefore, transferring it to another substrate without damage is crucial. Hence, a technique that facilitates the formation of an integrated rGO film that holds adhesion with the substrate is desired. Moreover, a rGO film on metal is promising as an electrode for energy storage devices. This work presents the formation of rGO film on copper using electrophoretic deposition (EPD) and flash sintering. Briefly, a stable aqueous dispersion of graphene oxide (GO) layers was used to form a uniform GO film on copper at a fixed deposition voltage and time duration. To reduce the GO film without detaching it from copper, pulse energy (1–10 J cm−2) was varied for a fixed exposure time (10 ms) and a single micropulse. At pulse energy of 6 J cm−2, the structural studies indicated turbostratic stacking (decreased interlayer spacing) and restored crystallinity (decreased peak intensity ratio of D and G bands). The morphology showed voids between stacked rGO layers and high roughness in the film. The reduction resulted in mesoporous and high surface area (373 m2 g−1) multilayer rGO film. Due to restored electrical conductivity, the rGO film showed a specific capacitance of 475.8 F g−1 at a scan rate of 2 mV s−1. An increase in contact angle from ∼66° to ∼81° also validated the reduction. The combination of EPD and flash sintering offers rapid and eco-friendly formation of binder-free rGO film on copper, promising as an electrode for supercapacitors. [Display omitted] • Facile formation of reduced graphene oxide (rGO) electrodes using electrophoretic deposition (EPD) and flash sintering. • The rGO electrode on copper exhibits high surface area, mesopores, and excellent electrical conductivity. • Rapid, clean, and environmentally benign production of thick and multilayer rGO electrodes. • The rGO electrodes are promising as an electrode for energy storage devices. [ABSTRACT FROM AUTHOR]

The unique characteristics and low cost of graphene oxide (GO) make it a promising nanocarbon material for many practical applications. However, despite intensive studies with advanced spectroscopic and microscopic methods as well as theoretical calculation, the two-dimensional structure of GO remains controversial due to the structural complexity, inhomogeneity, and instability. Here, we employed a synchrotron in-plane X-ray diffraction (XRD) technique to elucidate its true 2D structure. An overall feature of the in-plane XRD profiles of GOs obtained by Hummers' and Brodie's methods revealed that the graphene-like hexagonal lattice was preserved without amorphization after severe chemical oxidation. The 10 reflection peak was analyzed to probe the intraplane lattice expansion, shrinkage, and microstrain that depend on the oxidation and reduction conditions due to the interconnected oxygen functional groups and carbon defects in a single crystalline domain. Based on the correlation between the global and local structures and the chemical composition, we established a three-step reduction process of GO consisting of deoxygenation, diffusionless lattice modification, and diffusional lattice modification. The updated 2D structural model and the generalized reduction process will facilitate the design and interpretation of GO-related materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The fluorination of self-standing graphene oxide (GO) films under mild conditions at 70 °C for 1h using a mixture of elemental fluorine and nitrogen gases (0.35 F 2 /0.65 N 2 v/v) results in transparent, highly fluorinated (F/C = 1 as seen by XPS) graphene oxide (FGO) films which maintain initial densely packed structure and mechanical strength. Most of the oxygen atoms in the GO film were replaced by fluorine after fluorination, and two types of carbon-fluorine bonds coexist, i.e. primarily weakened C⋯F bonds and also pure covalent C–F bonds as evidenced by FTIR, XPS, NMR, and cyclic voltammetry when FGO is used as electrode in Li/electrolyte (PC:EC:3DMC/LiTFSI 1 M)/FGO cell similar to a lithium battery. To further understand the fluorination mechanism and to distinguish the reaction steps, xenon difluoride XeF 2 was used as fluorinating agent for GO and in situ EPR and FTIR analyses suggest hydroxyl groups as preferential reactive sites. These self-standing transparent FGO films exhibit unusual electrochemical properties in lithium battery and can be used as hydrophobic lubricant membranes because of the low and stable coefficient of friction evidenced in the present work. [Display omitted] [ABSTRACT FROM AUTHOR]

In the processing of two-dimensional (2D) liquid crystal (LC), the microstructure of 2D LC colloids is continuously deformed by shearing, which ultimately determines their physical properties. However, it is experimentally difficult to investigate and visualize how the microstructure continuously changes during processing involving shear stress. Thus, controlling the microstructure of 2D LCs using shear forces remains a more difficult problem. Herein, we report the in-situ analysis of structural deformation for 2D colloids liquid crystals focused on the reorientation of the liquid crystal (LC) under oscillatory shear. Graphene oxide (GO) was employed as a model system for 2D LC colloids, and polymers were added to control the 2D colloidal interactions. We found that the GO structure deforms in two steps: The first step is the transition to multi-domains of GO LC and the second transition brings the macroscopic alignment of GO. We additionally found that the added polymer causes the earlier disappearance of multiple GO LC domains and provides a better macroscopic alignment at the same shear condition. The study will be of great interest in the 2D colloidal process accompanying yielding behavior, providing an effective strategy to control the domain orientation and the resulting properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene-enhanced Raman scattering was an attractive Raman enhanced technique and has made remarkable progress in food safety, environmental monitoring, and bioanalysis. However, novel three-dimensional (3D) graphene materials had not been explored as SERS substrates. Here, 3D graphene oxide aerogels (GOA) were constructed and used as ultra-sensitive SERS substrates. In a hydrothermal environment, GO nanosheets were self-assembled into GO hydrogel and then combined with freeze-drying to obtain GOA. The optimized GOA had a high SERS enhancement factor (3.1 × 104) and a low detection limit (10−8 M) for the dye molecules. The excellent SERS effect was attributed to the large specific surface area of GOA, which facilitated molecular adsorption and formed abundant 3D hot spots. In addition, benefiting from the electron transfer promoted by the reduction of the band gap energy, synergistically enhanced the SERS effect. This work expands the applications of graphene oxide aerogels and provides valuable insights for designing novel 3D SERS substrates. Graphene oxide aerogels (GOA) are constructed via hydrothermal self-assembly methods and used as ultra-sensitive SERS substrates. The large specific surface area of GOA facilitates molecular adsorption and form abundant 3D hot spots. Besides, the content of oxygen-containing functional groups and electrical conductivity is the key role for excellent SERS effect. [Display omitted] [ABSTRACT FROM AUTHOR]

Marine biological fouling is the undesirable accumulation on the surfaces of submerged objects and causes environmental and economic consequence to ships and marine facilities. However, traditional coatings achieve antifouling by releasing toxic heavy metal antifouling agents, causing ecological problems. And the static antifouling performance of self-polishing antifouling coating is not good. To overcome the shortcoming, a novel antifouling strategy to build a self-renewing multi-level microstructure on the coating surface was developed by dispersing GO-based quaternary polymer brushes in a self-polishing fluoro/silyl acrylate copolymer. Quaternized GO exhibits excellent dispersibility in the silyl-based acrylate copolymer. A dynamic self-renewing surface is realized for the coating via a self-polishing effect that exposes the filler inside the coating at the surface. The multi-level microstructure of the sharp edge of GO and quaternized "spear" structure destroys the cell wall of organisms. And a "water-shield" on amphoteric ion surface on quaternized GO inhibits adhesion of organisms. The antibacterial and anti-algae tests demonstrated the excellent antifouling effect of the coating at only 0.1% (mass) filler content, with anti-algae ratio against Nitzschia closterium (N. closterium), Phaeodactylum tricornutum (P. tricornutum) and Halamphora sp. of 83.7%, 52.4%, and 65.8%, respectively. The proposed preparation method is simple and potentially applicable to large-scale production for antifouling application. [Display omitted] • Multi-level microstructure was constructed for antifouling by quaternization-modified GO. • The coating exhibited a significant antifouling effect at only 0.1% (mass) filler content. • A GO surface killing-resistance mechanism is proposed for the first time. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is a promising solid lubricant for moving mechanical systems to implement reliable and effective lubrication due to its easy modification and excellent tribological properties. However, obtaining highly dense GO coatings simultaneously with high hardness and extensibility is still a challenge for available self-assembly techniques, and these characteristics are beneficial to tribological properties. Inspired by the advanced abrasion resistance system of mussel byssus threads, a surprisingly simple and versatile metal ions (namely Fe2+ and Fe3+ ions) directed self-assembly strategy has been developed to rapidly fabricate GO coatings. GO as a solid lubricant is highly sensitive to the interface structure and test environment. Consequently, the influence of the valence state of iron ions on the macroscopic tribological properties of GO-based coatings in air, nitrogen gas and vacuum environments are comparatively investigated. The results show that the GO-Fe3+ coating with a highly compact characteristic and unique granular microarchitecture resulting in higher hardness and strain capacity displays a lower friction coefficient and remarkable wear resistance than the GO-Fe2+ coating. Additionally, because water molecules generate strong hydrogen bonding gradually disrupting the ordered layered structure, both GO-Fe2+ and GO-Fe3+ coatings exhibit a higher friction coefficient in air than in nitrogen gas and vacuum. [Display omitted] • Graphene oxide coatings with enhancing mechanical properties and tribological properties via chemical cross-linking are made by a facile and versatile bioinspired iron ions induced self-assembly strategy. • Compared with GO-Fe2+ coating induced by Fe2+ ions, stronger affinity ability between GO nanosheets and Fe3+ ions are prone to achieve much compact GO-Fe3+ coating. • GO-Fe3+ coating with unique granular micro-architecture resulting in higher hardness and strain capacity displays superior tribological properties than GO-Fe2+ coating. • GO coatings have superior tribological properties in dry nitrogen gas and vacuum environments than that in humid air environments due to their easier to form orderly layered structures. [ABSTRACT FROM AUTHOR]

Carbon coating has been an effective procedure to tackle the severe structural degradation and poor conductivity during cycling of silicon-based anodes in lithium-ion batteries (LIBs). However, the traditional coated carbon usually is tight and thus limit the fast-charging rate and high specific capacity. Herein, through in-situ formation of metal-organic frameworks on the surface, silicon particles were firstly coated by an inside carbon layer. Followed by a solvothermal reaction with the mixture of sucrose and graphene oxide, the second carbon layer outside the silicon particles was deposited, and simultaneously a highly conductive graphene network was formed. After a high temperature pyrolysis process, a graphene matrix supported silicon material with inward multi-channel carbon and outward tight activated carbon was prepared. This unique core/double-layer carbon structure, combined with the highly conductive graphene frameworks, render the material to demonstrate excellent electrochemical performance as anode materials for LIBs in terms of both lithium storage capacity and cycling stability. Thus, the electrode materials deliver a high specific capacity of 1528.1 mA h g−1 at the current density of 0.1 A g−1 and rate capacity retention of 45.5% at 1 A g−1 to 0.1 A g−1. Simultaneously, a highly stable reversible capacity of 1182 mAh g−1 with 89.5% retention over 240 cycles at a current density of 0.2 A g−1 and 484 mAh g−1 with 76.8% retention after 450 cycles at 1.0 A g−1 were obtained. This work can offer an alternative approach for high-energy and low-cost silicon-based anodes for LIBs. A Graphene/IOC@Si LIB anode nanomaterial with controlled and optimized morphologies and microstructures, taking of MOF derived inner carbon layer with adequate channels for the electron and ion transportation, sucrose derived outer carbon layer with capability for restraining the volumetric effect of silicon nanoparticles, as well as graphene matrix with excellent conductivity was obtained. The electrode materials deliver a high specific capacity of 1528.1 mA h g−1 at the current density of 0.1 A g−1 and rate capacity retention of 45.5% at 1 A g−1 to 0.1 A g−1. Simultaneously, a highly stable reversible capacity of 1182 mAh g−1 with 89.5% retention over 240 cycles at a current density of 0.2 A g−1 and 484 mAh g−1 with 76.8% retention after 450 cycles at 1.0 A g−1 were obtained. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene, with an extremely high intrinsic thermal conductivity of 5300 W/mK, is of special interest to meet thermal requirements in future wearable and high-power electronic devices. Generally, microscopic graphene sheets can be built into a macroscopic material by using graphene oxide (GO) as the precursor. However, both the defects on the basal plane of GO sheets and the lack of connections at their boundaries induce massive scattering of phonons and a low thermal conductivity. Herein, we solve the problem through the nanoarchitectonics of GO with nano Fe 3 O 4 functionalized cellulose nanocrystals (Fe–CNC). During the assembly process, Fe–CNC were compounded with GO homogeneously and formed a composite GO/Fe–CNC film with an aligned lamellar structure. A subsequent thermal reduction at 1500 °C resulted in the generation of Fe/Fe 3 C nanoparticles in the matrix of the reduced GO/Fe–CNC. During this process, the reduced GO (R-GO) sheets were dually connected by the Fe/Fe 3 C nanoparticles as well as the carbonized cellulose nanocrystals. Furthermore, the defects on the R-GO are repaired by Fe through a catalytic graphitization process. Thus, the scatterings of phonons at the adjacent sheet boundaries and on the basal plane of the R-GO sheets were reduced. A flexible and light weight composite film of reduced GO/Fe–CNC with a thermal conductivity of 1958.14 W/mK was obtained. The thermal conductivity is much higher than that of a pure R-GO film (388.72 W/mK) prepared under the same conditions. This assembly process achieved dual connections and defect repairs simultaneously and it provides an avenue for the design of graphene-based films with a high thermal conductivity. [Display omitted] • An assembly method is developed for the fabrication of GO/Fe–CNC composite films with an aligned lamellar structure. • The R-GO sheets were dually connected by the Fe/Fe 3 C nanoparticles as well as the carbonized CNCs. • The defects on the R-GO can be repaired by the generated Fe through a catalytic graphitization process. • The R-GO/Fe–CNC film presents a much high in-plane thermal conductivity of 1958.14 W/mK, higher than that of a R-GO film. [ABSTRACT FROM AUTHOR]

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 (TiO 2 -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 TiO 2 -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. A renewable graphene-based FET biosensor for cellular Ca2+ detection. [Display omitted] [ABSTRACT FROM AUTHOR]

This work details the synthesis, materials characterization and absorption capacity of graphene aerogel (GA) loaded with UiO-66-NH 2 metal organic framework (MOF). A series of density-tunable MOF/GA composites were synthesized by adjusting the MOF/graphene oxide (GO) mass ratio of the precursors before hydrothermal reduction and subsequent critical point drying to achieve MOF- x %/GA composites, with x, ranging from 0 to 100, denoting the weight percent ratio of MOF to GO in the starting solution. Scanning electron microscopy (SEM) images and Barrett-Joyner-Halenda (BJH) pore size calculations supported that MOF loading enlarged the macroporous (>50 nm) structure of the GA framework but had no influence on the mesoporous (2–50 nm) structure of GA. The degree of MOF loading first decreased and then increased the density of resulting composites, exhibiting a minimum for the 10–30% samples. Such behavior with respect to MOF loading has not been reported previously. MOF- x %/GA samples were further investigated for absorption capacity using various organic liquids. MOF-30%/GA proved to be the best absorbent sample for all solvents tested, achieving the highest capacity for chloroform at 147.0 ± 10.0 mg/mg. The behavior is attributed to the structural changes induced by the MOF incorporation as well as the interactions between the organic molecules and the MOF. [Display omitted] [ABSTRACT FROM AUTHOR]

Sealing treatment is an effective method to prolong the service life of Fe-based amorphous coatings for steel substrates. Common sealants always have the disadvantages of releasing amounts of volatile organic compounds (VOC) and are expensive, prompting researchers to develop an eco-friendly, low cost and high-performance sealant. However, their simultaneous improvement is restricted by some inevitable contradictions among them. Herein, natural rosin was introduced as a sealing material and an eco-friendly natural rosin-based SiO 2 –NH 2 @GO hybrid sealant was successfully prepared by the sol-gel method. In addition, the functional nanocomposite SiO 2 –NH 2 @GO was added to the hybrid sealant system to achieve the purpose of extending the service life of the sealant. The filling efficiency, adhesion, thermal stability and long-term corrosion resistance of hybrid sealants were investigated. The study showed that the adhesion of the hybrid sealant to the Fe-based amorphous coating was improved by 10.59% after adding the nanocomposite. The hybrid sealant reaches maximum thermal decomposition at 414.3 °C. The corrosion current density (i corr) of the sample NSG-0.5‰ still decreased by about two orders of magnitude after immersion for 672 h (0#, i corr = 1.39 × 10−4 A/cm2; NSG-0.5‰, i corr = 1.51 × 10−6 A/cm2). Full immersion experiments explore the failure process of hybrid sealants, where corrosion always tends to propagate with unmelted particles. The hybrid sealant prepared has the advantages of being eco-friendly and low cost, and provides a specific preparation process, which provides a new direction for the development of the sealant. The preparation process of nanocomposite SiO 2 –NH 2 @GO and sealed samples. [Display omitted] [ABSTRACT FROM AUTHOR]

Na-titanate is a class of potentially 'safe' anode material for Na-ion batteries, with the combination of Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 , as 'Bi-phase NTO', often performing better than the single-phase counterparts. Nevertheless, good coverage and intimate contact of the Na-titanate particles with conducting reinforcements is needed for achieving superior electrochemical performance by suppressing deleterious reactions with electrolyte and providing connectivity across particles. Against this backdrop, the present manuscript reports on the effects of dimensionality, functional groups and conductivity of carbon-based reinforcements [ viz. , pristine and functionalized multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide, carbon black] towards the performances of 'Bi-phase NTO'/carbon-based electrodes. High aspect ratio, along with the presence of functional groups, of functionalized MWCNTs results in complete coverage/'wrapping' of Na-titanate surface; thus, leading to the best improvements of Na-storage capacity and cyclic stability of 'Bi-phase NTO', along with negligible increment in impedance over electrochemical sodiation/desodiation cycles. Nevertheless, higher overall electronic conductivity bestowed by the less defected and less functional group containing pristine MWCNT leads to the best rate-capability. However, carbon black, lacking in terms of both aspect ratio and presence of functional groups, and leading to a very poor coverage of the Na-titanate surface, does not improve the electrochemical performances of 'Bi-phase NTO'. [Display omitted] [ABSTRACT FROM AUTHOR]

Based on the rational component regulation and micro-nano structure design, hierarchical dielectric-magnetic microspheres become the ideal functional materials in the microwave absorption field. Herein, unique three-dimension (3D) Co/CoO/reduced graphene oxide (RGO) (denoted as CCOR) microspheres with the hierarchical structure are prepared by a simple solvothermal method and annealing treatment. Due to the plentiful growth sites on the surface of graphene oxide, Co/CoO nanoparticles (NPs) homogeneously anchor on the RGO. Meanwhile, larger size Co/CoO particles connect 2D RGO nanosheets to form the hierarchical CCOR microspheres, which introduce abundant heterojunctions and interfaces. The electromagnetic parameters have been effectively adjusted by tuning the synergistic effect between the magnetic Co/CoO particles and highly conductive RGO nanosheets. The obtained CCOR composites exhibit excellent microwave absorption performance with the maximum reflection loss (RL max) of −50.1 dB. The effective absorption bandwidth reaches 6.56 GHz covering the whole X-band frequency. The outstanding microwave absorption performance of CCOR microspheres stems from the followings: i) well micro-nano structure design provides abundant heterojunction interfaces, resulting in the enhanced interfacial polarization; ii) the magnetic-dielectric synergistic loss ability from rational Co/CoO and RGO component design, facilitating the microwave energy dissipation; iii) the Co/CoO particles induce multi-scale magnetic coupling effect and strengthen the magnetic response capability. Thus, as-synthesized Co/CoO/RGO microspheres demonstrate the huge potential for application of stealth in X band as microwave absorption materials. The three-dimension (3D) hierarchical core-shell Co/CoO@Co/CoO/RGO microspheres with novel conductive network exhibited excellent magnetic-dielectric synergistic effect, strong reflection loss and ultrabroad bandwidth covering the whole X-band. [Display omitted] • Unique three-dimension Co/CoO/RGO microspheres with the hierarchical structure are obtained by simple method. • Abundant interfacial polarization and multi-scale magnetic coupling effect contribute to the magnetic-dielectric synergy. • The MA properties can be easily tuned just by tailoring the input amount of GO. [ABSTRACT FROM AUTHOR]

NiFe 2 O 4 takes an attractive potential candidate for oxygen evolution reaction (OER) catalysts, however, its usual preparation based on high-temperature calcination limits exposure of catalytically active sites. Herein, we report a new and efficient strategy for preparing NiFe 2 O 4 supported by three-dimensional graphene network (NFO/3DGN) electrocatalysts. Specifically, NiFe layered double hydroxide (NiFe LDH) was exfoliated to single layer by polylactic acid (PLA), single layer NiFe LDH was released when PLA was hydrolyzed, and PLA hydrolysate etched single layer NiFe LDH to NiFe 2 O 4 ; Meanwhile, the lamellar graphene oxide was reduced to 3DGN, so that NiFe 2 O 4 was loaded on 3DGN, which means the agglomeration of NiFe 2 O 4 could be prevented and efficient electron transmission channels for NiFe 2 O 4 could be provided due to 3DGN. The as-prepared NFO/3DGN-10 exhibited an excellent electrocatalytic activity and stability for OER in an alkaline solution (with a low overpotential of 272 ± 25 mV at 10 mA cm−2 with a Tafel slope of 64 mV dec−1). Based on theoretical calculations, the reaction energy barrier of NiFe 2 O 4 on the speed determination step reduced significantly owing to 3DGN. These results indicate that this facile fabrication method is a promising route for developing high-performance catalysts based on mixed metal spinel oxides supported by 3DGN. NiFe 2 O 4 is evenly dispersed on the three-dimensional graphene network formed by rGO, which is conducive to the full exposure of the catalytic site, and rGO can improve the smooth electron transport channel in the electrocatalytic OER process. [Display omitted] • Single layer NiFe LDH is directly converted to NiFe 2 O 4 under hydrothermal conditions. • NiFe 2 O 4 is uniformly loaded on the three dimensional network structure formed by rGO. • The NFO/3DGN nanocomposite shows an outstanding performance for OER. • Offer a new strategy of preparation mixed metal spinel oxides for OER catalysts. [ABSTRACT FROM AUTHOR]

The development of structure-function integrated materials is an important trend in military field. How to achieve the enhanced interfacial property and electromagnetic interference (EMI) shielding property of carbon fiber (CF) reinforced polymer (CFRP) simultaneously is the main challenge at present. Herein, the mechanically strengthened CFRP with superior EMI shielding property was developed by the introduction of reduced graphene oxide/Fe 3 O 4 , i.e. , RGF into epoxy resin, combined with CF modified by uniform polyaniline (PANI) shell. The interlaminar shear analysis indicated that the RGF nanofiller in resin matrix and uniform PANI shell on CF could effectively optimize the interlaminar shear behavior due to the enhanced cohesive strength and adhesion strength among interface phase. Notably, the resultant composite achieved an interlaminar shear strength of 80.4 MPa, 37.4% higher than that of virgin CF/epoxy composite. Additionally, thanks to the excellent electromagnetic wave loss of RGF as well as the unique alternating multilayer, the super EMI shielding effectiveness of 78.5 dB with was achieved when the RGF content was 4.0 wt%, much higher than 34.7 dB of virgin CF/epoxy composite. The excellent interlaminar shear and EMI shielding behaviors endow the composite with potential application in military field, which providing a new strategy for the development of high-performance CF/epoxy composite. [Display omitted] • PANI and reduced graphene oxide/Fe 3 O 4 were introduced to improve the adhesion strength and cohesive strength of composite. • The carbon fiber/epoxy composite showed a superior electromagnetic interference shielding effectiveness of 78.5 dB. • The carbon fiber/epoxy composite exhibited excellent mechanical properties, with an interlaminar shear strength of 80.4 MPa. • An interfacial enhancement mechanism was proposed to explain the excellent interlaminar shear property of the composites. [ABSTRACT FROM AUTHOR]

Hydrogen, generated from water splitting, is postulated as one of the most promising alternatives to fossil fuels. In this context, direct hydrogen generation by electrolysis and fixation to graphene oxide in an aqueous suspension could overcome storage and distribution problems of gaseous hydrogen. This study presents time-resolved determination of the electrochemical hydrogenation of GO by in-situ Raman spectroscopy, simultaneous to original functional groups elimination. Hydrogenation is found favoured by dynamic modulation of the electrochemical environment compared to fixed applied potentials, with a 160% increase of C–H bond formation. Epoxide groups suppression and generated hydroxide groups point at these epoxide groups being one of the key sites where hydrogenation was possible. FTIR revealed characteristic symmetric and asymmetric stretching vibrations of C–H bonds in CH 2 and CH 3 groups. This shows that hydrogenation is significantly also occurring in defective sites and edges of the graphene basal plane, rather than H-Csp3 groups as graphane. We also determined a −0.05 V RHE reduction starting potential in alkaline electrolytes and a 150 mV cathodic delay in acid electrolytes. The identified key parameters role, together with observed diverse C-H x groups formation, points at future research directions for large-scale hydrogen storage in graphene. [Display omitted] [ABSTRACT FROM AUTHOR]

The evolution of advanced supercapacitors depends highly on the design and synthesis of electrodes with rational morphology and structure. In this paper, a facile methanol-assisted solvothermal method is reported for the synthesis of spherical hydrated manganese vanadate (MnV 2 O 6 ·2H 2 O)-reduced graphene oxide (rGO) nanosheets hybrid. In particular, the utilization of methanol can not only change the isotropy growth of MnV 2 O 6 but also suppresses the phase-transformation process (from orthorhombic to monoclinic) by preventing the deintercalation of crystal water. Remarkably, the MnV 2 O 6 ·2H 2 O exhibits a superior specific capacity of 1678.5 F g−1 which is nearly four times more than that of MnV 2 O 6 (410.2 F g−1) at 2 A g−1. After integrating with graphene, MnV 2 O 6 ·2H 2 O spheres are uniformly encapsulated by graphene sheets with a size reduction from 1 μm to 200 nm. And a "GO-assisted Ostwald ripen-splitting" mechanism is proposed to explain the formation of MnV 2 O 6 ·2H 2 O-rGO. Consequently, the MnV 2 O 6 ·2H 2 O-rGO hybrid exhibits significantly improved conductivity, enhanced specific capacity (1976.3 F g−1 at 2 A g−1) and good rate capability (1422.5 F g−1 at 10 A g−1 and 1155.5 F g−1 at 20 A g−1) as well as excellent cycling stability (94.2% capacitance retention after 10,000 cycles). Moreover, the assembled asymmetric supercapacitor using MnV 2 O 6 ·2H 2 O-rGO (the positive electrode) and activated carbon (the negative electrode) shows a superior energy density of 51.5 Wh⋅kg−1 at the power density of 849.2 W kg−1. [Display omitted] • A novel hybrid of spherical MnV 2 O 6 ·2H 2 O and rGO nanosheets was fabricated with a methanol-assisted solvothermal method. • A "GO assisted-Ostwald ripen process" mechanism is proposed to explain the formation of MnV 2 O 6 ·2H 2 O-rGO. • The oxygen containing functional groups of GO guarantee the uniform distribution and size reduction of MnV 2 O 6 ·2H 2 O spheres. • A high specific capacity of 1976.3 F g-1 is achieved at 2 A g-1. • The assembled ASC device delivers a high specific energy of 51.5 Wh·kg-1 within 1.7 V. [ABSTRACT FROM AUTHOR]

Surgical resection of breast cancer bone metastases causes two serious consequences including large bone defects and tumor recurrence risk. Herein, nacre-mimetic graphene oxide/layered double hydroxide/chitosan (GO/LDH/CS) layered scaffolds with appropriate mechanical strengths, excellent anti-tumor and pro-osteogenesis activities were developed for the therapy of breast cancer bone metastases. The bifunctional scaffolds were constructed by the composite films layer by layer using CS as organic matrices and LDH/GO as inorganic fillings. The nacre-mimetic architecture endowed the bone scaffolds with a great compression strength, avoiding the damage of layered macropores during a therapeutic process. The modification of GO photothermal agents made the GO/LDH/CS layered scaffolds have anti-tumor function. Under near-infrared (NIR) light irradiation, the local temperature around the GO/LDH/CS scaffolds rose to 52 °C within 2 min, which was high enough to trigger tumor apoptosis via increasing caspase-3 expression. Moreover, the combined effect of GO nanosheets and Mg2+ ions enhanced the pro-osteogenesis activity of the GO/LDH/CS layered scaffolds. After 12 weeks of post-operation, the layered macropores in the scaffolds were filled with extracellular matrix and bone tissues. Hence, the integration of nacre-mimetic architecture and biofunctional materials may be a novel approach to treat intractable disease-related bone defects. [Display omitted] • GO/LDH/CS layered scaffolds were constructed against breast cancer bone metastases. • Nacre-mimetic architecture showed layered macropores and great compressive strength. • GO photothermal agents enhanced anti-tumor activity of nacre-mimetic scaffolds. • NIR-light irradiated GO/LDH/CS scaffolds induced tumor apoptosis. • GO nanosheets and Mg2+ ions promoted osteogenic differentiation of MC3T3-E1 cells. [ABSTRACT FROM AUTHOR]

Graphene and graphite are generally considered as materials exhibiting friction anisotropy. However, it was demonstrated by friction force microscopy experiments that friction anisotropy most likely originates from adsorbates aligning in well-ordered stripes on graphitic surfaces. In this study, we analyzed the evolution of adsorbates on a few-layer graphene-/graphite-flake on top of a Si/SiO 2 -substrate after different times of storage using a multifrequency force microscopy approach. The method allows for the simultaneous in-plane and out-of-plane sample analysis as well as the discrimination of conservative and dissipative tip-sample interactions directed parallel and perpendicular to the surface and thus offers a myriad of complementary physical information. We found that friction anisotropy was observable at distinct areas of the graphene-/graphite-flake after 14 days of storage when exposed to air, albeit not throughout the whole flake, indicating different types of adsorbates. High-resolution imaging revealed that friction anisotropy occurred not only at positions where stripe-like structures were visible, but also on areas which were completely covered with adsorbates. Additionally, we demonstrated that after removal of the adsorbate material by oxygen-plasma treatment, no friction anisotropy was observable on the graphene-/graphite-flake, corroborating adsorbate driven nature of friction anisotropy on graphitic surfaces. [Display omitted] • Combined in-plane and out-of-plane force microscopy for interpretation of ordered adsorbate formation on graphite/graphene. • Discrimination of different types of adsorbates by tip-sample interactions parallel and perpendicular to the surface. • 90° rotation of the graphene/graphite flake revealed that friction anisotropy is only caused by certain types of adsorbates. [ABSTRACT FROM AUTHOR]

With the broader application of intelligent sensors in various complex conditions, sensing materials with better mechanical and conductive properties as well as higher temperature adaptability are required. For this purpose, a GO/PVA/MXene (GPM) composite aerogel was designed and prepared via a two-step strategy, including self-assembly and vacuum-assisted dip-coating processes. The as-prepared GPM has a unique structure composed of hierarchical GO network skeleton and MXene coating, endowing it with high Young's modulus (11.2 kPa) and compressibility (90%). Demonstrated with the finite element (FE) simulation, the elasticity and toughness of the GPM are originated from the hierarchical microstructure and the improved thickness of shells. Besides, the GPM exhibits a long-term durability of 5,000 compression cycles at 50% strain, a high sensitivity of 1.744 kPa−1, and a rapid response time of 4.5 ms. Further application examples reveal that the pressure sensor based on GPM has superior physiological signal capture capability, realizing fingertip pulse and temporal artery detections. Moreover, the GPM aerogel possesses high thermal insulation efficiency, resulting in good temperature adaptability in harsh environments from −196 °C to 300 °C. The sensitive pressure sensors should have the potential application in many fields of intelligent factories, complex militaries, and space discoveries. A GO/PVA/MXene (GPM) composite aerogel was designed via a two-step strategy, including self-assembly and vacuum-assisted dip-coating processes. The GPM has a unique structure composed of hierarchical GO skeleton and MXene coating, endowing it with high Young's modulus (11.2 kPa) and compressibility (90%). Besides, the GPM exhibits long-term durability of 5,000 compression cycles at 50% strain, high sensitivity of 1.744 kPa−1, and a rapid response time of 4.5 ms. Moreover, the GPM aerogel possesses high thermal insulation efficiency, resulting in temperature adaptability in harsh environments from −196 °C to 300 °C. [Display omitted] • PVA was used to modulate the microstructure of the GO skeleton for obtaining the hierarchical GPM aerogel. • MXene coating endows GPM aerogel with the excellent mechanical and conductive property. • GPM-based sensor exhibits superb detection capability and wide temperature adaptability. [ABSTRACT FROM AUTHOR]

Interfacial solar-driven steam generation as a cost-effective green technology has shown a great potential in realizing water desalination and purification. To achieve high solar steam generation efficiency, it is important to simultaneously realize high solar absorption and effective water transportation. Among various solar absorbers, Janus structures composed of different layered materials for multiple functions have been demonstrated to be promising for high efficiency. However, the complex material composition and the corresponding multistep fabrication process become a barrier for high efficiency realization and large-scale applications. Developing a simple, low-cost, and fast fabrication process holds the key to producing Janus absorbers with high efficiency. Herein, we propose and demonstrate a monolithic Janus absorber fabricated by a single shot flash reduction of an ultrathin (370 nm) graphene oxide film within a millisecond time frame. By synchronising the advantages of a top three-dimensional (3D) porous graphene structure for high solar absorption (99%) and a bottom two-dimensional (2D) layered graphene oxide structure for efficient water transportation, the fabricated Janus absorber achieves high solar-to-vapour conversion efficiency of 94.5% under one sun illumination and steady water production (2.054 kg m−2 h−1). Such a large-scale high yield production method is orders of magnitude faster than the state-of-the-art Janus film fabrication method and offers a highly efficient and reliable approach for solar water desalination and purification. [Display omitted] [ABSTRACT FROM AUTHOR]

The reduction process for graphene oxide (GO) is important for this kind of graphene to be used as a conducting nanomaterial. After encapsulating barium titanate (BTO) powder particles in GO platelets, the GO-encapsulated BTO was chemically reduced with hydrazine (H 2 NN(CH 3) 2) by varying the reduction time (6, 12, 18, and 24 h). Reduced-graphene-oxide--encapsulated BTO (RGO@BTO) fillers were mixed with a polymer matrix, to boost the performance of the dielectric composites with the help of interfacial polarization. All the composite samples with RGO@BTO fillers exhibited substantially higher dielectric constants (52–72%) due to encapsulation, while suppressing dielectric losses. The best dielectric performance was obtained from 18 h (the second longest time) not from 24 h. It can be interpreted that 18 h is a balancing point between the main process of removing oxygen-functional groups and the collateral process of attaching nitrogen-functional groups from a reduction agent of hydrazine. Detailed analyses of XRD, XPS, Raman scattering, and impedance analysis, support the specialty at 18 h. Additionally, AC-driven inorganic electroluminescence devices with RGO@BTO fillers yielded to the best performance at 18 h. Therefore, during the chemical reduction of RGO, optimizing the reduction time is imperative for high dielectric performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon fibers have been manufactured industrially for several decades and are widely used in the construction of aircraft, racing cars or sports appliances et al. However, carbon fiber showing no response and adaptation to environmental stimulation has prevented the widespread use of this excellent mechanical reinforcement as functional material. Here, we demonstrate that carbon fibers have not only excellent mechanical properties but also intelligent properties with color responsiveness. We coated graphene oxide (GO) on carbon fiber surface, where the two-dimensional GO orderly stack together and self-assemble as a lamellar stacked structure. Such self-assemble GO film exhibits structural color since the stacked structure is analogous to one-dimensional photonic crystals. Specifically, color carbon fiber with GO one-dimensional photonic crystal coating (colored-CF) is realized for the first time by uniformly surface depositing with vacuum filtration method. We further investigated the colored-CF's intelligent color response and associated coloring mechanism, as well as its microstructure, tensile mechanical properties. The results show that GO coating can repair the surface defects of carbon fiber and improve its specific tensile strength and modulus. Moreover, we found that the colored-CF has interesting characteristics of color response under different solvents, temperature and stress. Our approach gives inspiration for a future design of intelligent responsive carbon fiber composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]