Surface Modification Of Carbon Nanotubes Research Articles

Phase-Transition-Promoted Thermoelectric Textiles Based on Twin Surface-Modified CNT Fibers.

With the fast development of new science and technology, wearable devices are in great demand in modern human daily life. However, the energy problem is a long-lasting issue to achieve real smart, wearable, and portable devices. Flexible thermoelectric generators (TEGs) based on thermoelectric conversion systems can convert body waste heat into electricity with excellent flexibility and wearability, which shows a new direction to solving this issue. Here in this work, polyethylenimine (PEI) and gold nanoparticles (Au NPs) twin surface-modified carbon nanotube fibers (CNTFs) were designed and prepared to fabricate thermoelectric textiles (TET) with high performance, good air stability, and high-efficiency power generation. To better utilize the heat emitted by the human body, microencapsulated phase change materials (MPCM) were coated on the hot end of the TET to achieve the phase-transition-promoted TET. MPCM-coated TET device could generate 25.7% more energy than the untreated control device, which indicates the great potential of the phase-transition-promoted TET.

Functionalization of Carbon Nanotubes in Polystyrene and Properties of Their Composites: A Review.

The inherent π-π interfacial interaction between carbon nanotubes (CNTs) and polystyrene (PS) makes the CNT/PS composite a representative thermoplastic nanocomposite. However, the strong van der Waals force among CNTs poses challenges to achieving effective dispersion. This review provides an overview of various CNT functionalization methods for CNT/PS composites, encompassing covalent grafting with PS-related polymers and non-covalent modification. A focus in this section involves the pre-introduction surface modification of CNTs with PS or PS-related polymers, substantially enhancing both CNT dispersibility and interfacial compatibility within the PS matrix. Furthermore, a comprehensive summary of the mechanical, electrical, thermal, and electromagnetic shielding properties of CNT/PS nanocomposites is provided, offering an overall understanding of this material. The surface modification methods of CNTs reviewed in this paper can be extended to carbon material/aromatic polymer composites, assisting researchers in customizing the optimal surface modification methods for CNTs, maximizing their dispersibility, and fully unleashing the various properties of CNTs/polymer composites. Additionally, high-performance CNTs/PS composites prepared using appropriate CNT modification methods have potential applications in areas such as electronic devices, sensors, and energy storage and conversion.

Surface modification of carbon nanotubes and their nanocomposites for fuel cell applications: A review

<abstract> <p>Carbon nanotubes (CNTs) have drawn great attention as potential materials for energy conversion and storage systems such as batteries, supercapacitors, and fuel cells. Among these energy conversion and storage systems, the fuel cells had stood out owing to their high-power density, energy conversion efficiency and zero greenhouse gasses emission. In fuel cells, CNTs have been widely studied as catalyst support, bipolar plates and electrode material due to their outstanding mechanical strength, chemical stability, electrical and thermal conductivity, and high specific surface area. The use of CNT has been shown to enhance the electrocatalytic performance of the catalyst, corrosion resistivity, improve the transmission performance of the fuel cell and reduce the cost of fuel cells. The use of CNTs in fuel cells has drastically reduced the use of noble metals. However, the major drawback to the utilization of pristine CNTs in fuel cells are; poor dispersion, agglomeration, and insolubility of CNTs in most solvents. Surface engineering of CNTs and CNT nanocomposites has proven to remarkably remedy these challenges and significantly enhanced the electrochemical performance of fuel cells. This review discusses the different methods of surface modification of CNTs and their nanocomposite utilized in fuel cell applications. The effect of CNTs in improving the performance of fuel cell catalyst, membrane electrode assembly and bipolar plates of fuel cells. The interaction between the CNTs catalyst support and the catalyst is also reviewed. Lastly, the authors outlined the challenges and recommendations for future study of surface functionalized CNTs composite for fuel cell application.</p> </abstract>

Fiber, monolithic fiber and twisted fiber structures: efficient microwave absorption via surface-modified carbon nanotube buckypaper/silicon carbide-based self-sealing layered composites

A variety of self-sealing layered fiber substrates are constructed, and the substrates are converted into absorbers by cladding modification. Microwaves are scattered in all directions at multiple angles in the self-sealing layered fiber structures.

Surface-Modified Carbon Nanotubes with Ultrathin Co3O4 Layer for Enhanced Oxygen Evolution Reaction.

Alkaline water electrolysis is a vital technology for sustainable and efficient hydrogen production. However, the oxygen evolution reaction (OER) at the anode suffers from sluggish kinetics, requiring overpotential. Precious metal-based electrocatalysts are commonly used but face limitations in cost and availability. Carbon nanostructures, such as carbon nanotubes (CNTs), offer promising alternatives due to their abundant active sites and efficient charge-transfer properties. Surface modification of CNTs through techniques such as pulsed laser ablation in liquid media (PLAL) can enhance their catalytic performance. In this study, we investigate the role of surface-modified carbon (SMC) as a support to increase the active sites of transition metal-based electrocatalysts and its impact on electrocatalytic performance for the OER. We focus on Co3O4@SMC heterostructures, where an ultrathin layer of Co3O4 is deposited onto SMCs using a combination of PLAL and atomic layer deposition. A comparative analysis with aggregated Co3O4 and Co3O4@pristine CNTs reveals the superior OER performance of Co3O4@SMC. The optimized Co3O4@SMC exhibits a 25.6% reduction in overpotential, a lower Tafel slope, and a significantly higher turnover frequency (TOF) in alkaline water splitting. The experimental results, combined with density functional theory (DFT) calculations, indicate that these improvements can be attributed to the high electrocatalytic activity of Co3O4 as active sites achieved through the homogeneous distribution on SMCs. The experimental methodology, morphology, composition, and their correlation with activity and stability of Co3O4@SMC for the OER in alkaline media are discussed in detail. This study contributes to the understanding of SMC-based heterostructures and their potential for enhancing electrocatalytic performance in alkaline water electrolysis.

Structure Design, Surface Modification, and Application of CNT Microwave‐Absorbing Composites

AbstractElectromagnetic (EM) contamination has now become a non‐negligible problem. To solve the EM contamination problem, it is imperative to develop high‐efficiency absorption materials with thin thickness, light weight, strong absorption properties, and broad absorption bands. Carbon nanotubes (CNTs) have a special helical structure and chirality, which will lead to special EM effects and therefore can absorb EM microwaves through magnetic polarization attenuation such as hysteresis loss, domain wall resonance, and aftereffect loss. Moreover, they have the characteristics of light weight, good compatibility, wide absorption frequency band, and high electrical loss angle tangent. In this paper, the different structures of CNT microwave‐absorbing composites are reviewed and the effects of the composite structures on the microwave‐absorbing properties are systematically discussed. The methods and mechanisms of surface modification of CNT absorber composites and the effects of modification on the absorber properties are summarized in detail. The progress of two specific CNT microwave‐absorbing composites, namely flexible and high‐temperature microwave‐absorbing composites, is briefly described. The shortcomings and challenges in the application of CNT microwave‐absorbing composites are described and future research directions for CNT microwave‐absorbing composites are explored.

Retracted: Effect of Surface Modification of Carbon Nanotubes on the Properties of High-Strength and High-Conductivity Copper Matrix Composites

Retracted: Effect of Surface Modification of Carbon Nanotubes on the Properties of High-Strength and High-Conductivity Copper Matrix Composites

Cobalt Ferrite Surface-Modified Carbon Nanotube Fibers as an Efficient and Flexible Electrode for Overall Electrochemical Water Splitting Reactions.

One of the most practical and environmentally friendly ways to deal with the energy crises and global warming is to produce hydrogen as clean fuel by splitting water. The central obstacle for electrochemical water splitting is the use of expensive metal-based catalysts. For electrocatalytic hydrogen production, it is essential to fabricate an efficient catalyst for the counterpart oxygen evolution reaction (OER), which is a four-electron-transfer sluggish process. Here in this study, we have successfully fabricated cobalt-based ferrite nanoparticles over the surface of carbon nanotube fiber (CNTF) that was utilized as flexible anode materials for the OER and overall electrochemical water splitting reactions. Scanning electron microscopy images with elemental mapping showed the growth of nanoparticles over CNTF, while electrochemical characterization exhibited excellent electrocatalytic performance. Linear sweep voltammetry revealed the reduced overpotential value (260 mV@η10mAcm-2) with a small Tafel slope of 149 mV dec-1. Boosted electrochemical double layer capacitance (0.87 mF cm-2) for the modified electrode also reflects the higher surface area as compared to pristine CNTF (Cdl = 0.022 mF cm-2). Charge transfer resistance for the surface-modified CNTF showed the lower diameter in the Nyquist plot and was consequently associated with the better Faradaic process at the electrode/electrolyte interface. Overall, the as-fabricated electrode could be a promising alternative for the efficient electrochemical water splitting reaction as compared to expensive metal-based electrocatalysts.

Surface modified carbon nanotubes fiber as flexible bifunctional electrocatalyst for overall electrochemical water splitting reactions

Electrocatalytic water splitting is regarded as a promising approach to produce hydrogen, which is a clean and renewable fuel. The process is mainly constrained due to the sluggish proton-coupled four-electrode transfer process at the anode for oxygen evolution reaction (OER) with high overpotential requirement. Herein this work, we used a one-step hydrothermal method for the in-situ synthesis of CoSe nanoparticles over the surface of carbon nanotube-based fiber (CNTs fiber) and utilized it as a bifunctional electrocatalyst for the electrochemical water splitting process. Surface-modified fiber showed excellent performance towards OER with a low overpotential (η10 = 414 mV) and Tafel slope (77 mVdec−1). We also exploited the same material as cathode, which exhibited an excellent hydrogen evolution reaction (HER) at the counterpart with improved catalytic performance as compared to bare CNTs materials. During the HER process in the cathodic potential region, the electrocatalyst displayed a current density of 10 mAcm−2 at an overpotential of 496 mV. Furthermore, the electrocatalyst exhibited excellent performance during the testing for the overall water splitting. The outcomes reveal that the fabricated electrode can be potentially applied as an efficient and flexible electrode to derive the hydrogen as fuels during the overall electrochemical water splitting reaction.

Investigation of the effect of adding carbon nanotubes, lower and higher level alcohol additives, in Yellow oleander methyl ester-diesel blend on diesel engine performance

ABSTRACT The current study is to determine the overall performance of a compression ignition engine (CI) employing a B30 (30% Yellow Oleander Methyl Ester (YOME) and 70% diesel) sample including nano and alcohol additives. Initially, the surface-modified carbon nanotubes (CNTs) (at a dosage of 60 mg/L) are sonicated in the B30 blend for 30 mins at 40 kHz and termed B30CNTs60. It was found to be quite stable as evidenced by characterization. The B30CNTs60 blend is then blended with a fixed volume (10%) of n-Butanol, iso-Butanol, and Dimethyl Carbonate (DMC), and referred to as B30CNTs60+n-Butanol10%, B30CNTs60+iso-Butanol10%, and B30CNTs60+DMC 10%. The physicochemical properties of all fuel samples met ASTM criteria and samples were experimented on a 1-cylinder, 4-stroke diesel engine under varying loads. The results revealed that the B30CNTs60+DMC 10% blend enhanced heat release rate (HRR), cylinder pressure (CP), and brake thermal efficiency (BTE) by 11.2%, 8.64%, and 11.92%, respectively. Furthermore, with B30CNTs60+DMC 10% blend, the combustion duration, brake specific fuel consumption (BSFC), carbon monoxide (CO), hydrocarbons (HC), carbon dioxide (CO2), nitrogen oxide (NOx), and smoke opacity were reduced by 10.9%, 15.62%, 18.24%, 18.78%, 8.12%, 6.75%, and 10.92% respectively. Finally, the B30CNTs60+DMC 10% blend was suggested to use in CI engines.

Enhanced the properties of carbon‐paste nanocomposite by carboxylation of multi‐walled carbon nanotubes

AbstractIn the present study, attempts were made to manufacture innovative conducting polymer nanocomposites (CPCs) with high performance, low cost, and appropriate electrical, mechanical, and thermal properties. However, one of the main challenges in creating CPCs is the tendency of nanofillers to agglomerate and accumulate, resulting in a decrease in the electrical properties and performance of CPCs. To address this issue, the study developed an efficient and eco‐friendly CPC using carboxymethyl cellulose (CMC) as a binder and carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) as nanofillers. The study employed a chemical functionalization method to modify CNTs and enhance their compatibility and dispersion properties in the CMC matrix. The prepared CPCs were characterized using various techniques, including Fourier‐transform infrared spectroscopy, x‐ray diffraction, and field emission scanning electron microscopy. The results showed an improvement in homogeneity and surface cohesion between CMC and O‐CNTs through chemical surface modification of CNTs via carboxylic acid functional groups. The study observed good dispersion of nanofillers without any aggregation of the CMC/GNP/O‐CNT compared with the nontreated CMC/GNP/CNT composite. While a decrease in the degree of crystallinity was observed, conductivity increased for the CPC containing oxidized CNTs. The study found that the highest conductivity of ~112 S/m was obtained for D‐CMC/GNP/O‐CNT with 25 wt% of O‐CNT, while the maximum conductivity of D‐CMC/GNP/CNT was ~80 S/m with 35 wt% of CNTs. Additionally, the study observed an improvement in electrochemical properties after treatment of CNTs in the form of higher cathodic current in cyclic voltammetry and lower charge transfer resistance in impedance spectroscopy of D‐CMC/GNP/O‐CNT35 compared to untreated one.Highlights Preparation of new conductive nanocomposite consisting of CMC, CNTs, and GNPs. Carboxylation of CNTs to improve O‐CNT and CMC intermolecular interaction CMC/GNP/O‐CNT is 40% more conductive than unmodified CNT nanocomposite. Higher thermal stability and mechanical properties were observed by using O‐CNT. O‐CNT caused higher current density and lower electron transfer resistance for CPCs.

A highly stretchable carbon nanotube/reduced graphene oxide/ poly(dimethylsiloxane) composite with high thermal conductivity as a flexible strain sensor

Carbon nanotube (CNT) is an important filler for preparing poly(dimethylsiloxane) (PDMS)-based composite sensors with high thermal conductivity. However, CNT encounters challenges in terms of dispersion within the polymer matrix. In this work, a combined strategy was proposed to improve the dispersion of CNT, involving surface modification of CNT, CNT-reduced graphene oxide (rGO) hybridization and in-situ cross-linking of PDMS in a solution. The in-situ cross-linking of PDMS contributed to an increase in elongation at break, coupled with a reduction in the modulus of the resulting in-situ crosslinked PDMS/m-CNT@rGO (S-PDMS/m-CNT@rGO) composites. Through the implementation of this strategy, the dispersion of CNT within the PDMS matrix was enhanced, simultaneously facilitating the establishment of filler networks. At the filler content of 10.0 wt%, the thermal conductivity of the S-PDMS/m-CNT@rGO composite increased to 1.06 W/(m·K) and the electrical conductivity increased to 4.51 × 10−3 S/cm. The S-PDMS/m-CNT@rGO composite had a low percolation threshold which was 0.35 wt%. When utilized as a strain sensor, the S-PDMS/m-CNT@rGO composite exhibited high sensitivity, good repeatability and stability in monitoring human motion.

A novel Cr2O3 coated CNTs system: Synthesis, microstructure regulation, and characterization

Surface modification is an attractive strategy for expanding, improving, or altering the properties and functions of carbon nanotubes (CNTs), which opens up a broad range of novel applications. Herein, a simple, and efficient approach for the synthesis of the Cr2O3 coated CNTs system was developed, and the morphologies and microstructures of the coating on CNTs along with annealing temperature were systematically investigated. It was found the continuous amorphous (Cr2O3)1/2·(H2O)3/2 coating with a thickness of about 3–4 nm can be decorated onto CNTs with the applied coating processes, and which can be transformed into continuous amorphous Cr2O3 coating after annealing at 500 °C for 0.5 h. With further increasing the annealing temperature to 700 °C, nano Cr2O3 particles with high crystallinity were formed at the expense of amorphous Cr2O3 coating, and the coating on the surface of CNTs can be completely consumed for transforming into crystalline Cr2O3 nanoparticles when the annealing temperature is up to 800 °C. The findings provide important guidance for the surface modification of CNTs and lay the foundation for the industrial application of the novel Cr2O3 coated CNTs.

Laser-driven formation of ZnSnO3/CNT heterostructure and its critical role in boosting performance of the triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) as energy harvesters have been extensively investigated due to their ability to convert mechanical energy to electricity through the effective coupling of triboelectrification and electrostatic induction. Herein, we introduce polydimethylsiloxane (PDMS)-based TENG prepared using ZnSnO3 (ZTO) nanostructure on surface-modified carbon nanotubes (SMCs), which shows high power density suitable to different types of practical applications in energy harvesting and self-power system. TENG with 0.3 wt% ZTO-SMC exhibits an output voltage of 665.63 V and a current density of 137.08 mA m−2, corresponding to improvements of 295% and 453%, respectively, with those of a pristine PDMS-based TENG. The peak power density of the TENG is 10.57 W m−2 at a load resistance of 7 MΩ. The formation mechanism of ZTO on the SMCs (ZTO-SMC) and its effect on the TENG performance are demonstrated using density functional theory calculations. It is demonstrated that the enhanced output performance of the PDMS-based TENG using the ZTO-SMC is attributed to the synergetic effect of the enhanced dielectric constant, press-induced polarization, and effective frictional area in the triboelectric layer. This work gives a scientific and technical understanding of not only the formation of heterostructure through interface nanoengineering but also the development of polymer-based TENGs with enhanced triboelectric performance for use in energy harvesting and self-powered systems.

Surface Modification of Carbon Nanotubes in Silicone–Polyurethane for Improved Mechanical and Anticorrosion Properties

Carbon nanotubes (CNT) were dispersed into homemade silicone–polyurethane (SPU) resin in order to enhance their mechanical and anticorrosion ability. Before mixing with SPU, CNT were modified by four different approaches to improve their dispersion in SPU, and the surface of CNT were covered by SiO2–TiO2 nanoparticles, -NH2 groups, epoxy groups or isocyanate groups, respectively. The structures of the modified CNTs were checked by XRD, FTIR, and SEM. After being dispersed in SPU to form a composite coating, the one with SiO2–TiO2 nanoparticles modified CNT exhibited the best mechanical properties and chemical resistance (low water absorption), and its corrosion current density (icorr) was only 9.246 × 10−9 A cm2, which is four orders of magnitude lower than the icorr value of the coating with unmodified CNT (1.599 × 10−5 A/cm2). This may be because the covered SiO2–TiO2 nanoparticle increased the roughness of the CNT surface, which can improve their dispersion in SPU resin.

Surface modification of carbon nanotubes by a bifunctional amine silane; effects on physical/mechanical/thermal properties of epoxy nanocomposite

Weak interfacial interactions between MWCNTs and epoxy matrix causes agglomeration of the nanotubes and declines in the nanocomposite performances. In this study, MWCNTs were surface modified by a bifunctional amino silane (i.e. Bis (3-triethoxysilylpropyl)amine) at different concentrations. The nanotubes were previously functionalized through acid oxidation to increase silane grafting ratio. The pure, functionalized and silanized carbon nanotubes were characterized to assess the success of silane grafting. The pure and modified nanotubes were applied at different contents (0.5, 1 and 2 wt%) to epoxy resin. The tensile, flexural and compressive properties of the nanocomposites were evaluated. The nanocomposites were also characterized using water contact angle test, DSC, DMTA and FE-SEM/EDS analysis. It was observed that silanization of nanotubes caused considerable increment (32°) in the water contact angle of epoxy films. The results showed that incorporating the pure nanotubes (at 0.5 wt%) to epoxy resin enhanced the mechanical strengths but decreased the modulus of the epoxy sample. It was found that incorporating 0.5 wt% of modified MWCNT into epoxy binder caused 33, 53 and 40 % improvement in the tensile, flexural and compressive strengths and 56, 85 and 110 % increment in the tensile, flexural and compressive modulus compared to the pure MWCNT containing nanocomposite. The modified MWCNTs participated in curing of epoxy resin through reaction of silane amide groups with resin epoxide groups that this increased enthalpy of curing up to 25 %.

"Setaria viridis"-like cobalt complex derived Co/N-doped carbon nanotubes as efficient ORR/OER electrocatalysts for long-life rechargeable Zn-air batteries.

The development of efficient and facile strategies to prepare metal and nitrogen codoped carbon (M-N-C) materials as oxygen electrocatalysts in rechargeable Zn-air batteries with high performance and a long life is challenging. Herein, we report a simple route to synthesize cobalt and nitrogen codoped carbon nanotubes (denoted as Co/N-CNT) as bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries (ZABs). The Co/N-CNT are fabricated through the surface modification of carbon nanotubes with cobalt salt and melamine followed by pyrolysis, which delivers outstanding oxygen reduction/evolution reaction (ORR/OER) activity with a low overall potential gap (ΔE = 0.77 V) and remarkable durability. The home-made Zn-air batteries exhibit a high power density (130 mW cm-2vs. 82 mW cm-2), a large specific capacity of (864 mA h g-1Znvs. 785 mA h g-1Zn), and a long cycling life (1200 h vs. 60 h) in both aqueous and solid media. This work opens an avenue for the reasonable surface modification of carbon nanotubes with various metals and heteroatoms to achieve high-performance electrocatalysts for clean and sustainable energy conversion and storage devices.

Amphiphilic silicones for the facile dispersion of carbon nanotubes and formation of soft skin electrodes.

Flexible, dry skin electrodes represent a potentially superior alternative to standard Ag/AgCl metal electrodes for wearable devices used in long-term monitoring. Herein, such electrodes were formed using a facile method for dispersing carbon nanotubes (CNTs) in a silicone matrix using custom amphiphilic dispersive additives (DSPAs). Using only brief mixing and without the use of solvents or surface modification of CNTs, twelve poly(ethylene oxide)-silanes (PEO-SAs) of varying crosslinkability, architecture, siloxane tether length, and molar ratio of siloxane:PEO were combined with an addition cure silicone and CNTs. Nearly all PEO-SA modified silicone-CNT composites demonstrated improved conductivity compared to the unmodified composite. Best conductivities correlated to composites prepared with PEO-SAs that formed micelles of particular sizes (d ~ 200 - 300 nm) and coincided to PEO-SAs with a siloxane:PEO molar ratio of ~ 0.75 - 3.00. Superior dispersion of CNT by such PEO-SAs was exemplified by scanning electron microscopy (SEM). Advantageously, modified composites retained their moduli, rather than becoming more rigid. Resultant electrodes fabricated with modified composites showed skin-electrode impedance comparable to that of Ag/AgCl electrodes. Combined, these results demonstrate the potential of silicone-CNT composites prepared with PEO-SA DSPAs as flexible, dry electrodes as a superior alternative to traditional electrodes.

Surface Modification of Carbon Nanotubes by Ar Plasma Jet

Atmospheric pressure low temperature plasma jet (APPJ) is a technical direction that has attracted much attention in recent years. In this paper, argon is used as the working gas to produce highly active ions through funnel shaped glass tubes to modify the surface of carbon nanotubes. After the carbon nanotubes treated for 4 mins, SEM, water contact angle and FTIR detection results were compared before and after the experiment. The results showed that the hydrophobicity of carbon nanotubes was enhanced and the surface dispersion was improved after DBD plasma jet treatment.

Preparation of N, O co-doped carbon nanotubes and activated carbon composites with hierarchical porous structure for CO2 adsorption by coal pyrolysis

Coal pyrolysis was employed to create nitrogen–oxygen co-doped CNTs/AC composites for CO2 adsorption in this work. In comparison to previous publications on carbon nanotube surface modification and direct fabrication of CO2 adsorption materials, the approach developed in this work is simpler, more cost-effective, and has a better CO2 adsorption capability. The synthesized functional composites have high specific surface area (1003–1443 m2/g), high oxygen content (16.1 %) and nitrogen content (2.37 %).Among them, NCNTs/AC-1 exhibited a CO2 adsorption capacity of 3.77 mmol/g and a high CO2/N2 selectivity (25.05) at 298 K and 1 bar. The adsorption behavior of NCNTs/AC-1 can be well described by the Freundlich model. The linear correlation between CO2 absorption capacity, micropore volume of specific size (V < 0.7 nm and V < 0.9 nm), O content and N content was investigated. At 298 K, the contribution of O content to CO2 adsorption is comparable to or even higher than that of N content. Interestingly, micropores in the range of V < 0.9 nm have a good correlation with CO2 adsorption capacity at 273 K. This study offers new perspectives for the high added value and environmental protection of bituminous coal.