Graphene Tubes Research Articles

Impact Loading on Polymer Nanocomposites - A Comprehensive Review

In recent days, the application of polymer nanocomposites (NC) has grown exponentially due to its varied applications and efficacy. However, it is also associated with various challenges and need of optimal solutions to address the same. Excellent properties in the area of high strain rate applications are usually addressed during fabrication of nanocomposites using graphene, nano fillers, nano clay and carbon nano tubes. Such NC offer good properties associated with thermal stability and unique desirable properties making them excellent replacements for conventional materials used so far. Their applications are found in defense, space and automobile sectors. Though NC have numerous positive characteristics, the reason behind their failure mechanism under loading conditions with static and dynamic is unanswered or not comprehensively clear. This article enumerates the collective review of the challenges and solutions addressed by various researchers. It includes techniques used for characterizing nanocomposites with respect to failure governing mechanism for both organic and inorganic NC.

Self-Assembled Synthesis of Graphene Tubes from Melamine Catalyzed by Calcium Carbonate

This study investigates the carbon products generated by melamine under various heat-treatment temperatures with the catalysis of calcium carbonate. We discovered that the cost-effective precursor melamine readily self-assembles and curls into graphene tubes when catalyzed by the alkaline earth salt CaCO3 at elevated temperatures. Under heat-treatment conditions of 1100 °C and 1200 °C, the growth morphology of graphene tubes with open structures and exceptionally large diameters was observed, and the diameters reached the micron level. These products exhibit a high degree of carbonization and an extremely low nitrogen content, as low as 1.7%. Further, the intensity ratio (ID/IG) of the D band and the G band is as low as 0.79 in Raman characterization. The results show that the products have a certain graphite structure, which proves the catalytic activity of CaCO3. This is attributed to the incorporation of CaCO3 into the raw material system, which impedes the complete thermal decomposition of melamine. On the other hand, the resulting CaO particles are evenly distributed along the tubular products, providing certain support for their self-assembly and growth, thereby achieving the efficient growth of graphene tubes.

Multiple strategies regulating the d-band center of Ni2P/NiFe2O4 @N-GTs hierarchical nanoarchitecture as efficient electrocatalyst for overall water splitting

The rational design of highly active electrocatalysts for water electrolysis remains challenging for green hydrogen utilization. Herein, guided by the correlation between the electroactivity and the d-band center (Ed), a novel hierarchical nanoarchitecture (Ni2P/NiFe2O4-VO@N-GTs) was fabricated, in which, Ni2P nanoparticles are grown on the oxygen vacancy-rich NiFe2O4 nanosheet arrays anchoring on N-doping graphene tubes. The results reveal that the multiple strategies including the vacancies and heterogeneous interface construction effectively induce the charge redistribution, and further adjust the Ed to the appropriate energy level, which endows the optimal balance between the adsorption and desorption ability of the catalyst to reaction intermediates, thus leading to the conspicuous electrocatalytic activity. Additionally, the hierarchical nanoarchitecture contributes to the exposure of more active sites, the efficiency of electron transfer, and the release of generated gas. Hence, Ni2P/NiFe2O4-VO@N-GTs presents superior bifunctional activity, especially a low overpotential of 194 mV at 10 mA cm−2 for OER. The corresponding overall water electrolyzer owns a lower cell voltage and long-term durability with continuously operating over 330 h at 100 mA cm−2, outperforming the most reported bifunctional electrocatalysts. This work presents an effective pathway for regulating the Ed through multiple strategies to improve the catalytic performance of catalysts.

Ru-doping W4.6N4 nanoparticles anchored on N-doped graphene tubes as efficient hydrogen evolution electrocatalyst

Designing efficient electrocatalysts for hydrogen evolution reaction (HER) is essential to facilitate hydrogen energy applications. Herein, efficient strategies of doping with metal atoms (Ru) and incorporating with conductive carbon-based material (N-doping graphene tubes) have been developed to construct the hybrid electrocatalyst RuW4.6N4@N-GTs, in which, Ru-doped W4.6N4 nanoparticles integrated on the surface of N-doped graphene tubes. RuW4.6N4@N-GTs reveals superior HER activity and good stability, with a low overpotential of 29 mV to deliver the current density of 10 mA cm−2 and a low Tafel slope of 57 mV dec−1. The unique 3D nano-structure morphology of abundant homogeneous RuW4.6N4 nanoparticles supported on conductive N-GTs network carrier contributes to expose more electrochemical active sites, promoting electrolyte transport and gas emission. At the same time, the N-GTs skeleton could prevent the RuW4.6N4 particles from agglomerating and collapsing, thus leading to the superior stability during HER process. The in situ Ru heteroatom doping could cause the directional electron transfer and more nitrogen vacancies, thus modulating the electron structure of catalysts and optimizing the hydrogen adsorption free energy. The synergistic effect of the above merits endows RuW4.6N4@N-GTs with outstanding HER performance for potential applications in the hydrogen production field.

Electrochemical activity of self-supporting nitrogen-doped graphene for the degradation and in-situ determination of methylene blue

Environmentally friendly wastewater treatment and online pollution monitoring systems, important for water quality control, are yet to be developed. Electrochemical strategies combining the electrocatalytic degradation and electroanalysis of organic pollutants are expected to achieve this key technology. This study employed a chemical vapor deposition method using N₂ gas as the nitrogen source and applying an alternating electric field to prepare self-supporting nitrogen-doped graphene (NG) tubes with a wall thickness of up to 480 μm comprising few-layer NG nanosheets. The correlation between the properties of these materials and the electrocatalytic activity for methylene blue (MB) was investigated. The feasibility of the electrochemical strategy for online wastewater treatment and detection was validated using a combination of UV–visible spectroscopy and differential pulse voltammetry. The NG tube with the N-C bond distribution regulated by adjusting the methane flow rate and growth time exhibited high electrocatalytic activity, rapidly degrading 50 mg L⁻¹ of MB within 36 min and tracking changes in MB concentration. The NG tubes were assembled in an electrocatalytic meter pen for water treatment, achieving a degradation efficiency of 99.4 % and a detection limit of 0.3 mg L−1 for the MB solution, quite satisfactory for emerging simultaneous degradation and monitoring processes. The developed self-supporting NG tubes are promising materials for electrocatalytic degradation anodes and sensing electrodes in water treatment. Dual-functional electrocatalytic systems have potential applications in water quality monitoring and improvement.

Cross-flow separation characteristics and piloting of graphene oxide nanofiltration membrane sheets and tubes for kraft black liquor concentration

Dewatering of weak black liquor (WBL) in the kraft cycle by evaporation is highly energy intensive. Membranes are an attractive alternative for energy-efficient dewatering, but existing commercial polymeric or ceramic membranes are either degraded in BL or have high capital costs. Our recent works have demonstrated the engineering of graphene oxide (GO) nanofiltration membranes, their stability and promising performance in BL conditions, and preliminary scale-up into sheets and tubes. Here, we describe in detail the separation characteristics of GO membrane sheets and tubes under real BL conditions and crossflow operation. Recycle-mode piloting of a GO tubular membrane showed average “production flux” of 16 L/m2/h (LMH) and high rejections of lignin (98.3%), total solids (66%), and total organic carbon (83%), with no signs of irreversible fouling identified. A corresponding GO sheet membrane produced an average flux of ~25 LMH and maintained high lignin rejection of ~97% during a slipstream pilot at a kraft mill site using WBL with ~16 wt% total solids (TS). Finally, we piloted a Dow/DuPont XUS1808 polyamide composite reverse osmosis (RO) membrane for last-mile processing of the GO nanofiltration membrane permeate. The RO membrane showed a steady state flux of 19 LMH at 65 bar and produced ~0.02 wt% TS water product, which is highly suitable for reuse in pulp washing operations in the kraft process. The results have strong positive implications for the industrial application of GO membranes in BL concentration and other related applications.

Hybrid MOFs Supercapacitor: A Mini Review

In the world of energy storage devices, Supercapacitors occupy a very unique and pivotal position. Their rapid rate of discharge gives them high power density. They have high reversibility and are robust to a large number of charging and discharging cycles. Sustained research has revealed a certain set of properties and behaviour, that every prospective candidate supercapacitor material must possess. Metal organic frameworks (MOFs) with unique textural properties, excellent specific surface area, tuneable porous structure and distinctively advantageous electrochemical behaviour are prominent candidates for the use in energy storage applications. However pristine MOF based materials are handicapped due to their low conductivity and poor mechanical stability. These inherent deficiencies can be overcome by hybridizing pristine MOFs with other materials like carbon materials (Activated Carbon, Graphene and Carbon Nano Tubes), conducting polymers, metals, and small molecules through variety of methods. This review puts the spotlight on the utilization, growth and various forms of hybrid materials based on MOFs for supercapacitor applications. It also highlights the various surface engineering techniques on the materials for high potential applications.

A nitrogen-doped graphene tube composite based on immobilized metal affinity chromatography for the capture of phosphopeptides

A novel immobilized metal affinity chromatography (IMAC) functional composite, mNi@N-GrT@PDA@Ti4+, was fabricated based on ultrathin magnetic nitrogen-doped graphene tube (mNi@N-GrT) after chelated Ti4+ with polydopamine, following as a magnetic solid-phase extraction sorbent for rapidly selective enrichment and mass spectrometry identification of phosphorylated peptides. After optimized, the composite exhibited high specificity in the enrichment of phosphopeptides from the digest mixture of β-casein and bovine serum albumin (BSA). The robust method presented the low detection limits (1 fmol, 200 μL) and excellent selectivity (1:100) in the molar ration mixture of β-casein and BSA digests. Furthermore, the selective enrichment of phosphopeptides in the complex bio-samples, was successfully carried out. The results showed that 28 phosphopeptides were finally detected in mouse brain, and 2087 phosphorylated peptides were identified in the HeLa cells extracts with specific selectivity of 95.6%. The enrichment performance of mNi@N-GrT@PDA@Ti4+ was satisfactory, suggesting that the functional composite provided a potential application in the enrichment of trace phosphorylated peptides from the complex biological matrix.

Chromium doping and in-grown heterointerface construction for modifying Ni3FeN toward bifunctional electrocatalyst toward alkaline water splitting

Exploring high-performance non-noble metal electrocatalysts is pivotal for eco-friendly hydrogen energy applications. Herein, featuring simultaneous Chromium doping and in-grown heterointerface engineering, the Cr doping Ni3FeN/Ni heterostructure supported on N-doped graphene tubes (denoted as Cr–Ni3FeN/Ni@N-GTs) was successfully constructed, which exhibits the superior bifunctional electrocatalytic performances (88 mV and 262 mV at 10 mA cm−2 for HER and OER, respectively). Furthermore, an alkaline electrolyzer, employing Ni3FeN/Ni@N-GTs as both the cathode and the anode, requires a low cell voltage of 1.57 V at 10 mA⋅cm−2. Cr doping not only modulates the electronic structure of host Ni and Fe but also synchronously induces nitrogen vacancies, leading to a higher number of active sites; the in-grown heterointerface Cr–Ni3FeN/Ni induces the charge redistribution by spontaneous electron transfer across the heterointerface, enhancing the intrinsic catalytic activity; the N-GTs skeleton with excellent electrical conductivity improves the electron transport and mass transfer. The synergy of the above merits endows the designed Cr–Ni3FeN/Ni@ N-GTs with outstanding electrocatalytic properties for alkaline overall water splitting.

Template free preparation of graphene tubes from polyimide catalyzed by calcium carbonate.

This work reports a new means of preparing graphene tubes (GTs) without relying on chemical vapor deposition (CVD) and it's template-free. Surprisingly, we found that under the action of calcium oxide (CaO) and after 1500 °C heat treatment, a large amount of GTs grew on the surface of polyimide (PI). These nanotubes have a maximum diameter of about 600 nm and a length of up to millimeters, and some nanotubes even have a branching structure. We propose a simple, effective and green method which exhibits prospects for large-scale production of GTs using polymeric materials.

Piezo-resistive Properties of Polymer based cement nano composites

The nano technology has potential applications in development self-sensing smart materials. These nano materials is used in cement matrix or polymer base to improve the mechanical and piezo electrical properties of composites. In the present study, the graphene and carbon nano tube are added in matric, which acts as the conductive fibre into polymer cement composites. Cement based polymer composites are prepared by adding carbon fibre, epoxy resin, carbon nano tube and graphene as conductive filler in matrix to prepare the distinctive specimens for experimental investigations. The electro mechanical test are carried out to assess the piezo electrical properties of these composites subjected gradual increase of mechanical loading such as flexural and compression. The present study describes the self-sensing piezo-resistive capability of composite to monitor the strain in structures. The experimental test elucidates the addition of epoxy in cement matrix enhance the mechanical properties while carbon nano tube and graphene proves to be promising smart self-sensing materials in composites by measuring the variation in stress at critical regions. The SEM with EDX analysis shows that epoxy resin act as binding agent which hinder the cracks propagations and improves the mechanical properties of composites.

Effect of nano graphene and CNT addition on coating properties in friction surfacing process

Abstract In this study, the wear behaviour of the composite material obtained as a result of the coating process by adding nano-size powder to the consumable rod with the friction surfacing method was investigated. An amount of 3–5 wt% nano graphene and carbon nano tube (CNT) were added into the hole drilled at a certain depth in the center of the consumable rod, and then the rod was subjected to sintering process. The obtained consumable rod was deposited on the substrate material at a certain rotational speed, horizontal and vertical progression speeds by friction surfacing method. Wear tests were carried out by subjecting the deposited surface samples to the pin-on-disc wear test. According to the results obtained, the increase in the additive ratio decreased the wear rate by approximately 30% in the 3 wt% graphene additive sample and 75% in the 5 wt% additive sample for 900 m wear distance. The same CNT additive ratios decreased the wear rate in the sample by 41% and 58%, respectively.

Preparation of Spiral Nitrogen-Doped Macroscopic Graphene Tube and Tuning the Activity of Oxygen Catalysis by Twisted Ferrum (Fe) Wires

A FeNx-C-based catalyst is considered one of the most promising candidates for the highest oxygen reduction reaction (ORR) activities among nonprecious metal-based electrocatalysts. In this work, a unique catalyst of nitrogen-doped twisted macroscopic graphene tubes decorated with Fe-Nx and bamboo-like carbon nanotubes (CNT) was prepared by using twisted iron wire as a template and cyanamide as a carbon source. The microstructure and physicochemical natures of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopic (XPS), X-ray diffraction (XRD), and nitrogen adsorption/desorption measurements. Torsion can promote the dislocation of the iron wire lattice, and activate the surface Fe atoms, thus leading to the growth of bamboo-like carbon nanotubes and forming iron nitride. The product has a graphene-like macroscopic tube structure and exhibits excellent ORR activity. Such excellent ORR performance may be ascribed to the synergistic effect, including high ORR catalytic sites caused by the dislocation of the iron wire lattice, nitrogen heteroatoms doping, favorable reactant transport channels provided by macroscopic tube structure, and fast electron transfer rate induced by 3D continuous networks.

Preparation of super thin and defect rich graphene shell and its application for high performance supercapacitor electrode and novel ORR catalyst support

We report for the first time that zinc oxide (ZnO) can not only effectively catalyze the conversion of acetylene into graphene, but also greatly lower the growth temperature to only 400 °C. With this method, super thin and defect rich graphene shell (TD-GS) is successfully prepared for the first time using ZnO nanoparticles as both the catalyst and template. The growth of TD-GS is tracked and monitored and its growth mechanism is illustrated. The as-prepared TD-GS exhibits remarkable performance as electrode material for applications in supercapacitors or novel catalyst support for oxygen reduction reaction. We also demonstrate that by simply adjusting the growth conditions or process, new carbon structures, like opened TD-GS, TD-GS aerogel and even graphene tube can be facilely realized.

Fabrication of graphene, graphite and multi wall carbon nano tube based thin films and their potential application as strain sensor

Carbon based nanomaterials are extensively used in the manufacturing of flexible electronic devices due to their numerous favorable properties. Such devices have shown remarkable sensitivity with excellent stability when implemented in various flexible environments. But the formulation of conductive inks using carbon based nanomaterials presented some challenges in the optimization of various ink parameters like rheology, surface tension, particle size etc. In this paper, we present graphite, graphene and multi-wall carbon nano tube (MWCNT) based flexible resistive strain sensors on polymer substrate using a simple and solvent free fabrication process. A controllable conductive thin film is obtained and designed into two different patterns viz. ‘Straight Line’ (line) and ‘Serpentine’ (serp) to enhance the sensing performance of the film. The electrical performance has been evaluated in terms of current-voltage characteristics. The result indicates the resistive behavior of all the devices under investigation. The bending measurements have been conducted; the resistive strain sensor exhibits significant resistance variation during bending applications. There has been a significant change in the electrical resistance of each sample for different strain level i.e. ∼ 20% for MWCNT(line) and MWCNT (serp), ∼30% for Graphite(line) and Graphene (line) and ∼50% to 60% for Graphite (serp) and Graphene (serp). High sensitivity of the ‘Serpentine’ patterns in comparison to ‘Straight Line’ patterns indicates the importance of various patterns in the manufacturing of flexible sensors. Surface morphology and structural information of the fabricated devices have also been analyzed and investigated.

High Zinc Utilization Aqueous Zinc Ion Batteries Enabled by 3D Printed Graphene Arrays

The commercialization of aqueous zinc ion batteries requires good reversibility and high zinc utilization of zinc anode. For commonly applied 2D zinc anodes (zinc foils), their electrochemical performance and reversibility are often negatively correlated with the zinc utilization owing to the formation of zinc dendrites at the electrode-separator interphase. To overcome the disadvantages of 2D geometric design of zinc anode, this work fabricated two types of 3D printing graphene arrays (3DGs), tube arrays and pilar arrays, to simultaneously improve the reversibility and utilization of zinc anodes. The highly ordered 3D printed tubes/pillars array structures can accommodate the significant volume change during the zinc reversibly deposition/dissolution process and modify the zinc deposition on 3DGs. The array structures can also buffer the interaction between the metallic zinc and separator to protect AZIBs from short circuits. Consequently, the 3DGs showed considerable columbic efficiencies at current densities of 10–80 mA cm−2. The 3DGs@Zn anode delivered a lifespan of 1100 h in zinc symmetric cell at 2 mA cm−2 (1 mAh cm−2). The pouch cells fabricated with 3DGs@Zn anodes and V2O5 cathode delivered areal capacity (3.76 mAh cm−2) and zinc utilization (47.12%) under a practical N/P ratio (1.74:1). This work will overcome the limitations of the 2D geometric design of anodes for next-generation battery technologies.

Cobalt-based N-doped bamboo-like graphene tubes with enhanced durability for efficient oxygen reduction reaction in direct borohydride fuel cell

Exploring efficient non-precious metal cathode catalysts is attracting ever-increasing interest in the development of direct borohydride fuel cell (DBFC). Herein, a cobalt-based nitrogen-doped bamboo-like graphene tube (Co-NGT) is prepared as an efficient cathode catalyst. The Co-NGT consists of bamboo-like graphene tubes (40–130 nm in diameter and ∼10 μm in length), as well as cobalt nanoparticles (50–100 nm in diameter) confined in the graphene tubes. The Co-NGT shows an onset reduction potential of 0.964 V and an almost four-electron pathway towards oxygen reduction reaction, as well as a negative shift of 8 mV in half-wave potential after 10,000 CV cycles. The Tafel slope of the Co-NGT catalyst is 47 mV decade−1, which is by ca. 37.8 mV decade−1 smaller than for Pt/C. A DBFC using the Co-NGT cathode yields the biggest power density of 453 mW cm−2 at 60 °C and a life span of over 120 h. The excellent electrocatalytic properties and superior durability of Co-NGT catalyst arise from the highly graphitized NGT, providing strong interaction with Co nanoparticles and mitigating the agglomeration of Co nanoparticles. Our study guides for composition and structural design of high-efficient cathode catalysts of DBFC.

To Investigate Mechanical Properties of Al-based Composite Reinforced with Waste Product

The most common use for aluminium metal matrix composite, or AMMC, is variety of industrial submissions, including those in aerospace, automotive, marine, and sports industries, amongst many others. The most important reinforcing components for manufacturing AMMC are SiC, aluminium oxides, MnO, graphene, and carbon nano tubes, since these components are often used in practice. This article’s goal is to build AMMCs that are reinforced with Silicon carbide (SiC) and Alumina (Al2O3). In order to make AMMC, a procedure known as stir casting is used. Since the last several years, increased attention has been placed on the preparation of AMMCs employing agro waste as reinforcing materials. Examples of such waste are rice husk and/or SiC. As soon as the Al-matrix material has been melted using this method and churned violently, reinforcing material is added to one side of this vortex, creating a spherical structure. The AMMCs may be prepared via a procedure called stir casting, which involves a violent and whirling motion. In the beginning, the furnace is used to melt the aluminium alloy (AA3105) when the metal is in a semisolid state. The reinforcing materials, also known as SiC and Alumina (Al2O3), are warmed to temperatures of 260 and 220 degrees Celsius, respectively. According to the findings of AMMC, tensile strength and hardness of material both rose by 22.41 percent and 45.5 percent, respectively, when they were reinforced with 4.75 weight percent of each kind of reinforcement (SiC, Al2O3, and 1 percent Cr). When 1 percent Cr, 4.75 weight percent SiC, and 4.75 weight percent Al2O3 of composite material are used.

Doping and heterojunction strategies for constructing V-doped Ni3FeN/Ni anchored on N-doped graphene tubes as an efficient overall water splitting electrocatalyst

Benefiting from the synergy of doping and heterojunction strategies, V-Ni3FeN/Ni@N-GTs electrocatalyst composed of heterojunction V-Ni3FeN/Ni anchored on N-doped graphene nanotubes exhibits superior catalytic activity for overall water splitting.

High Performance Sodium Ion Anodes Based on Sn4P3 Encapsulated within Amphiphilic Graphene Tubes

AbstractHigh‐performance sodium‐ion anode composites are synthesized through confined growth Sn4P3 nanoparticles within amphiphilic graphene tubes, which provide mechanical robustness, the ability to confine Sn4P3 particles with their highly conductive frameworks, and the capability to accommodate the volume change of the particles during cycling. This unique structure endows a sodium‐ion anode with high reversible capacity (821 mA h g−1), excellent rate capability (326 mA h g−1 at 20 A g−1), and cycling stability (>90% reversible capacity retention after 500 cycles). This strategy can be extended to other conversion‐ and alloying‐type materials that experience dramatic volume change during charging and discharging.