Crystalline Sheets Research Articles

Mesoscale modeling of deformations and defects in thin crystalline sheets

We present a mesoscale description of deformations and defects in thin, flexible sheets with crystalline order, tackling the interplay between in-plane elasticity, out-of-plane deformation, as well as dislocation nucleation and motion. Our approach is based on the Phase-Field Crystal (PFC) model, which describes the microscopic atomic density in crystals at diffusive timescales, naturally encoding elasticity and plasticity effects. In its amplitude expansion (APFC), a coarse-grained description of the mechanical properties of crystals is achieved. We introduce surface PFC and surface APFC models in a convenient height-function formulation encoding deformation in the normal direction. This framework is proven consistent with classical aspects of strain-induced buckling, defect nucleation on deformed surfaces, and out-of-plane relaxation near dislocations. In particular, we benchmark and discuss the results of numerical simulations by looking at the continuum limit for buckling under uniaxial compression and at evidence from microscopic models for deformation at defects and defect arrangements, demonstrating the scale-bridging capabilities of the proposed framework. Results concerning the interplay between lattice distortion at dislocations and out-of-plane deformation are also illustrated by looking at the annihilation of dislocation dipoles and systems hosting many dislocations. With the novel formulation proposed here, and its assessment with established approaches, we envision applications to multiscale investigations of crystalline order on deformable surfaces.

Liquid-Liquid Phase Separation Mediated Formation of Chiral 2D Crystalline Nanosheets of a Co-Assembled System.

The role of macromolecule-macromolecule and macromolecule-H2O interactions and the resulting perturbation of the H-bonded network of H2O in the liquid-liquid phase separation (LLPS) process of biopolymers are well-known. However, the potential of the hydrated state of supramolecular structures (non-covalent analogs of macromolecules) of synthetic molecules is not widely recognized for playing a similar role in the LLPS process. Herein, LLPS occurred during the co-assembly of hydrated supramolecular vesicles (bolaamphiphile, BA1) with a net positive charge (zeta potential, ζ = +60 ± 2mV) and a dianionic chiral molecule (disodium l-[+]-tartrate) is reported. As inferred from cryo-transmission electron microscopy (TEM), the LLPS-formed droplets serve as the nucleation precursors, dictating the structure and properties of the co-assembly. The co-assembled structure formed by LLPS effectively integrates the counter anion's asymmetry, resulting in the formation of ultrathin free-standing, chiral 2D crystalline sheets. The significance of the hydrated state of supramolecular structures in influencing LLPS is unraveled through studies extended to a less hydrated supramolecular structure of a comparable system (BA2). The role of LLPS in modulating the hydrophobic interaction in water paves the way for the creation of advanced functional materials in an aqueous environment.

Influence of Peptoid Sequence on the Mechanisms and Kinetics of 2D Assembly.

Two-dimensional (2D) materials have attracted intense interest due to their potential for applications in fields ranging from chemical sensing to catalysis, energy storage, and biomedicine. Recently, peptoids, a class of biomimetic sequence-defined polymers, have been found to self-assemble into 2D crystalline sheets that exhibit unusual properties, such as high chemical stability and the ability to self-repair. The structure of a peptoid is close to that of a peptide except that the side chains are appended to the amide nitrogen rather than the α carbon. In this study, we investigated the effect of peptoid sequence on the mechanism and kinetics of 2D assembly on mica surfaces using in situ AFM and time-resolved X-ray scattering. We explored three distinct peptoid sequences that are amphiphilic in nature with hydrophobic and hydrophilic blocks and are known to self-assemble into 2D sheets. The results show that their assembly on mica starts with deposition of aggregates that spread to establish 2D islands, which then grow by attachment of peptoids, either monomers or unresolvable small oligomers, following well-known laws of crystal step advancement. Extraction of the solubility and kinetic coefficient from the dependence of the growth rate on peptoid concentration reveals striking differences between the sequences. The sequence with the slowest growth rate in bulk and with the highest solubility shows almost no detachment; i.e., once a growth unit attaches to the island edge, there is almost no probability of detaching. Furthermore, a peptoid sequence with a hydrophobic tail conjugated to the final carboxyl residue in the hydrophilic block has enhanced hydrophobic interactions and exhibits rapid assembly both in the bulk and on mica. These assembly outcomes suggest that, while the π-π interactions between adjacent hydrophobic blocks play a major role in peptoid assembly, sequence details, particularly the location of charged groups, as well as interaction with the underlying substrate can significantly alter the thermodynamic stability and assembly kinetics.

Surface-Guided Crystallization of Xanthine Derivatives for Optical Metamaterial Applications.

Numerous bio-organisms employ template-assisted crystallization of molecular solids to yield crystal morphologies with unique optical properties that are difficult to reproduce synthetically. Here, a facile procedure is presented to deposit bio-inspired birefringent crystals of xanthine derivatives on a template of single-crystal quartz. Crystalline sheets that are several millimeters in length, several hundred micrometers in width, and 300-600nm thick, are obtained. The crystal sheets are characterized with a well-defined orientation both in and out of the substrate plane, giving rise to high optical anisotropy in the plane parallel to the quartz surface, with a refractive index difference Δn ≈ 0.25 and a refractive index along the slow axis of n ≈ 1.7. It is further shown that patterning of the crystalline stripes with a tailored periodic grating leads to a thin organic polarization-dependent diffractive meta-surface, opening the door to the fabrication of various optical devices from a platform of small-molecule based organic dielectric crystals.

Subtle Molecular Changes Largely Modulate Chiral Helical Assemblies of Achiral Conjugated Polymers by Tuning Solution-State Aggregation.

Understanding the solution-state aggregate structure and the consequent hierarchical assembly of conjugated polymers is crucial for controlling multiscale morphologies during solid thin-film deposition and the resultant electronic properties. However, it remains challenging to comprehend detailed solution aggregate structures of conjugated polymers, let alone their chiral assembly due to the complex aggregation behavior. Herein, we present solution-state aggregate structures and their impact on hierarchical chiral helical assembly using an achiral diketopyrrolopyrrole-quaterthiophene (DPP-T4) copolymer and its two close structural analogues wherein the bithiophene is functionalized with methyl groups (DPP-T2M2) or fluorine atoms (DPP-T2F2). Combining in-depth small-angle X-ray scattering analysis with various microscopic solution imaging techniques, we find distinct aggregate in each DPP solution: (i) semicrystalline 1D fiber aggregates of DPP-T2F2 with a strongly bound internal structure, (ii) semicrystalline 1D fiber aggregates of DPP-T2M2 with a weakly bound internal structure, and (iii) highly crystalline 2D sheet aggregates of DPP-T4. These nanoscopic aggregates develop into lyotropic chiral helical liquid crystal (LC) mesophases at high solution concentrations. Intriguingly, the dimensionality of solution aggregates largely modulates hierarchical chiral helical pitches across nanoscopic to micrometer scales, with the more rigid 2D sheet aggregate of DPP-T4 creating much larger pitch length than the more flexible 1D fiber aggregates. Combining relatively small helical pitch with long-range order, the striped twist-bent mesophase of DPP-T2F2 composed of highly ordered, more rigid 1D fiber aggregate exhibits an anisotropic dissymmetry factor (g-factor) as high as 0.09. This study can be a prominent addition to our knowledge on a solution-state hierarchical assembly of conjugated polymers and, in particular, chiral helical assembly of achiral organic semiconductors that can catalyze an emerging field of chiral (opto)electronics.

Deep electrical resistivity imaging of crustal structures along the Satluj River valley, northwest Himalaya, India

Magnetotelluric (MT) investigations along the Nahan- Kourick Chango transect in the Satluj river valley, northwest Himalayas, provide insight into the subsurface electrical properties. In the geoelectrical model, medium to highly metamorphosed crystalline rocks in the Lesser and the Higher Himalayas are observed as high resistive features. At a depth approximately 5–15 km, an intra-crustal low resistive layer is consistently present along the entire profile. The geometry of this dipping intra-crustal layer signifies the presence of the Main Himalayan Thrust, which represents the base of the accretionary wedge where all the major thrusts of the Himalayan tectonics sole down. The geometrical differences and distinct resistivity of this layer compared to the adjacent regions of Garhwal-Kumaon and Nepal Himalaya indicate the variability of tectonic processes in this part of the Himalaya. Another significant observation is the existence of a thin, highly conducting layer at a shallow depth (approximately 1–3 km). The spatial extent of this layer, along with the bending extent of the main central thrust toward the south, suggests its role in the southward translation of crystalline sheets during Himalayan tectonics.

Synthesis of well-defined ester-linked covalent organic polymer and its potential applications in C–H bond activation

Among all polymeric materials, the chemistry of covalent organic polymers has been the least covered in the field of photocatalysis due to the rare availability of design and synthetic protocols. In the present work, we have come up with an efficient design of a one-dimensional Covalent Organic polymer (COP) (S-COP) through the ester-linked co-polymerization of Erythrosine B with 2,2′-Dithiodibenzoic acid (2,2′-DDB). The COP was synthesized via the facile one-pot solvothermal method. The XRD data analysis favors high crystalline nanoscale polymeric sheet generation (S-COP, 90.5 % & 43.5 nm). The HOMO-LUMO calculation through an electrochemical study as well as Tauc's plot showed 2.1 eV band gap. In this order, S-COP, a metal-free polymeric material was observed as an effective photocatalyst in the solar-driven photocatalytic reaction of heteroarenes with aryl diazonium salts via direct C-H arylation (High yield (∼98 %), and high selectivity (∼98 %)).

Tandem catalysts of different crystalline In2O3/sheet HZSM-5 zeolite for CO2 hydrogenation to aromatics

In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as “the closer, the better”. However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In2O3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO2 by oxygen vacancy on c-In2O3(111) and h-In2O3(104) planes, it was found that Ov1 on c-In2O3(111) and Ov4 on h-In2O3(104) had the strongest adsorption energy for CO2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO2 conversion and aromatic selectivity are decreased.

Molecule-induced n-type behavior of phosphorene-based field-effect transistor for highly sensitive detection of sialic acid

Low-concentration detection of sialic acid (SA) seems to be a promising method in early cancer prognosis. In this work, a phosphorene-based field-effect-transistor (Ph-FET) device has been introduced for detecting various concentrations of SA. The device was fabricated using successive hydrogen plasma treatment to start from the red phosphorus layer and to realize highly crystalline black phosphorus sheets. The morphology and crystalline quality of phosphorene sheets have been extensively examined by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. By utilizing this device, we can detect different concentrations of SA from 3 to 2400 μM owing to its negative charge. The detection limit of SA is as low as 2.8 μM. This technique offers a straightforward method for the fabrication of high-performance Ph-FET with no need for exfoliation or sheet transfer. We have fabricated a Ph-FET with a mobility of 10 cm2 V−1 s−1, a carrier concentration of 3.9 × 1011 cm−2, and an on/off current ratio of 103. Moreover, we have observed that exposure to SA solution would change the carrier type of the transistor from a p-type channel into an n-type channel device due to the interaction of SA molecules with the phosphorene atoms at the top of the puckered structure that weakens the P-P lattice anti-bonding orbitals and screens the trapped sites.

Scalable synthesis of ultrathin MoS2 membranes for dye desalination

Molybdenum disulfide (MoS2) has been fabricated into thin-film composite (TFC) membranes for dye desalination due to its excellent underwater stability and tunable interlay spacing. However, it remains challenging to synthesize thin layers of MoS2 with high water permeance and high dye rejection due to the difficulty in fabricating large crystalline sheets or exfoliation. Herein, we report a scalable method coupling bottom-up hydrothermal synthesis and top-down ultrasonic exfoliation to obtain well-dispersed MoS2 nanosheets and a vacuum filtration method to prepare ultrathin membranes (thickness: 30 – 60 nm) for dye desalination. The MoS2 nanosheets and membranes are thoroughly characterized for their chemistries and nanostructures. The membrane with 60-nm MoS2 exhibits water permeance of 32 LMH/bar, Na2SO4 rejection of 2.3%, and Direct Red-80 rejection of 99.0%. The MoS2 membranes exhibit dye desalination performance superior to state-of-the-art commercial polyamide membranes and many leading membranes based on two-dimensional materials.

Regulation of multi-scale structures and retrogradation property of A- and B-type wheat starch granules with maltogenic α-amylase

Maltogenic α-amylase (MA) is widely used to modify starch for improving properties. In this work, A- and B-type starches were separated from wheat completely and submitted to MA hydrolysis. Firstly, research in morphological features (SEM) suggested that MA treatment did not destroy the granule integrity. Next, crystalline features from XRD and SAXS assay showed that MA treatment did not change the crystal form, but deceased crystalline sheet (dc) and amorphous sheet (da) thickness in both modified starches. And amorphous sheet was more severely destroyed at higher MA dosage than crystalline sheet. Then changes in molecule structure (HPAEC) showed that MA mainly acted on sides chains with degree of polymerization 12–24 in amylopectin for both starches, resulting in a reduce in peak, trough, and final viscosity obtained from RVA assay. At last, RVA and DSC assay showed that the short-term and long-term retrogradation were retarded in both modified starches. This range of techniques covered changes in multi-scale structures and retrogradation property resulted from MA treatment on both starches, which provided references for studying the changes in structures and properties of MA modified starch granules and provided an important method for retarding retrogradation of starchy foods without gelatinization processing.

A monolayer crystalline covalent network of polyoxometalate clusters

Monolayer two-dimensional (2D) materials are of great interest because of their unique electronic structures, noticeable in-plane confinement effect, and exceptional catalytic properties. Here, we prepared 2D covalent networks of polyoxometalate clusters (CN-POM) featuring monolayer crystalline molecular sheets, formed by the covalent connection between tetragonally arranged POM clusters. The CN-POM shows a superior catalytic efficiency in the oxidation of benzyl alcohol, and the conversion rate is five times higher than that of the POM cluster units. Theoretical calculations show that in-plane electron delocalization of CN-POM contributes to easier electron transfer and increases catalytic efficiency. Moreover, the conductivity of the covalently interconnected molecular sheets was 46 times greater than that of individual POM clusters. The preparation of monolayer covalent network of POM clusters provides a strategy to synthesize advanced cluster-based 2D materials and a precise molecular model to investigate the electronic structure of crystalline covalent networks.

Ultrathin Crystalline Silicon Nano and Micro Membranes with High Areal Density for Low-Cost Flexible Electronics.

Ultrathin crystalline silicon is widely used as an active material for high-performance, flexible, and stretchable electronics, from simple passive and active components to complex integrated circuits, due to its excellent electrical and mechanical properties. However, in contrast to conventional silicon wafer-based devices, ultrathin crystalline silicon-based electronics require an expensive and rather complicated fabrication process. Although silicon-on-insulator (SOI) wafers are commonly used to obtain a single layer of crystalline silicon, they are costly and difficult to process. Therefore, as an alternative to SOI wafers-based thin layers, here, a simple transfer method is proposed for printing ultrathin multiple crystalline silicon sheets with thicknesses between 300nm to 13µm and high areal density (>90%) from a single mother wafer. Theoretically, the silicon nano/micro membrane can be generated until the mother wafer is completely consumed. In addition, the electronic applications of silicon membranes are successfully demonstrated through the fabrication of a flexible solar cell and flexible NMOS transistor arrays.

Synthesis and Crystal Structure of a New RTH-Type Precursor and Its Interlayer Expanded Zeolite.

Two dimensional zeolites have drawn a lot of attention due to their structural diversity and chemical composition, which can be used to obtain 3D zeolites, for which there is no direct synthesis. Here, a new layer silicate zeolite L was synthesized using the N, N-dimethyl-(2-methyl)-benzimidazolium as the organic structure-directing agent (OSDA) in the presence of fluoride. Structure determination by single-crystal X-ray diffraction reveals that the pure silica precursor with five-ring pores in the crystalline sheets is composed of the rth layer stacking along the (001) direction in an …AAAA… sequence with SDA+ cations and F- residing within the interlayer spaces. Variable temperature powder X-ray diffraction (PXRD) results showed that the new layer could transform into a 3D RTH topology structure at 350 °C via 2D-3D topotactic transformation. Furthermore, a new 3D zeolite material is obtained by treating the original layer with a diethoxydimethylsilane agent under hydrochloric acid condition (HCl-DEDMS). Based on the PXRD results and the original layer structure, the new 3D zeolite structure expanding the rth layer with another Si atom is constructed, which possesses a 10×8×6 channel system. It displays a high BET surface area of 188 cm3 /g with an external surface area of 130 cm3 /g. The structure and textural properties pave a way for potential catalytic applications. The research not only provides a new layered zeolite, broadening the 2D zeolite framework types, but also allows for the discovery of a new stable 3D zeolite expanding the RTH structure with Si atom, which hasn't been reported yet.

Spatially restricted strategy to construct crystalline carbon nitride nanosheet assists exciton dissociation to enhance photocatalytic hydrogen evolution activity

Two-dimensional carbon nitride nanosheets continue to attract attention in photocatalysis, but inefficient exciton dissociation and charge separation limit further improvement of their photocatalytic performance. Herein, we have prepared highly crystalline carbon nitride sheets using a integrated strategy of spatially restricted growth in solid salt media and hydrochloric acid induced exfoliation. In the confined space of the solid salt, K+ induce the ordered growth of carbon nitride and diffuse into the carbon nitride bulk phase with thermodynamically feasible paths. Pickling was also found to control the K+ concentration gradient distribution and regulate the charge characteristic of cyanoamino, thereby controlling the quantity and activity of trapped long-lived electrons. The storage free electron behavior of carbon nitride dual-functionalized with cyanoamino and K+ (KCCN) greatly facilitates the dissociation of excitons, resulting in photocatalytic hydrogen evolution efficiency of 10.78 mmol·g−1·h−1, which was 49 times higher than that of ordinary carbon nitride. KCCN had a hydrogen production quantum efficiency of 27.79%, higher than the majority of the similar materials reported. This study provides new insights into the design of more excellent carbon nitride-based photocatalysts through exciton engineering.

Eco-Friendly Synthesis of Wrinkle-Free Ultra-Flat Multi-Layer Graphene by Femtosecond Laser Irradiation of Graphite Under Ambient Conditions

Here, we report a single-step, high-yield technique for producing planar sheets of wrinkle-free multi-layer graphene (MLG) under ambient conditions by ablation of graphite powder dispersed in ethanol using a femtosecond laser. The parameters for the synthesis of MLG have been optimized and established. The number of layers and quality of MLG produced at several laser fluences (39.4 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 98.72 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 197.45 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 296.16 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) was established based on detailed characterization using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Wrinkle-free, ultra-flat crystalline MLG sheets with 2-12 layers were produced in each case with an average lateral dimension of ∼1-3 μm. The associated oxy- functional groups were characterized and quantified using FTIR and XPS. The highest percentage of sp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> C atoms and C/O ratio for MLG was achievedat the lowest laser fluence. The higher the laser fluence higher the defects produced in the MLG sheets. The technique produces zero chemical waste, has a very high yield of ∼ 95%, and is promising for bulk-scale production of MLG.

Ferroelectric Ionic Molecular Crystals with Significant Plasticity and a Low Melting Point: High Performance in Hot‐Pressed Polycrystalline Plates and Melt‐Grown Crystalline Sheets

AbstractAmong ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by press‐forming or by melt‐growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small‐molecule‐based ferroelectrics. Owing to the ready availability of large‐scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.

Ferroelectric Ionic Molecular Crystals with Significant Plasticity and a Low Melting Point: High Performance in Hot-Pressed Polycrystalline Plates and Melt-Grown Crystalline Sheets.

Among ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by press-forming or by melt-growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small-molecule-based ferroelectrics. Owing to the ready availability of large-scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.

Observation of formation and local structures of metal-organic layers via complementary electron microscopy techniques

Metal-organic layers (MOLs) are highly attractive for application in catalysis, separation, sensing and biomedicine, owing to their tunable framework structure. However, it is challenging to obtain comprehensive information about the formation and local structures of MOLs using standard electron microscopy methods due to serious damage under electron beam irradiation. Here, we investigate the growth processes and local structures of MOLs utilizing a combination of liquid-phase transmission electron microscopy, cryogenic electron microscopy and electron ptychography. Our results show a multistep formation process, where precursor clusters first form in solution, then they are complexed with ligands to form non-crystalline solids, followed by the arrangement of the cluster-ligand complex into crystalline sheets, with additional possible growth by the addition of clusters to surface edges. Moreover, high-resolution imaging allows us to identify missing clusters, dislocations, loop and flat surface terminations and ligand connectors in the MOLs. Our observations provide insights into controllable MOL crystal morphology, defect engineering, and surface modification, thus assisting novel MOL design and synthesis.

Localized Liquid Zones Assisted Highly Crystalline Single-Wall Carbon Nanotube Sheets: Implications for Conducting Shields in Coaxial Cables

The electrical conductivity of carbon nanotube (CNT) macro assemblies can be influenced by their crystallinity. Herein, we present the synthesis of high-quality SWCNT sheets for which an appropriate optimization parametric research of synthesis temperature, precursor flow rate, and H2 flow rate was carried out in this approach. It was found that highly crystalline SWCNT sheet (IG/ID = 180.3) was synthesized by floating catalyst chemical vapor deposition technique at 12 mL/h precursor flow rate and 1000 sccm H2 flow rate. Three distinct Raman laser wavelengths (514, 532, and 785 nm) were used to study the as-synthesized sheet, and the maximum calculated IG/ID ratio was found to be 180.3 (@ λ = 514 nm). Due to high concentration of H2 gas, the number of localized liquid zones or CNT nucleation sites increased which has an impact on both the quality as well as the diameter of CNTs. The I–V characteristics of CNT sheet were studied via four-probe technique, yielding a measured value of electrical conductivity of 9.21 × 106 S/m. Further, the R-T measurement showed the positive temperature coefficient up to the 108 K which indicates the metallicity of as produced CNT sheets. These highly conducting SWCNT sheets are the best solution for a wide range of applications in many fields, including conducting shields in coaxial cables, flexible and nano scale electrical and electronic devices, displays, biosensors, field-effect transistors and gas sensing materials.