Carbon Nanohybrid Research Articles

Synthesis of different types of carbon nanohybrid and their effects in polymer composites

Different types of carbon nanohybrid, including carbon nanotubes–graphene (CNT–G), carbon nanospheres–graphene (CNS–G), and carbon nanotubes–carbon nanospheres (CNT–CNS), were synthesized in a one-step fabrication process by chemical vapor deposition with acetylene as carbon source at different reaction temperatures and bimetallic catalyst (Ni/Cu) molar ratios, then applied as reinforcing nanofillers in polypropylene matrix to evaluate their effects on the resulting polymer composites. Characterization of the produced nanohybrids, including their size, structure, morphology, graphitization, composition, and surface area, was performed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, electron-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller (BET) surface area measurements, respectively. The influence of the different nanofillers on the nanocomposites was analyzed by Raman spectroscopy, thermogravimetric analysis, and tensile testing. Finally, a mathematical model for the mechanical properties of the nanohybrids was applied, showing good agreement with experimental results.

Two-photon excitation triggers combined chemo-photothermal therapy via doped carbon nanohybrid dots for effective breast cancer treatment

Remotely triggered drug delivery using nanoparticles is an area of great interest for targeted therapy to fight cancer. In this work, we synthesized photoresponsive nanoparticles to remotely initiate the delivery of doxorubicin (DOX) to 3D cultured human breast cancer cells (MCF-7) via NIR two-photon excitation (TPE) using nitrogen-doped and surface passivated (PEG200) carbon nanohybrid dots (CNDs). On-demand drug delivery relies on bio-compatible, photo-responsive nano-carriers with high quantum yields. A facile (5min synthesis) one-pot hot plate method was used to synthesize functionalized and surface passivated carbon nanohybrid dots (CND-P) having 53% quantum yield (QY). Compared to CNDs prepared from citric acid (CND-C) and citric acid plus urea (CND-N), CND-P had QY enhanced by factors of 12.6 and 4.4, respectively. The up-converted emission intensity of CND-P was strengthened by a factor of 4.5 over that of CND-N from nitrogen doped CNDs for similar test conditions (wavelength, excitation power and concentration). The drug loading capacity of CND-P was measured to be 0.98w/w with the ability to release DOX via two-photon excitation (TPE). Intense green luminescence was observed under both 360 and 780nm lasers using single and two-photon excitations. The highly biocompatible CND-P showed 88% cell viability at concentrations as high as 1100µg/mL. The combined chemo- and photothermal therapeutic effect of the DOX-loaded CND-P (CND-P@DOX) complex resulted in the death of 78% of the MCF-7 cells compared to 59% with DOX alone.

Tunable water sensitive polymeric composites with synergistic graphene and carbon nanotubes

Hybrid nano-carbons of the reduced graphene oxide (rGO) and carbon nanotubes (CNTs) were utilized to fabricate the electrically conductive polymeric composites which exhibited superior flexibility, conductivity and tunable sensitivity to water exposure. Besides the conduction, morphologies and microstructure of the nanocarbon networks, the static and dynamic wetting behaviors as well as the absorption properties of the hybrid nanocarbons and the polymer composites were investigated. The emphasis was put on the influence of the composition on the sensory properties. The synergistic rGO-CNTs were found to magnify the water sensing, which may attribute to the swelling effect on the CNTs entanglement segregated by the rGO sheets. The findings may greatly benefit the exploration of nanocarbons in the field of the flexible sensory materials.

Rational design of graphene @ nitrogen and phosphorous dual-doped porous carbon sandwich-type layer for advanced lithium–sulfur batteries

Lithium sulfur (Li–S) batteries show great prospect as a next generation high energy density rechargeable battery systems. However, the practical utilization of Li–S batteries is still obstructed by the shuttle effects which inducing the fast capacity fading and the loss of active sulfur. Herein, a special graphene @ nitrogen and phosphorous dual-doped porous carbon (N–P–PC/G) is presented to modify a commercial separator for an advanced Li–S battery. The N–P–PC/G nanosheet employs graphene layer as an excellent conductive framework covered with uniform layers of N, P dual-doped porous carbon on both sides which possessing massive interconnected meso-/micropores. It is demonstrated that the N–P–PC/G-modified separator can suppress the shuttle effects by coupling interactions including physical absorption, chemical adsorption and interfacial interaction. With the aid of the N–P–PC/G-modified separator, the pure sulfur cathode with high-sulfur loading of 3 mg cm−2 offers a high initial discharge capacity of 1207 mA h g−1 at 0.5 C (1 C = 1675 mA h g−1), and a maintained capacity of 635 mA h g−1 (fading rate of only 0.095% per cycle), after 500 cycles. This work suggests that combining hybrid nanocarbon with multi-heteroatom doping to modify the commercial separator is an effective approach to obtain high electrochemical performance Li–S batteries.

Carbon nanotube based hybrid nanocarbon foam

Carbon nanotube (CNT) based nanocarbon foams (NFs) and the hybrid nanocarbon foams (HNFs) are fabricated in this work. The NFs are formed by using poly(methyl methacrylate) microspheres as a template to create micro-scaled pores. The cell walls are made of CNT networks with nano-scaled pores. The interconnections among CNTs are secured using graphene and nanographite generated via carbonization of polyacrylonitrile. The resulting NFs are ultra-lightweight, highly elastic, electrically and thermally conductive, and robust in structure. The HNFs are made by infiltrating thermoplastic polymer into the NFs in a controllable procedure. Compared to NFs, the HNFs have much higher strength, same electrical conductivity, and limited increase in density. The compressive strength of the HNF increased more than 50 times while the density was changed less than 10 times due to the polymer infiltration. It is found that the deformed HNFs can recover in both structure and property when they are heated over the glass transition temperature of the infiltrated polymer. Such remarkable healing capability could broaden the applications of the HNFs.

High-performance Mn3O4/onion-like carbon (OLC) nanohybrid pseudocapacitor: Unravelling the intrinsic properties of OLC against other carbon supports

The electrochemical performance of the tetragonal hausmannite Mn3O4, when embedded on various carbon materials, onion-like carbon (OLC), carbon nanotubes (CNT), reduced graphene oxide (RGO) and activated carbon (AC) (i.e., OLC/Mn3O4, CNT/Mn3O4, GO/Mn3O4, and AC/Mn3O4), has been investigated as electrode material for symmetric and asymmetric pseudocapacitor device. The nanohybrid electrode materials demonstrated higher electrochemical performance (in terms of specific capacitance and rate capability as energy storage devices) compared to the pure Mn3O4. The OLC/Mn3O4-based symmetric pseudocapacitor device exhibited higher specific capacitance of 195 F g−1, specific energy of 4.3 Wh kg−1 and power density of 52 kW kg−1 compared to other carbon nanohybrid materials studied. From the symmetric experiments, the best-performing OLC/Mn3O4 nanohybrid has been further explored as high-voltage asymmetric pseudocapacitor, with maximum energy and power densities of ca. 19 Wh kg−1 (at 0.1 A g−1) and 45 kW kg−1 (at 10 A g−1) respectively. The high-performance of the OLC-based system compared to the other carbon systems is ascribed to the combined unique intrinsic properties of the OLC; high electrical conductivity, highly accessible outer surface and large interparticle pore volumes. The above properties have ensured OLC/Mn3O4 nanohybrid as a suitable candidate for the high-voltage asymmetric pseudocapacitor device.

Sulfonated poly(ether ether ketone) [SPEEK] nanocomposites based on hybrid nanocarbons for the detection and discrimination of some lung cancer VOC biomarkers.

The analysis of a volatolome is a promising approach to allow the early diagnosis of diseases such as cancers. However, one important challenge is to take the chemical fingerprint of the complex blend of volatiles, for many of them only present at the sub-ppm level. We have investigated a facile route to differentiate the chemo-resistive behaviour of quantum resistive vapour sensors (vQRS) and provide them with a strong methanol selectivity by simply changing the sulfonation degree of poly(ether ether ketone) up to 85%. The hybridization of carbon nanotubes (CNTs) with fullerene (C60) structured in a 3D architecture by spray layer-by-layer (sLbL) has allowed us to boost significantly the sensitivity of sensors to reach the sub-ppm level (340 ppb). After their integration into an e-nose, PEEK-nanocarbon sensors were found to effectively discriminate both single and binary mixtures of volatile organic compounds (VOCs) and among all biomarkers to detect preferentially methanol with a high signal to noise ratio (200).

Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique

Carbon nanohybrid material (CNF/γ-Fe2O3) was obtained via a modified sol-gel technique consisting of two steps: functionalization of carbon nanofibers (CNF) in H2SO4/HNO3 followed by synthesis using Fe(NO3)3∙9H2O. As a result, the iron content of the CNF/γ-Fe2O3 was increased by more than twice from about 40% to about 87% mass percent, compared to the pristine CNF and oxidized CNF specimens, as proved by energy dispersive X-ray fluorescence. Scanning electron microscopy images exhibited “cumulus” on the CNF/γ-Fe2O3 specimen surface, which showed the highest iron mass percentage, proved by energy dispersive X-ray spectroscopy. Transmission electron microscopy images confirmed attachment of γ-Fe2O3 cumulus to the inner and outer surfaces of the CNF walls after synthesis. The characteristic peaks of Fe 2p3/2 and Fe 2p1/2 appeared in the XPS spectra obtained on CNF/γ-Fe2O3. In addition, X-ray diffraction (XRD) results indicated formation of γ-Fe2O3 during the synthesis process. The Raman spectrum of the CNF/γ-Fe2O3 sample displays peaks with positions close to characteristic peaks of highly crystalline and monodisperse maghemite nanocrystallites. The synthesis of CNF/γ-Fe2O3 leads to an increase in the hydrophilicity of CNF and magnetic properties at room temperature.

Graphene nanobuds: Synthesis and selective organic derivatisation

Herein, the formation and selective organic derivatisation of graphene nanobud, an all carbon nanohybrid comprised by C60 and graphene, are presented. C60 cages are directly attached to the graphenic surface with stable covalent bonds. Importantly, prepared graphene nanobud shows remarkable dispersibility, decreased number of defects and highly aromatic character that are associated to improved electrical conductivity compared to pristine graphene. The high chemical reactivity of the curved sp2 carbon atoms of C60 led to a selective covalent attachment of organic groups onto C60 avoiding damage of the graphene aromatic system.

Investigation of oxygen reduction and methanol oxidation reaction activity of PtAu nano-alloy on surface modified porous hybrid nanocarbon supports

We investigate the electrocatalytic activity of PtAu alloy nanoparticles supported on various chemically modified carbon morphologies towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The surface-modification of graphene nanosheets (f-G), multi-walled carbon nanotubes (f-MWNTs) and (graphene nanosheets-carbon nanotubes) hybrid support (f-G-MWNTs) were carried out by soft functionalization method using a cationic polyelectrolyte poly-(diallyldimethyl ammonium chloride). The Pt and PtAu alloy nanoparticles were dispersed over chemically modified carbon supports by sodium-borohydride assisted modified polyol reduction method. The electrochemical performance of all electrocatalysts were studied by half- and full-cell proton exchange membrane fuel cell (PEMFC) measurements and PtAu/f-G-MWNTs catalyst comparatively yielded the best catalytic performance. PEMFC full cell measurements of PtAu/f-G-MWNTs cathode electrocatalyst yield a maximum power density of 319 mW cm−2 at 60 °C without any back pressure,which is 2.1 times higher than that of cathode electrocatalyst Pt on graphene support. The high ORR and MOR activity of PtAu/f-G-MWNTs electrocatalyst is due to the alloying effect and inherent beneficial properties of porous hybrid nanocarbon support.

Self-sensing cementitious composites incorporated with botryoid hybrid nano-carbon materials for smart infrastructures

The botryoid hybrid nano-carbon materials were incorporated into cementitious materials to develop a new type of self-sensing cementitious composites, and then the mechanical, electrically conductive, and piezoresistive behaviors of the developed self-sensing cementitious composites with botryoid hybrid nano-carbon materials were comprehensively investigated. Moreover, the modification mechanisms of botryoid hybrid nano-carbon materials to cementitious materials were also explored. The experimental results show that the compressive strength and the elasticity modulus of the self-sensing cementitious composites botryoid hybrid nano-carbon materials decrease with the increase in the botryoid hybrid nano-carbon material content, while the Poisson’s ratio does the opposite. The percolation threshold zone of the self-sensing cementitious composites botryoid hybrid nano-carbon materials is from 2.28 to 3.85 vol.%. The optimal content of botryoid hybrid nano-carbon materials is 3.38 vol.% for piezoresistivity of the self-sensing cementitious composites botryoid hybrid nano-carbon materials. The amplitude of fractional change in resistivity goes up to 70.4% and 28.9%, respectively, under the monotonic compressive loading to failure and under the repeated compressive loading within elastic regime. The piezoresistive stress/strain sensitivity reaches (3.04%/MPa)/354.28 within elastic regime. The effective modification of botryoid hybrid nano-carbon materials to electrically conductive and piezoresistive properties of cementitious materials at such low content is attributed to their botryoid structures, which are beneficial for the dispersion of botryoid hybrid nano-carbon materials and the formation of conductive network in cementitious materials. The use of botryoid hybrid nano-carbon materials provides a new bottom–up design and fabrication approach for nano-engineering multifunctional cementitious composites.

Long-Life Silicon/Graphite Anode with Nano Carbon Coatings for Lithium Ion Battery - Graphene Nanowalls and Nitrogen Incorporated Ultrananocrystalline Diamond

Although lithium ion batteries (LIBs) have been used in many consumer and industrial products, the energy storage capacity per volume/weight and the battery cycling lifetime have much room for further improvement. This is especially challenging for high demanding applications such as long-range electric vehicles, and smart grid renewable energy storage. Among LIB anode materials, graphite is the most common one in the market today. Many novel anode materials have been studied in pursuit of much higher battery energy storage capacity for a given volume and weight. Among them, silicon is the most attractive one which theoretically is capable of storing more than ten times of energy than that of graphite anode for the same anode weight. However, silicon suffers from extensive volume expansion and shrinkage by about 400% when it cycles through fully charged and discharged states. The volume difference leads to breakage of silicon particles and the loss of their electrical contacts to the current collector and thus its capability of further discharging and charging. On the other hand, graphite has a layered structure, which suffers from breakage between adjacent layers into smaller pieces and thus possibly loses the capability of broken apart small graphite pieces in charging and discharging. Therefore, technologies for preventing aforementioned huddles against achieving long-life and high-capacity LIBs are highly desirable. Novel electrically conductive ultrananocrystalline diamond, graphene nanowalls, and diamond-graphene hybrid nano-carbon coatings have been applied by plasma enhanced chemical vapor deposition technique to graphite and silicon based LIB anodes and achieved much longer cycling lifetime compared to those without such nano carbon coatings. This paper will present the nano-carbon coating processes, materials characterization, LIB fabrication processes, and the characterization of LIB half cells which demonstrates enhance lifetime and charge storage capacity.

Nanocarbon Paper: Flexible, High Temperature, Planar Lighting with Large Scale Printable Nanocarbon Paper (Adv. Mater. 23/2016)

On page 4684, C. Dames, L. Hu and co-workers report highly efficient, broadband lighting from printed hybrid nanocarbon structures with carbon nanotubes and reduced graphene oxides. The fast response and excellent stability of the flexible lighting can find applications in a range of emerging applications where the shape and format, as well as being lightweight, are important.

Novel hybrid nanocarbons/poly(dimethylsiloxane) composites based chemiresistors for real time detection of hazardous aromatic hydrocarbons

Hybrid nanocarbons have been reported to have synergetic advantages in several mechanical and electrical applications. However, little is understood how two geometrically different nanocarbons can affect the response of a chemiresistive sensor. The study reports development of poly(dimethylsiloxane) (PDMS)/carbon nanotube (CNT) and nanocarbon black based novel chemiresistive sensors through a solvent free route. These PDMS based sensors demonstrated high sensitivity and reversible response against benzene, toluene, ethyl benzene and xylene (BTEX) under dynamic flow as well as under static vapour conditions. It was found that the sensing response had a strong correlation with the BTEX-PDMS interaction parameters (χ12). However, such dependence was not observed at 3 wt% loading of CNT, due to CNT induced changes in the diffusion behavior of BTEX. CNT loading affected detection of each analyte differently; though, the principle component analysis using an array of four chemiresistors with different CNT content demonstrated distinct pattern only for benzene. Intriguingly, the sensitivity and the temperature coefficient of resistance of chemiresistors decreased; whereas, the detection range increased considerably with addition of CNT.

Wet Chemistry Synthesis of Multidimensional Nanocarbon-Sulfur Hybrid Materials with Ultrahigh Sulfur Loading for Lithium-Sulfur Batteries.

An optimized nanocarbon-sulfur cathode material with ultrahigh sulfur loading of up to 90 wt % is realized in the form of sulfur nanolayer-coated three-dimensional (3D) conducting network. This 3D nanocarbon-sulfur network combines three different nanocarbons, as follows: zero-dimensional carbon nanoparticle, one-dimensional carbon nanotube, and two-dimensional graphene. This 3D nanocarbon-sulfur network is synthesized by using a method based on soluble chemistry of elemental sulfur and three types of nanocarbons in well-chosen solvents. The resultant sulfur-carbon material shows a high specific capacity of 1115 mA h g(-1) at 0.02C and good rate performance of 551 mA h g(-1) at 1C based on the mass of sulfur-carbon composite. Good battery performance can be attributed to the homogeneous compositing of sulfur with the 3D hierarchical hybrid nanocarbon networks at nanometer scale, which provides efficient multidimensional transport pathways for electrons and ions. Wet chemical method developed here provides an easy and cost-effective way to prepare sulfur-carbon cathode materials with high sulfur loading for application in high-energy Li-S batteries.

Electrochemical assessment of local cytosine methylation in genomic DNA on a nanocarbon film electrode fabricated by unbalanced magnetron sputtering

This paper reports the first electrochemical assessment of the cytosine methylation status in genomic DNA by using a combined bisulfite restriction analysis on a nanocarbon film electrode. The film electrode consists of sp2 and sp3 hybrid nanocarbon, which is fabricated with unbalanced magnetron sputtering equipment and is suitable for cadmium ion determination. The electrochemical assessment was performed by measuring the oxidation current with an anodic stripping voltammogram derived from the labeled cadmium-containing nanoparticles, following digestion by a restriction enzyme (HpyCH4IV). We succeeded in estimating the methylation ratio at a specific CpG site from genomic DNA in a diluted PCR product solution from 0.5 to 10nM.

Effect of the sp(2)/sp(3) Ratio in a Hybrid Nanocarbon Thin Film Electrode for Anodic Stripping Voltammetry Fabricated by Unbalanced Magnetron Sputtering Equipment.

The effect of the sp(2)/sp(3) ratio in an unbalanced magnetron sputtered nanocarbon film electrode was studied for determining Cd(2+) and Pb(2+) by anodic stripping voltammetry (ASV). The signal-to-noise ratio in the ASV measurement improved as the sp(3) concentration in the carbon film increased because the noise current decreased with the increasing sp(3) concentration. The detection limits with a carbon film containing 50% sp(3) were 0.25 and 1.0 μg L(-1) for Cd(2+) and Pb(2+) with high repeatability (Cd: 4.6% and Pb: 6.4%, n = 3). For a real sample measurement, a pretreatment system combining a photooxidation reactor and a cation exchange column was used to eliminate the interference from EDTA and Cu(2+), which forms a stable complex or alloy with Cd(2+) and Pb(2+). More than 99% of the interference was eliminated, and accurate signal currents for Cd(2+) and Pb(2+) were successfully obtained with the pretreatment system.

SnO2/corncob-derived activated carbon nanohybrid as an anode material for lithium-ion batteries

A facile synthesis of SnO2/corncob-derived activated carbon (CAC) composite was proposed, and the CAC used here has high specific surface area (over 3000 m2/g) and ample oxygen-containing functional groups. The microstructures and morphology as well as electrochemical performance of the SnO2/CAC composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and relevant electrochemical characterization. The results show that the mass ratios of SnO2 to CAC have a significant effect on the structures and properties of the composites. The sample with 34% SnO2 delivered a capacity of 879.8 mAh/g in the first reversible cycle and maintained at 634.0 mAh/g (72.1% retention of the initial reversible capacity) after 100 cycles at a current density of 200 mA/g. After 60 cycles at different specific currents from 200 to 2000 mA/g, the reversible specific capacity was still maintained at 632.8 mAh/g at a current density of 200 mA/g. These results indicate that SnO2/CAC can be a desirable alternative anode material for lithium ion batteries.

Preparation, electromagnetic and enhanced microwave absorption properties of Fe nanoparticles encapsulated in carbon nanotubes

Abstract Using hollow Fe2O3 particles as the catalyst, the core/shell structured Fe/carbon nanotube (CNT) hybrid could be synthesized by a chemical vapor deposition method without the hydrogen reduction process. Based on the obtained results, a possible growth mechanism of the Fe/CNT hybrid was discussed. And the investigations of electromagnetic and microwave absorption performances indicate that a minimum reflection loss (RL) value of the obtained sample is ca. −40.15 dB at 17.15 GHz with a matching thickness of 1.5 mm, and the RL value below −20 dB can be obtained in the whole frequency range (1.0–18 GHz) with the sample thickness varies from 1.3 to 10.0 mm. The results demonstrate that a simple and environment-friendly route has been proposed for the production of core/shell structured carbon nanohybrid. The obtained Fe/CNT hybrid exhibits excellent microwave absorption properties and has potential applications in thin thickness and light-weight microwave absorbers.

In-situ Grown Hybrid Nanocarbon Composite for Dye Sensitized Solar Cells

Herein, a facile in-situ grown nanocarbon composite including one dimensional (1D) carbon nanotubes (CNTs) and two dimensional (2D) graphene nanosheets on FTO conductive glass substrates is used directly as a transparent counter electrode (CE) for dye sensitized solar cells (DSSCs) without any post-treatments. In the novel nano-composite, the CNTs without aggregations are not woven into each other, which is beneficial for the transport of carriers. Additionally, the 2D graphene between CNTs and the FTO conductive glass substrates is thought as the platform for accelerating the ballistic transport. It is found that the hybrid CNTs/graphene nano-composite exhibits relative high electrocatalytic activity for the reduction of triiodide. Besides, the design of bifacial DSSC with the hybrid transparent CNTs/graphene CE improves the utilization ratio of incident light. As a consequence, the bifacial DSSC with the optimized hybrid CNTs/graphene exhibits energy conversion efficiency (η) of 5.16% and 4.30%, corresponding to front- and rear-side illumination, respectively.