Carbon Nanotube Substrate Research Articles

Modifying Nanocarbon Films with Switchable Dopant Molecules for the Detection of Aqueous Permanganate

Monitoring disinfectants is essential to maintain water free from pathogens. Permanganate (MnO4 -) is one of the commonly used disinfectants and is applied as potassium permanganate (KMnO4) solution in drinking water and wastewater treatment plants. It is used as a pre-oxidant at the beginning of the treatment process for the control of reduced iron (II) and manganese (II) concentration.1,2 Though dilute KMnO4 solutions are sometimes used as topical antiseptics and astringents, higher concentration (over 200 mg/L) can cause gastrointestinal distress.3 A Do Not Consume concentration of 7 mg/L KMnO4 is recommended based on clinical experience.3 Therefore, to ensure the proper level of permanganate during and after the water treatment process, it is necessary to monitor the concentration of permanganate.Current methods for permanganate detection focus on spectrophotometric measurements (direct and indirect). The direct method involves no additional chemical, however, lacks the suitability for the samples with less than 0.75 mg/L of MnO4 -.4 Indirect methods provide better sensitivity but require the need for reagents like NaI and ABTS (unstable).4 A sensitive single-particle-detection (SPD) method has been reported recently which uses dark-field optical microscopy on graphene nanoplatelets silver (GNP@Ag) core-shell nanoparticles, but, this method is quite complex and requires sample preparation before analysis.1 Moreover, these methods are unsuitable for the implementation in a treatment plant for the online monitoring of disinfectant.To tackle this problem, we introduced a chemiresistive sensing platform capable of quantifying permanganate in aqueous media. Chemiresistive sensors are becoming popular in sensing due to their low cost, easy fabrication technique, and the ability to detect different analyte using appropriate ligand.5 Chemiresisive sensors have been reported before for the continuous measurement of free chlorine using carbon nanotube (CNT) substrate doped with redox-active aniline oligomer named phenyl capped aniline tetramer (PCAT).6 The sensor consists of two parallel electrodes connected by a layer of carbon nanotubes. Oligoanilines are immobilized on the substrate through noncovalent interactions. Oligoanilines are known to dope CNTs differently depending on which one of the three oxidation states they are in (fully reduced, half oxidized, and fully oxidized).7 , 8 Oxidation of this oligoaniline (PCAT) attached to the surface of CNT by permanganate molecule leads to a change in the oxidation state of the oligoaniline; this change in oxidation state in the molecule changes the doping characteristics of CNT leading to a change in resistance of the CNT film. This resistance change can be used to quantify the concentration of permanganate.9 This sensor can be reset with fresh water and reused for further analysis.Here we present a chemiresistive sensing array that can detect permanganate in the aqueous environment. We have functionalized the nanocarbon substrate with five different redox-active molecules. Four of them are pH-responsive and one is not responsive to the pH range used for the analysis. The sensors were tested for the range of 0.17 mg/L to 1.33 mg/L of MnO4 - at a pH range of 6.5 to 9.5. These redox-active molecules create active sites on the substrate, and when in contact with the analyte, dopant molecules attached on the surface react with analytes and give responses. These responses vary in magnitude depending on pH and the redox-active molecule. The sensor responses at different pHs were then analyzed using principal component analysis (PCA) to identify the pH of the permanganate solution. PCA analysis shows a clear separation of different pH solutions. We have therefore demonstrated a nanocarbon based sensing array that is not only capable of continuously measuring the low concentration of permanganate, but also the pH of the aqueous media.

A self-healing neutral aqueous rechargeable Zn/MnO2 battery based on modified carbon nanotubes substrate cathode

Rechargeable aqueous Zn/MnO2 batteries show great potential for grid-scale storage due to their low cost, high safety, and energy density, yet suffer from continuous capacity decay during operation. Therefore, this work proposes a capacity self-healing aqueous Zn/MnO2 (Zn/cCNTs-MnO2) battery using carboxyl-modified carbon nanotubes (cCNTs) as the cathode substrate, ZnSO4 + MnSO4 mixed aqueous solution as the electrolyte, and Zn foil as the anode. Based on the controllable electrodeposition reaction of MnO2, the specific capacity of Zn/cCNTs-MnO2 batteries can be achieved or recovered by operating several cycles under a low current density (0.1 mA cm−2). Then, the batteries can stably perform under a high current density (1 mA cm−2). By repeating the above steps, a capacity self-healing usage scheme was established, which can significantly improve the cycling performance of Zn/cCNTs-MnO2 batteries. Moreover, the results of the proposed Zn/cCNTs-MnO2 batteries verify the MnO2 electrodeposition mechanism and introduce a novel method for the development of durable aqueous rechargeable Zn/MnO2 batteries.

Enhanced Sodium‐Ion Storage Performance of a 2D MoS2 Anode Material Coated on Carbon Nanotubes

AbstractMolybdenum disulfide (MoS2) is considered a promising anode material for sodium‐ion batteries (SIBs). However, it suffers from poor kinetics and rapid capacity decay. In this work, a coaxial heterostructure composed of MoS2 nanosheets coated on carbon nanotubes (CNTs) is reported, where the MoS2 layers are less stacked at the surface of the CNTs substrate with an enhanced interlayer spacing, which is prepared through a simple one‐pot hydrothermal preparation. The MoS2@CNTs composite material is proven to have superior rate performance as an anode material for SIBs, which delivers 508, 418, 359, 305, 258, and 183 mAh/g at current densities of 0.1, 0.2, 0.5, 1, 2, and 5 A/g, respectively, together with excellent cycling stability to retain 360 mAh/g after 400 cycles at 0.5 A/g, owing to the robust combination of MoS2 and CNT components. This work offers a way to synthesize heterostructured composite materials with great performance superiority for large‐scale energy storage systems.

Plasma sprayed Lanthanum zirconate coating over additively manufactured carbon nanotube reinforced Ni-based Composite: Unique performance of thermal barrier coating system without bondcoat

For advanced thermal barrier coating (TBC) system in a modern aero and land based engine, there is pressing needs to impede the uncontrolled growth of thermally grown oxide (TGO) layers as well as the weight reduction of overall TBC system. To address both the issues, present study introduces a ‘bondcoat less’ TBC. Selective laser melting (SLM) technique has been used to fabricate two different substrates of composition NiCrAlY and NiCrAlY + 1 wt% carbon nanotube (CNT). Lanthanum zirconate (LZ) coating was deposited over the prepared substrate by plasma spraying technique. SLM processed NiCrAlY + 1 wt% CNT substrate showed the relatively higher increase in hardness and elastic modulus by 1.6 and 2.7 times, respectively. Top coat LZ coating and reinforced CNTs in NiCrAlY significantly suppressed the growth of the TGO layer at 1800 °C. It is shown that a fine microstructure, absence of pores in the coating and addition of CNTs in conjunction prevent the diffusion of the reactive species Al, Cr, Y from the NiCrAlY substrate towards the coating interface. Further, LZ coating despotised over NiCrAlY + 1 wt% CNT substrate was intact even after 48 cycles during the thermal shock resistance performed at 1800 °C.

Hollow Co3O4@N-doped carbon nanocrystals anchored on carbon nanotubes for freestanding anode with superior Li/Na storage performance

A template-free strategy is developed to construct a composite of hollow Co3O4 nanocrystals with N-doped carbon and carbon nanotubes (CNTs) as freestanding anodes for Li and Na ion batteries (LIBs/NIBs) via a chemical precipitation and subsequent two-step annealing. In this composite, the N-doped carbon coated hollow Co3O4 nanocrystals have a average diameter of 12 nm and are anchored tightly on highly conductive CNT substrates. Such nanocomposite possesses large specific surface area to supply ample active sites, highly conductive carbon networks to enhance electric conductivity, short ion diffusion distance to improve ion transport, and large interior space to accommodate volume expansion during repeatedly electrochemical reaction. Furthermore, kinetic analysis reveal that pseudocapacitive-controlled Li/Na storages plays a vital role. The freestanding composite as a anode for the LIBs exhibits large reversible capacity (1468 mAh g−1 after 130 cycles at 0.2 A g−1), superior rate performance (271 mAh g−1 at 12.5 A g−1) and good cyclic stability (905 mAh g−1 after 350 cycles at 1.0 A g−1). For the NIBs, the freestanding composite delivers attractive rate performance (104 mAh g−1 at 10 A g−1) and long cyclic performance (189 mAh g−1 after 400 cycles at 2.0 A g−1). Moreover, the assembled Li/Na full cell using the freestanding composite as anodes and LiFePO4 (for LIBs) and Na3V2(PO4)3 (For NIBs) as the cathodes display superior electrochemical performances. Our results suggest the prepared freestanding composite has a highly promising application in high-performance LIBs/NIBs.

Polymer interfaces with carbon nanostructures: First principles density functional theory and molecular dynamics study of polyetheretherketone adsorption on graphene and nanotubes

The interface of polyetheretherketone (PEEK) with carbon nanotubes (CNTs) and graphene is investigated using density functional theory and molecular dynamics within the REAXFF-lg interatomic interaction framework. The dependence of PEEK adsorption energy on the polymer chain length, temperature, starting adsorption configuration of the fully stretched conformation, and on the nature of the substrate was investigated. Overall, the interface between graphene and the polymers yield larger adsorption energies than the CNTs. Adsorption energies decrease with increasing temperature while for the CNT substrates, there is a slight dependence on the initial relative orientation between the nanotubes and the extended polymer chain. This is the first study on this interface, to the best of the authors’ knowledge, with such a wide spectrum of relevant variables.

Substrate adhesion evolves non-monotonically with processing time in millimeter-scale aligned carbon nanotube arrays.

The advantageous intrinsic and scale-dependent properties of aligned nanofibers (NFs) and their assembly into 3D architectures motivate their use as dry adhesives and shape-engineerable materials. While controlling NF-substrate adhesion is critical for scaled manufacturing and application-specific performance, current understanding of how this property evolves with processing conditions is limited. In this report, we introduce substrate adhesion predictive capabilities by using an exemplary array of NFs, aligned carbon nanotubes (CNTs), studied as a function of their processing. Substrate adhesion is found to scale non-monotonically with process time in a hydrocarbon environment and is investigated via the tensile pull-off of mm-scale CNT arrays from their growth substrate. CNT synthesis follows two regimes: Mode I ('Growth') and Mode II ('Post-Growth'), separated by growth termination. Within 10 minutes of post-growth, experiments and modeling indicate an order-of-magnitude increase in CNT array-substrate adhesion strength (∼40 to 285 kPa) and effective elastic array modulus (∼6 to 47 MPa), and a two-orders-of-magnitude increase in the single CNT-substrate adhesion force (∼0.190 to 12.3 nN) and work of adhesion (∼0.07 to 1.5 J m-2), where the iron catalyst is found to remain on the substrate. Growth number decay in Mode I and carbon accumulation in Mode II contribute to the mechanical response, which may imply a change in the deformation mechanism. Predictive capabilities of the model are assessed for previously studied NF arrays, suggesting that the current framework can enable the future design and manufacture of high-value NF array applications.

Self-Healing, Improved Efficiency Solid State Rechargeable Li/I2 Based Battery

Solid state electrolytes are receiving significant interest due to the prospect of improved safety, however, addressing the incidence and consequence of internal short circuits remains an important issue. Herein, a battery based on a LiI-LiI(HPN)2 solid state electrolyte demonstrated self-healing after internal shorting where the cells recovered and continued to cycle effectively. The functional rechargeable electrochemistry of the self-forming Li/I2-based battery was investigated through interfacial modification by inclusion of Li metal (at the negative interface), and/or fabricated carbon nanotube substrates at the positive interface. A cell design with lithium metal at the negative and a carbon substrate at the positive interface produced Coulombic efficiencies > 90% over 60 cycles. Finally, the beneficial effects of moderately elevated temperature were established where a 10 °C temperature increase led to ∼5× lower resistance.

Formation and electrochemical properties of multiwalled carbon nanotubes and polypyrrole composite with (n-Oc4N)Br binder

The electrochemical properties of a three-component composite containing polypyrrole, multiwalled carbon nanotubes and tetra(n-octyl)ammonium bromide as a binder have been investigated. The electrochemical behavior of this system depends on the relative amounts of the components within the composite. In the positive potential range, pseudo-capacitive behavior related to the polypyrrole oxidation is observed. The capacitance is enhanced due to the large surface area of the carbon nanotube substrate. Additionally, a contribution of double layer capacitance of multiwalled carbon nanotubes component leads to the capacitance increase. In consequence, high specific capacitance of approximately 600 F g−1 was obtained for this material. This value is about three times higher in comparison for the polymer deposited at the surface of bare gold electrode. The presence of tetra(n-octyl)ammonium bromide enhances the electrochemical and mechanical stability of the composite. The capacitance behavior of ternary composite is also more stable during cyclic charging/discharging processes in comparison to the polypyrrole film or polypyrrole/multiwalled carbon nanotube composite.

Study on the interfacial thermal resistance between CNTs and Al with a TTM-MD model

Interfacial thermal resistance between adjacent parts is important in the design of electronics and MEMS/NEMS devices as well as packaging. In this paper, the two-temperature model (TTM) along with non-equilibrium molecular dynamics (TTM-MD) is used to investigate the interfacial thermal resistance between carbon nanotube (CNT) and aluminium substrate. Factors including the direction of heat flow, temperature dependence and CNT engagement as well as the Al crystal orientation on the resultant interfacial thermal resistance are investigated. Thermal rectification can be observed due to the change of heat flow. Internal Al nanowire filling ratio and the crystal structures of Al substrate are found all significantly affecting the resultant interfacial thermal resistance.

Nanocable with thick active intermediate layer for stable and high-areal-capacity sodium storage

Developing electrodes cycling stably at high areal mass loadings is critical for sodium ion batteries (SIB) to reach practical applications, but remains challenging due to the larger ionic radius of Na + and generally sluggish electrochemical kinetics in thick electrodes. Consequently, most of the reported SIB electrodes exhibit low mass loadings (<1 mg cm −2 ) and thereby limited areal capacities. Here, we develop a hybrid network structure with orthorhombic Nb 2 O 5 coatings sandwiched between three-dimensional carbon nanotube (CNT) underlayers and outer carbon shells. By thickening Nb 2 O 5 intermediate layers, we can effectively raise the mass loadings of the sponge anodes with the electron and ion transport kinetics well maintained, owing to the highly conductive CNT substrate, porous network and carbon shell-enabled robust nanocable structures. As a result, the sponge anodes exhibit reversible areal capacities of 2.7 mAh cm −2 after 200 cycles at mass loadings up to 16.6 mg cm −2 , exceeding 9 times those of previous Nb 2 O 5 -based structures, and the achieved cycling stability is also among the best of the high-areal-capacity SIB anodes reported so far. Our work shows that thickening intermediate active coatings in rationally designed nanocable structures represents an effective way to promote their areal sodium storage performance for practical use. • Three-dimensional network structured electrode composed of interconnected nanocables. • Nanocable comprises carbon nanotube core, Nb 2 O 5 intermediate layer and carbon shell. • Thickening intermediate layer to raise electrodes mass loadings and areal capacities. • Robust hierarchical structure enables stable cycling performance for sodium storage.

Synergistic effect from coaxially integrated CNTs@MoS2/MoO2 composite enables fast and stable lithium storage

Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries. However, they suffer from rapid capacity decay and poor kinetics. Herein, we report on synergistic effect from structurally integrated coaxial [email protected]2/MoO2 composite material on lithium storage, in which MoS2/MoO2 nanosheets are conformally decorated on carbon nanotubes (CNTs). In-situ synchrotron X-ray diffraction measurement is performed to elucidate synergistic effect among three MoS2, MoO2 and CNTs components for lithium storage. Reaction mechanism exploration reveals that the MoO2 component undergoes reversible Li+ intercalation via forming a stable Li0.98MoO2 phase over a voltage range of 3.0 to 0.01 V vs. Li+/Li, without experiencing the conversion reaction into metallic Mo, which contributes to long-term stability during charge/discharge cycles. Meanwhile, lithium storage of MoS2 is through lithium and sulfur reversible reaction after the initial conversion reaction of lithiated MoS2 forming Li2S and Mo. The CNTs component enhances electronic conductivity and structural stability by minimizing volume change and reaction strains in the [email protected]2/MoO2 composite anode. A desired 68.2% capacity retention upon 2000 cycles at 10 A/g has been demonstrated for the [email protected]2/MoO2 anode, revealing prominent reaction kinetics and structural stability for fast and stable lithium storage, superior to various Mo-based anode materials previously reported. The findings from this study, with the unique insight into the role of structural integrity in combining MoS2/MoO2 materials with the CNTs substrate, offers a strategy for designing composite anode materials for superior lithium storage performance.

Direct growth of ordered N‐doped carbon nanotube arrays on carbon fiber cloth as a free‐standing and binder‐free air electrode for flexible quasi‐solid‐state rechargeable Zn‐Air batteries

AbstractThe development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of crucial importance for the rational design of flexible rechargeable Zn‐air batteries (ZABs). Considering their good elasticity, high conductivity, and superior thermal and chemical stability, carbon nanotubes have been widely used as a catalyst support in various electrocatalysts, while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials. Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long‐term operating stability, in particular in flexible devices, pure carbon electrocatalyst is highly appreciated. Herein, a free‐standing air electrode with cobalt nanoparticles encapsulated N‐codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two‐step in situ growth method. Such a carbon‐based electrode shows outstanding activity for both ORR and OER. The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions. Moreover, the polarization and round‐trip efficiency for the flexible battery is 0.67 V and 64.4% at 2 mA/cm2, respectively, even after being operated for 30 hours. This study provides a feasible way to design all carbon‐based free‐standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.

Development of CNT Film Alignment and Geometries for Neuronal Attachment and Efficient Signal Transfer between Neurons and Electrodes

Carbon nanotubes (CNTs) are widely used in neuroscience research for its excellent properties such as high conductivity, electrochemical stability, biocompatibility, mechanical compatibility with tissues, tunable mechanical and chemical properties. CNTs are investigating for its performance as neuronal scaffolds to support neural tissues, neuron growth and differentiation as well as neural stimulating and recording electrodes to control and monitor neural activity in both vitro and in vivo environments. Surprisingly neurons show a better interaction with CNTs when neurons are grown on CNT substrates. Previous research has shown neuronal differentiation on pristine CNT and CNT composites and the alignment of neurites on CNT substrates. Current research focus on interaction of neurons at the interface of pristine CNT films with aligned and cross hatch patterned CNT layers prepared from multi-walled CNT arrays. CNTs have nano scale surface roughness and contribution of alignment of CNTs can retain and adhere neurons without any adhesive proteins. As an initial step to study the interaction of neurons with CNT films, the effect of different CNT alignment on neuron adhesion and neurite development was chosen. PC12 cell line was used to study neuron adhesion and neurite alignment on CNT substrates. It is a commonly used neuronal cell model due to its ability to attain sympathetic neurons characteristics in the presence of nerve growth factor (NGF) in low serum medium. For the study, CNT films were prepared as aligned and in cross hatch pattern on PET sheets. After sterilization with UV irradiation, PC12 cells were seeded and cultured at a density of 20 000 cells/mL on CNT films and allowed to differentiate in NGF medium. For comparison poly l lysine (PLL) coated CNT films were used. Fig 1(Left) shows SEM image of a differentiating PC12 cell on PLL coated film of aligned CNTs and Fig 1(Right) shows SEM image of a differentiating PC12 cell on a crosshatch patterned CNT film with no adhesive coating. While neurites of PC12 cells align with the CNTs on aligned CNT film as states in the literature, pristine CNTs in crosshatch pattern were also able to hold the cells without any surface adhesive coating and allow differentiation of cells. Also PC12 cells tend to show random alignment on crosshatch patterned CNTs and adhere well due to higher degree of porosity and surface roughness. As pristine CNT films were able to hold PC12 cells, the interface properties will be further evaluated by impedance spectroscopy. Figure 1

Surface Engineering of Carbon Nanotubes with Inorganic-Organic Materials for Electrochemical Capacitors.

Composite electrodes comprised of inorganic-organic molecular materials are of great interest in applications such as electrochemical capacitors (ECs). ECs store and release charge via double layer capacitance (EDLC) or pseudocapacitance. The carbon materials used for EDLC has low capacitance, while pseudocapacitive materials such as redox active polymers or metal oxides have long term stability issues. Therefore, anchoring inorganic-organic materials on a carbon substrate can leverage the advantages of both EDLC and pseudocapacitance. Composite electrodes of kegging type polyoxometalates (POM) deposited on polydiallyldimethylammonium chloride (PDDA) via the layer-by-layer assembly has been well established and has shown great promise [1-3] . The issues are the limited operation window and the inert PDDA layer. Suitable alternatives that can complement the redox activity of POMs and enlarge the operating potential window are redox active polymers [4].The objectives of this work are to: 1) develop and optimize an electroactive inorganic-organic composite electrode based on a carbon nanotube (CNT) substrate modified with polyluminol (CpLum) and H5GeMo11VO40.24H2O (GeMo11V); 2) study the electrochemical behavior of the composite electrode with and without PDDA for electrochemical capacitors; and 3) investigate the interactions between each layer.GeMo11V was first deposited onto CNT using PDDA as an anchor. The vanadium atom in the kegging structure provided an additional electrochemical redox peak with improved capacitive behavior on the cyclic voltammogram (CV) as seen in figure 1. First, CpLum, and GeMo11V were applied on CNT (CNT-CpLum-GeMo11V), then co-deposited with PDDA (CNT-CpLum-PDDA-GeMo11V). For both composite electrodes, CpLum and GeMo11V contributed to the redox activity leading to a wider potential window. The CV of CNT-CpLum-GeMo11V showed more reversible redox peaks with a slightly reduced GeMo11V contribution compared to CNT-CpLum-PDDA-GeMo11V that had a smoother CV shape. The decrease in GeMo11V contribution was attributed to the smaller amount of positive charge within the CpLum chain needed to anchor the GeMo11V. Each layer had a distinct role in the inorganic-organic composite electrode. The CpLum polymer added additional redox activity in the higher potential range, while PDDA attracted and held the GeMo11V, which provided redox activity in the lower potential range. All three layers had a synergistic interaction and provided enhanced charge storage properties with good rate capability and cycling stability.REFERENCES 1. M. Genovese, Y. W. Foong and K. Lian, Electrochimica Acta, 199, 261 (2016).2. M. Genovese and K. Lian, Current Opinion in Solid State and Materials Science, 19, 126 (2015).3. M. Genovese, Y. W. Foong and K. Lian, Journal of The Electrochemical Society, 162, A5041 (2015).4. N. Casado, G. Hernández, H. Sardon and D. Mecerreyes, Progress in Polymer Science, 52, 107 (2016). Figure 1

Controlled short time large scale synthesis of magnetic cobalt nanoparticles on carbon nanotubes by flash annealing

Nanopatterned arrays of discrete cobalt nanostructures showing characteristic parameter-dependent sizes are formed from continuous thin films on a carbon nanotube substrate using millisecond pulsed intense UV light. The nanoparticles exhibit ferromagnetic behavior with magnetic remanence and coercivity depending on the particle size. The end-state particle size is shown to be a function of initial thin film thickness and excitation energy and is therefore tunable. The evolutionary process from continuous thin films to a discrete morphology is thermodynamically driven by the large surface energy difference between metastable thin films and the underlying carbon nanotube substrate. Evidence of the Danielson model of the dewetting process is observed. These arrays can find applications as platforms for the self-assembly of magnetically susceptible materials, such as iron or nickel nanostructures, into a conduction matrix for applications in energy extraction from a latent heat storage device.

Cobalt-Nickel Wrapped Hydroxyapatite Carbon Nanotubes as a New Catalyst in Oxygen Evolution Reaction in Alkaline Media

Introducing an inexpensive non-noble metal electrocatalyst is an ongoing challenge in oxygen evolution reaction (OER). Here, a bimetallic cobalt-nickel-based catalyst is introduced by metal loading over hydroxyapatite multiwalled carbon nanotube substrate (Co-Ni/HA-MWCNTs). The proposed catalyst is promising and inexpensive and could be favorably applied in water electrolyzing systems. The HA-MWCNTs substrate was produced via the solid-state approach and the loading of Ni and Co species was achieved via the simple impregnation process. Structural characterization of the catalyst was achieved using transmission electron microscopy (TEM), X-Ray diffraction (XRD), and energy-dispersive X-ray analysis (EDX). Electrochemical efficiency of the catalyst for the OER was concluded from low onset potential at 1.50 V (vs RHE) with Tafel slope of 41.8 mV dec−1. In comparison with the HA-free catalyst (Co-Ni/MWCNTs), the Co-Ni/HA-MWCNTs catalyst exhibits an excellent long-term stability up to 10,000 s to bear the current density of 10.0 mA cm−2.

Ag Nanostructures on Poly(3-hexylthiophene) and Semiconducting Single-Walled Carbon Nanotube Substrates for SERS Detection of Rhodamine B and Electrochemical Detection of Hydrogen Peroxide

Superstructures with controlled particle congregation exhibit an increasing influence on the properties of materials, thus tuning the nucleation and interaction of nanoparticles is important for th...

The Capacitive Behavior of Polyluminol on Carbon Nanotubes Electrodes

AbstractA polymerized luminol carbon nanotube (CNT) composite electrode was developed via an in situ chemical polymerization (CpLum) process. Density functional theory (DFT) simulation suggested the luminol molecules were preferentially aligned flat on the CNTs. This was further demonstrated through a morphological study, which showed the CpLum wrapped around each CNT homogeneously with an average thickness of 4.5±1.5 nm. The surface chemical analysis by X‐ray photoelectron spectroscopy (XPS) revealed a progressive increase in the nitrogen content and stabilized at 9 %. Deconvolution of the high‐resolution N 1s spectra suggested the presence of secondary and tertiary amine functional groups, which are the signatures of polymerized luminol. The composite electrodes exhibited a pseudocapacitive‐like behavior with 3.5 times increase in charge storage. The contributions from the CpLum coating and CNT substrate were differentiated and were further deconvoluted to quantify the capacitive charge storage of each component. The thin CpLum coating contributed 70 % of the total charge storage through pseudocapacitance. CpLum‐CNT electrodes also showed a high rate capability and good cycling stability, very promising for electrochemical capacitors.

In vitro proliferation and differentiation of canine bone marrow derived mesenchymal stem cells over hydroxyl functionalized CNT substrates

Nanotopography of culture substrate acts as a positive cue in cell-biomaterial based tissue regeneration. Considering the potentiality of carbon nanotubes (CNTs) this study was designed to evaluate its two functionalized form by an in vitro culture condition using canine mesenchymal stem cells as cellular model. Cells were isolated and its behaviour, proliferation and differentiation processes were elucidated onto CNT substrates. Beside the variations in cellular behaviour it was remarkably noted that even though proliferation was reduced but osteogenic and chondrogenic differentiation was enhanced over multi-walled CNTs, whereas neuronal differentiation was better supported by single walled CNTs as evidenced by our cytochemical, immunocytochemical, gene expression and flow cytometry assays. The former one was noticed more cytocompatible by our different apoptosis studies. The outcome of these experiments collectively indicated that hydroxylated functionalized CNTs could be a potential scaffold constituent for future experimentations as well as for the application in regenerative medicine.