Sidewalls Of Nanotubes Research Articles

CO2 Responsive Thin-Film Transistors Using Conjugated Polymer Complexes with Single-Walled Carbon Nanotubes.

Introduction of amidine groups within the side chains of a conjugated polyfluorene was carried out using copper-catalyzed azide-alkyne cycloaddition. The resulting polymer was shown to form strong supramolecular interactions with the sidewalls of single-walled carbon nanotubes (SWNTs), forming polymer-nanotube complexes that exhibited solubility in various organic solvents. It was shown that the polymer-SWNT complexes were responsive to CO2, where the amidine groups formed amidinium bicarbonate salts upon CO2 exposure, causing the polymer-SWNT complexes to precipitate. This reaction could be reversed by bubbling N2 through the solution, which caused the polymer-SWNT complexes to redissolve. Incorporation of the polymer-SWNT complexes within thin-film transistor (TFT) devices as the active layer resulted in a CO2-responsive TFT sensor. It was found that the sensory device underwent a reversible shift in its threshold voltage from 5 to -1 V as well as a 1 order of magnitude decrease in its on-current upon exposure to CO2. This work shows that conjugated polymer-wrapped SWNTs having sensory elements within the polymer side chain can be used as the active layer within functional SWNT-based TFT sensors.

Catch and release: Gold adsorption and sorbent electrochemical regeneration

Wastewater generated from e-waste leaching is rich in precious metals including gold, silver and platinum. Conventional precipitation and solvent extraction are chemically intensive separations with concerning environmental externalities. Sorbents, in particular carbon nanotubes, have low chemical consumption, and have shown promise for gold adsorption due to their high specific surface area and chemical functionalization potential. However, regenerating sorbents used to adsorb Au is hazardous requiring strong acids. Herein, we delineate the effect of various functional groups on the sidewalls of multiwall carbon nanotubes (MWCNTs) on gold adsorption, and we introduced an acid-free electrochemical technique for Au elution from MWCNTs. Pristine MWCNTs (P-MWCNTs), carboxylic functionalised MWCNTs (COOH-MWCNTs) and amide functionalised MWCNTs (NH2-MWCNTs) were compared for their affinity for Au adsorption from acidic AuCl4−solutions mimicking acidic e-waste leachate. Au adsorption affinity onto MWCNTs followed the order of P-MWCNT > NH2-MWCNT > COOH-MWCNTs. Au elution from Au-saturated MWCNTs was subsequently achieved up to 65%, using acid-free electrochemical desorption in neutral aqueous brine. The Au electro-desorption was shown to have a direct relationship with both the applied current and the mass of the Au adsorbed on the MWCNTs. This study demonstrates enhanced adsorption-based preconcentration of gold and acid-free regeneration of sorbents.

Raman Characterization of Guanine Functionalized SWCNTs

Single-walled carbon nanotubes (SWCNTs) have unique photophysical properties that render them an important class of materials for future nanoelectronics and bio-nano sensor applications. A method was recently discovered for making spatially patterned modifications to SWCNT band gaps and thereby modulating their electronic and optical properties in a controlled manner. The reaction used for this is called guanine functionalization.1 It is achieved by generating singlet oxygen in a dispersion of SWCNTs coated with single-stranded DNA, resulting in covalent bond formation between the guanine nucleobases in the DNA coatings and the nanotube sidewalls. Each of the many covalently bonded guanine sites acts as a weak exciton trap, causing red-shifted SWCNT emission and absorption spectra. Fluorescence spectroscopy shows that the extent of guanine functionalization can depend strongly on SWCNT structure, but spectral broadening can hamper the precise deconvolution of emission features of different (n,m) species. To track such covalent functionalization through Raman scattering, the D to G band ratios are commonly used as a measure of sp3 defect density and therefore of the functionalization extent. However, this conventional Raman method cannot show which (n,m) species in unsorted samples have been functionalized, because they all contribute to the D and G band signals. We will describe a novel Raman analysis based on the relative intensities of bands that have shifts located between the RBM and D regions. These Raman features are found to be diameter-specific, allowing estimation of (n,m)-resolved functionalization extents in unsorted SWCNT samples. In addition, we will present an assignment and interpretation of the relevant Raman features. Zheng, Y.; Bachilo, S. M.; Weisman, R. B., Controlled patterning of carbon nanotube energy levels by covalent DNA functionalization. ACS Nano 2019, 13, 8222-8228.

Voltammetric Evidence of Proton Transport through the Sidewalls of Single-Walled Carbon Nanotubes.

Understanding ion transport in solid materials is crucial in the design of electrochemical devices. Of particular interest in recent years is the study of ion transport across 2-dimensional, atomically thin crystals. In this contribution, we describe the use of a host-guest hybrid redox material based on polyoxometalates (POMs) encapsulated within the internal cavities of single-walled carbon nanotubes (SWNTs) as a model system for exploring ion transport across atomically thin structures. The nanotube sidewall creates a barrier between the redox-active molecules and bulk electrolytes, which can be probed by addressing the redox states of the POMs electrochemically. The electrochemical properties of the {POM}@SWNT system are strongly linked to the nature of the cation in the supporting electrolyte. While acidic electrolytes facilitate rapid, exhaustive, reversible electron transfer and stability during redox cycling, alkaline-salt electrolytes significantly limit redox switching of the encapsulated species. By "plugging" the {POM}@SWNT material with C60-fullerenes, we demonstrate that the primary mode of charge balancing is proton transport through the graphenic lattice of the SWNT sidewalls. Kinetic analysis reveals little kinetic isotope effect on the standard heterogeneous electron transfer rate constant, suggesting that ion transport through the sidewalls is not rate-limiting in our system. The unique capacity of protons and deuterons to travel through graphenic layers unlocks the redox chemistry of nanoconfined redox materials, with significant implications for the use of carbon-coated materials in applications ranging from electrocatalysis to energy storage and beyond.

Antiproliferative Activity of PEG-PEI-SWCNTs against AMJ13 Breast Cancer Cells

Single-walled carbon nanotubes (SWCNTs) involving polyethylene glycol (PEG) and polyethyleneimine (PEI), which contain amines, were produced and analyzed using X-ray diffraction (XRD), UV–vis spectroscopy, Raman spectroscopy (RS), and transmission electron microscopy (TEM) for the spectral and structural analyses of PEG-PEI-SWCNTs. PEG-PEI-SWCNTs demonstrated peaks using UV–vis spectroscopy at 300.98 nm, have a broad peak at 2θ = 23.51, linked to 002 with d-spacing (3.7816), and have crystalline sizes of 8.48 nm. In PEG-PEI-SWCNTs, TEM images demonstrated the accumulation of SWCNTs with PEG-PEI due to an increased main grain size with functionalization to 80.68 nm. The D and G bands in PEG-PEI-SWCNTs moved to 1,292 and 1,586 cm−1, respectively. SWCNTs are observed as a bundle of inhomogeneous, long-curved accumulates containing multitudes of tubes. The PEG-PEI-SWCNTs have a tubular structure that demonstrates particles scattered alongside the carbon nanotube sidewalls, which indicate that PEG and PEI are conjugated to the SWCNTs. Cytotoxicity evaluation of PEG-PEI-SWCNTs (6.25–100 µg/mL) in the breast cancer AMJ13 cell line was conducted for 24 and 72 hr, and the results showed enhanced toxicity to the tumor cells and decreased cytotoxicity against rhabdomyosarcoma (RD) normal cells.

Ortho-Substituted Aryldiazonium Design for the Defect Configuration-Controlled Photoluminescent Functionalization of Chiral Single-Walled Carbon Nanotubes.

Defect functionalization of single-walled carbon nanotubes (SWCNTs) by chemical modification is a promising strategy for near-infrared photoluminescence (NIR PL) generation at >1000 nm, which has advanced telecom and bio/medical applications. The covalent attachment of molecular reagents generates sp3-carbon defects in the sp2-carbon lattice of SWCNTs with bright red-shifted PL generation. Although the positional difference between proximal sp3-carbon defects, labeled as the defect binding configuration, can dominate NIR PL properties, the defect arrangement chemistry remains unexplored. Here, aryldiazonium reagents with π-conjugated ortho-substituents (phenyl and acetylene groups) were developed to introduce molecular interactions with nanotube sidewalls into the defect-formation chemical reaction. The functionalized chiral SWCNTs selectively emitted single defect PL in the wavelength range of ∼1230-1270 nm for (6,5) tubes, indicating the formation of an atypical binding configuration, different from those exhibited by typical aryl- or alkyl-functionalized chiral tubes emitting ∼1150 nm PL. Moreover, the acetylene-based substituent design enabled PL brightening and a subsequent molecular modification of the doped sites using click chemistry.

Exploring the Covalent Doping of Single-Wall Carbon Nanotubes Induced By Photoexcited Hypochlorite

Chemical functionalization of the sidewalls of single-wall carbon nanotubes remains a topic of current interest because it can modify and enhance nanotube optical properties. These modifications can shift SWCNT structure-specific optical transitions further into the near-infrared, which may prove useful for applications in bio-imaging or quantum information processing. Here we present a study on the use of photoexcited hypochlorite ions as a reactant to efficiently produce sparse oxygen-containing defects in SWCNTs. Our studies highlight the formation of new secondary reaction products in the absence of dissolved oxygen. These results in combination with quantum computations provide insight into the structure of the new photoadducts. Additionally, we find that product spectra depend on pH of the reacting system, implying more than one reaction pathway. This finding is supported by measurements of the effects of radical quenchers on product properties. Our results provide improved understanding and control of an important class of nanotube functionalization reactions.

Carbon Nanotubes from Synthesis to Picomolar Detection Electrochemical Sensors

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in this field has been the ability to conduct electrochemical studies selectively at the open-ends of CNTs, without measuring contributions from the sidewalls. This talk will discuss the synthesis and assembly of CNTs into electrochemical sensor where open-ended CNTs were employed for electrochemical measurements. The assembly employs drawable CNTs that minimize sample handling and contamination, in the attempt to preserve the pristine nature of CNTs. Highly densified multiwalled carbon nanotube (HD-CNT) fibers were embedded within a polymer matrix protecting the sidewalls and limiting the reactions to the tips of the CNTs. Cyclic voltammetry was employed to examine the electrochemical properties of open-ended CNTs using a conventional bulk electrochemical cell and scanning electrochemical cell microscopy (SECCM). This assemblies have shown to detect extremely low concentrations of Pb2+ in water, neurotransmitters, NADH, furosemide (diuretic drug), and the electrodes were tested with multiple electrochemical techniques.

Computational and structural study of titanium/carbon nanotube nanocomposite

In this study, the electronic structure and thermodynamic parameters of titanium doping at different locations of carbon nanotubes (6-6) have been investigated using density functional theory computational methods. The Ti prefers to be located near to vertex of the nanotube sidewall and at the central axis and leads to better structural stability and thermodynamic parameters than other sites. Then, the most stable and active structure for carbon monoxide adsorption was examined from two directions of oxygen and carbon atom, which is accompanied by hybridization and spatial repulsion. The results obtained from the energy level of the highest occupied HOMO orbital and the lowest occupied LUMO one and also NBO analysis indicated that the electron-accepting titanium metal (Mulliken charge for titanium atom above 0.5) has an empty orbital. Carbon monoxide gas is a donor of electron pairs. The adsorption of carbon monoxide from the oxygen atom side in the vertical state (IVA) on the surface of the nanotube doped with titanium was found to be the best.

Defect Etching in Carbon Nanotube Walls for Porous Carbon Nanoreactors: Implications for CO2 Sorption and the Hydrosilylation of Phenylacetylene.

A method of pore fabrication in the walls of carbon nanotubes has been developed, leading to porous nanotubes that have been filled with catalysts and utilized in liquid- and gas-phase reactions. Chromium oxide nanoparticles have been utilized as highly effective etchants of carbon nanotube sidewalls. Tuning the thermal profile and loading of this nanoscale oxidant, both of which influence the localized oxidation of the carbon, have allowed the controlled formation of defects and holes with openings of 40–60 nm, penetrating through several layers of the graphitic carbon nanotube sidewall, resulting in templated nanopore propagation. The porous carbon nanotubes have been demonstrated as catalytic nanoreactors, effectively stabilizing catalytic nanoparticles against agglomeration and modulating the reaction environment around active centers. CO2 sorption on ruthenium nanoparticles (RuNPs) inside nanoreactors led to distinctive surface-bound intermediates (such as carbonate species), compared to RuNPs on amorphous carbon. Introducing pores in nanoreactors modulates the strength of absorption of these intermediates, as they bond more strongly on RuNPs in porous nanoreactors as compared to the nanoreactors without pores. In the liquid-phase hydrosilylation of phenylacetylene, the confinement of Rh4(CO)12 catalyst centers within the porous nanoreactors changes the distribution of the products relative to those observed in the absence of the additional pores. These changes have been attributed to the enhanced local concentration of phenylacetylene and the environment in which the catalytic centers reside within the porous carbon host.

Selective adsorption and dissociation of NO, NO2, and N2O molecules on Si-doped haeckelite boron nitride nanotube: an investigation for sensitive molecular sensors and catalysts.

The current study describes the investigation of the adsorption NO, N2O, and NO2 on haeckelite boron nitride nanotube doped with Si (Si-doped haeck-BNNT) by means of density functional theory calculation (DFT). The obtained results confirmed the energetic stability of the optimized geometries and revealed that the adsorption of the gas molecules with the nanotube sidewall is a spontaneous process. The calculated work function of Si-doped haeck-BNNT in the presence of gas molecules is greater than that of a bare Si-doped haeck-BNNT sheet. The energy gap of the Si-doped haeck-BNNT is sensitive to the adsorption of the gas molecules, which implies possible future applications in gas sensors. For most of the adsorption configurations studied, the adsorption energies for the SiB-doped haeck-BNNT are higher than those for SiN-doped haeck-BNNTones. The N2O gas molecule is totally dissociated into N2 and O species through the adsorption process, while the other gas molecules retain their molecular forms. Thus, the SiN-doped haeck-BNNT is a likely catalyst for dissociation of the N2O gas molecule. Our findings divulge promising potential of the doped haeck-BNNT as a highly sensitive molecular sensor for NO and NO2 detection and a catalyst for N2O dissociation.

Ruthenium‐p‐cymene Complex Side‐Wall Covalently Bonded to Carbon Nanotubes as Efficient Hybrid Transfer Hydrogenation Catalyst

AbstractA half‐sandwich ruthenium‐p‐cymene organometallic complex has been immobilized at Single Walled Carbon Nanotubes (SWNT) sidewalls through a stepwise covalent chemistry protocol. The introduction of amino groups by means of diazonium‐chemistry protocols leads the grafting at the outer walls of the nanotubes. This hybrid material is active in the transfer hydrogenation of ketones to yield alcohols, using as hydrogen source 2‐propanol. SWNT−NH2−Ru presents a broad scope, performing the reaction under aerobic conditions and can be recycled over 9 consecutive reaction runs without losing activity or leaching ruthenium out. Comparison of the activity with related homogeneous catalysts reveals an improved performance due to the covalent bond between the metal and the material, achieving turnover frequencies as high as 192774 h−1.

Toward efficient enantioseparation of ibuprofen isomers using chiral BNNTs: Dispersion corrected DFT calculations and DFTB molecular dynamic simulations

The separation of drug enantiomers in pharmaceutical industry is one of great importance since most organic compounds are chiral. In this study, the separation of ibuprofen enantiomers and the interaction between right-handed (R) and left-handed (S) isomers of ibuprofen with the outer surface as well as internal sidewall of a chiral boron nitride nanotube (BNNT(10,5)) was evaluated. The geometry optimizations and total energy calculations were performed with DFT–D3/revPBE-GGA method for various adsorption configurations. Our first-principles findings showed that interaction strength of the incorporated enantiomers into the BNNTs was higher than ones adsorbed onto the outer surface of nanotube. Also, the interaction energy difference between two enantiomers interacting with inside and outside of the BNNT was about 0.63 and 1.25 kcal/mol, respectively. This finding indicated the more ability of outer surface of BNNT in efficient enantioseparation of Ibuprofen isomers rather than inner site. Furthermore, in order to model a realistic system, tight-binding density functional molecular dynamics (DFTB–MD) simulation was performed at room temperature, and the results were consisted with the DFT–D3 findings. The nudged elastic band (NEB) method was also used to evaluate the activation energy barrier for incorporation of ibuprofen into the BNNT cavity. Our molecular simulation findings are reliable to offer beneficial information about the potential application of chiral BNNTs in enantiomer molecules adsorption and separation.

Distortion of yttrium bisphthalocyanine (YPc2) upon noncovalent interaction with carbon nanotubes: A DFT study

We performed a DFT analysis of the changes in geometry and some electronic properties of yttrium bisphthalocyanine YPc2 when forming noncovalent hybrids with two single-walled carbon nanotube models, having armchair (ANT) and zigzag (ZNT) chiralities. The Perdew-Burke-Ernzerhof functional in combination with a long-range dispersion correction by Grimme (PBE-D) and the double numerical basis sets of variable size (DN, DND and DNP) was used. We found that YPc2 molecule suffers binding distortion in order to increase the area of contact with nanotube sidewall, which enhances interaction between the two components. YPc2 bonding is stronger with ZNT nanotube, of −43.8 kcal/mol, vs. −37.1 kcal/mol for YPc2 + ANT complex (as calculated with DNP basis set). The height of bisphthalocyanine molecule in the dyads dramatically increases compared to that calculated for isolated YPc2, whereas the calculated N-Y-N angles in YN4 coordination change very insignificantly. In all cases, a minor HOMO-LUMO gap narrowing is observed. For YPc2 + ANT the gap tends to match the one for isolated YPc2, whereas for YPc2 + ZNT it is much closer to the band gap of ZNT. The calculated HOMO, LUMO and spin density plots are analyzed.

The Influence of Reaction Time on Non-Covalent Functionalisation of P3HT/MWCNT Nanocomposites.

Non-covalent functionalisation of the carbon nanotube (CNT) sidewall through polymer wrapping is the key strategy for improving well-dispersed CNTs without persistent alteration of their electronic properties. In this work, the effect of reaction time on regioregular poly (3-hexylthiophene-2,5-diyl) (P3HT)-wrapped hydroxylated multi-walled CNT (MWCNT-OH) nanocomposites was investigated. Five different reaction times (24, 48, 72, 96, and 120 h) were conducted at room temperature in order to clearly determine the factors that influenced the quality of wrapped MWCNT-OH. Morphological analysis using Field Emission Scanning Electron Microscopic (FESEM) and High-Resolution Transmission Electron Microscope (HRTEM) analysis showed that P3HT successfully wrapped the MWCNT-OH sidewall, evidenced by the changes in the mean diameter size of the nanocomposites. Results obtained from Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) as well as Thermogravimetric Analysis (TGA) showed a significant effect of the wrapped polymer on the CNT sidewall as the reaction time increased. Overall, the method used during the preparation of P3HT-wrapped MWCNT-OH and the presented results significantly provided a bottom-up approach to determine the effect of different reaction times on polymer wrapping to further expand this material for novel applications, especially chemical sensors.

(Invited) Quantum Light Emission from Coupled Defect-States in DNA-Functionalized Carbon Nanotubes

Solid-state single-photon sources are the essential building block for quantum photonics and quantum information technologies. The report here illustrates an advanced perspective of implanting coupled fluorescent quantum defects in single-wall carbon nanotubes (SWCNTs) through chemical reactions between the nanotube sidewall and the guanine nucleotides in single-stranded DNA (ssDNA) that coats the nanotube. Through low-temperature photoluminescence spectroscopy and photon correlation experiments, we have revealed that multiple guanine defects within a single ssDNA strand couple together to form a cumulative deep trapping potential supporting a localized quantum state that is capable of room-temperature single-photon emission. Helical wrapping of multiple ssDNA strands in single nanotubes allows a series of exciton localization sites to be created along the length of the SWCNTs. Such unique exciton trapping potential landscape gives rise to previously inaccessible intrinsic emission characteristics including coupling of multiple spatially separated quantum emitters. Our joint experimental and computational studies together reveal quantum emission properties from multiple spatially patterned covalent defects in SWCNTs, identify capture of the band-edge exciton as the underlying cause of the cross-correlated photon emission and open a distinctive prospect for tailoring chemically altered nanotubes as quantum light emitters.

(Invited) Toward Spectral Homogeneity in Guanine Functionalized SWCNTs

Different chiralities of single-walled carbon nanotubes (SWCNTs) have distinct electronic and optical properties, with a range of band gaps that make them appropriate for several opto-electronic applications. Due to the unusually high mobility of charge carriers in SWCNTs,1 semiconducting SWCNTs may find use as logic gates in future high-speed nano-electronic circuits. With this in mind, controlled modulation of the optical and electronic properties of individual carbon nanotubes may be valuable in optoelectronic and nano-bioelectronic applications.It was recently discovered that when SWCNTs coated with single-stranded DNA are exposed to singlet oxygen, the guanine nucleobases in the DNA coatings form covalent bonds to the nanotube sidewalls.2 This alters the nanotube electronic and optical properties, allowing spatial and energetic control through selection of the DNA base sequence. However, the functionalized products display undesired spectral broadening interpreted as excess inhomogeneity compared to the pristine SWCNT reactants.Here we will present the results of efforts to understand and reduce this inhomogeneity. Our study has used molecular dynamics simulations of ssDNA – SWCNT hybrid structures, as well as analysis of experimental data. We have explored the effects of varied reaction conditions, including temperature, ionic strength, and pH on product yields and spectra. An unexpected inverse dependence of functionalization density on reaction temperature was uncovered. We will also present photophysical results extracted from spectral data via statistical modeling, including the energy depth of localized exciton quantum wells created by functionalization. The analysis points to fluorescence red shifts that reflect the random number of functionalization sites felt by excitons. Dürkop, T.; Getty, S. A.; Cobas, E.; Fuhrer, M. S. Extraordinary Mobility in Semiconducting Carbon Nanotubes. Nano Lett. 2004, 4, 35-39.Zheng, Y.; Bachilo, S. M.; Weisman, R. B. Controlled Patterning of Carbon Nanotube Energy Levels by Covalent DNA Functionalization. ACS Nano 2019, 13, 8222-8228.

Lithium-functionalized boron phosphide nanotubes (BPNTs) as an efficient hydrogen storage carrier

In this work we have carried out extensive Density Functional Theory (DFT) and ab-initio Molecular Dynamics (AIMD) simulations to study the structural and electronic properties, thermal stability, and the adsorption/desorption processes of hydrogen H2 molecules on Lithium (Li) functionalized one-dimensional boron phosphide nanotubes (BPNTs), for possible use as materials of H2-storage media. Our results show that Li atoms can be adsorbed on the hollow sites of (7,7)-BPNT with binding energy ranging from 1.69 eV, for one Li, to 1.65 eV/Li for 14 Li atoms adsorbed on (7,7)-BPNT. These large energies of Li prevent the formation of clusters on the nanotube sidewall. The investigation of the electronic behavior showed that (7.7)-BPNT semiconductor turns metallic upon the Li-adsorption. Furthermore, the average binding energy of H2-molecules adsorbed on nLi@BPNT(mH2) systems (with n = 1, 2, 4, 6, 8, 14 and m = 1, 2, 3, 4, with m the number of H2 for each Li) lies within a range of 0.13–0.20 eV/H2 which is compatible to the required range for adsorption/desorption of H2-molecules at room conditions. A H2-storage gravimetric capacity up to 4.63% was found for 14Li@BPNT(4H2) system. In addition, AIMD simulation strongly indicates that given adequate monitoring of the temperature, the charge/release process of H2-molecules can be controlled. Our findings suggest that Li-functionalized (7,7) boron phosphide nanotubes can provide a valuable underlying material for H2-storage technologies and therefore must certainly be the subject of further experimental exploration.

A Novel Carbon Support: Few‐Layered Graphdiyne‐Decorated Carbon Nanotubes Capture Metal Clusters as Effective Metal‐Supported Catalysts

Carbon-supported metal nanocatalysts have received substantial attention for heterogeneous catalysis in industry. Hunting for suitable and impactful carbon supports that have strong interactions with metal nanocatalyst is a matter of great urgency. Herein, a well-designed graphdiyne layer decorated on the carbon nanotubes sidewalls (CNT@GDY) serves as a novel carbon support. This unique hybrid structure effectively traps platinum and palladium atomic clusters (Pt/Pd-ACs) with dimensions of 0.65nm and 1.05nm uniformly and firmly, forming novel carbon-supported metal nanocatalysts (Pt(Pd)-ACs/CNT @ GDY) for efficient hydrogen generation and aromatic nitroreduction, respectively. The Pt-ACs/CNT@GDY can deliver an HER current density of 10mA cm-2 with a small overpotential of 23mV in 0.5 M H2 SO4 , showing a greatly enhanced mass activity, intrinsic activity than the commercial Pt/C catalyst. The Pd-ACs/CNT@GDY also exhibits excellent catalytic activity and a high turnover frequency of 38.0 min-1 for aromatic nitroreduction. The carbon support turns out to possess excellent conductivity, abundant and uniform reactive sites, low redox potential, more negative surface and large specific surface area as well as a strong interaction with ACs, as anticipated in ideal supports, which can be applied in other metal-supported catalysts.

Chemical functionalization of few walled carbon nanotubes produced by chemical vapour deposition technique

Materials with well-defined structures in the nanometer scale exhibit unique mechanical, optical and magnetic properties due to size related effects. Among the various nanomaterials studied, carbon nanotubes (CNTs) have great interest in several applications. The field of nanoscience and technology is an interdisciplinary field drawing researchers across materials science, technology and engineering disciplines each trying to exploit the advantages of this emerging field. The functionalized carbon nanotubes by acid-treatment were to afford dispensability in aqueous solution. The oxidized functional carboxyl groups which links the protein either covalently or non-covalently to the nanotubes sidewalls. Chemically functionalized few walled carbon nanotubes (FWCNTs) have promising effect in drug target and exhibit biocompatibility, excretion and less toxicity. CNTs were synthesised by chemical vapour deposition (CVD) method were FeMoMgO used as catalytic template. The purified CNTs were functionalised and it was characterised by FT-IR, SEM, HRTEM and Raman spectroscopy.