Outer Nanotube Research Articles

Structure-preserving analysis on chaotic characteristics of transverse vibration for embedded double-walled carbon nanotube

Abstract Analysing on the ultra-high frequency vibrational characteristics of carbon nanotubes, especially on the chaotic characteristics, is a key scientific problem in the dynamic design of the carbon nanotube devices. Considering the van der Waals force between the inner layer and the outer layer of the embedded double-walled carbon nanotube, and the effects of the elastic medium as well as the effects of the simple harmonic external excitation, the coupling dybamic model describing the transverse vibration of the embedded double-walled carbon nanotube is presented. The generalized multi-symplectic formulations with an explicit multi-symplectic structure residual are deduced by introducing the dual momenta. The Preissmann approach, which has been proved to be a structure-preserving method that can be used to reproduce the chaotic characteristics of carbon nanotubes, is employed to discrete the generalized multi-symplectic formulations. The numerical results imply that, the transverse vibration of the embedded double-walled carbon nanotube subjected to the external excitation larger than the critical external excitation will enter the chaotic state through a period-doubling bifurcation path. In addition, the critical external excitation for the chaos of the inner layer carbon nanotube’s transverse vibration is larger than that of the outer layer carbon nanotube’s transverse vibration. The above findings reported in this paper provide some guidance for the dynamic design of the carbon nanotube devices directly.

One-Dimensional van der Waals Heterojunction Comprising Carbon Nanotube Half-Wrapped in Boron Nitride Nanotube: Deep Investigation of Thermal Rectification.

One-dimensional van der Waals (vdWs) heterostructures are celebrated for their exceptional thermal management capabilities, garnering significant research interest. Consequently, our research focused on the one-dimensional vdWs heterojunction comprising carbon nanotube half-wrapped in boron nitride nanotube (BNCNT), specifically their thermal rectification (TR) properties. We employed non-equilibrium molecular dynamics to explore the TR mechanism and assess the impacts of temperature, strain, and coupling strength on heat flux and TR ratio. Our findings reveal that the backward heat flux demonstrates greater atomic vibration instability, as indicated by mean square displacement (MSD), compared to forward heat flux. This instability leads to a higher concentration of localized phonons, thereby diminishing the backward heat flux and enhancing TR. Additionally, we utilized MSD to shed light on the negative differential thermal resistance phenomenon and the influence of stress on forward and backward heat fluxes. Remarkably, TR ratios reached 344% at 3% strain and 400% at -1% strain. Calculations of phonon density of states revealed a competitive mechanism between in-plane and out-of-plane phonons coupling in the inner carbon nanotube and an overlap degree of out-of-plane phonon spectra between the inner carbon nanotube and outer boron nitride nanotube. This accounts for the differing trends in forward and backward heat fluxes as coupling strength χ increases, with TR ratios exceeding 1000% at χ = 7.5. This study provides vital insights for advancing one-dimensional vdWs thermal rectifiers.

Dynamics and Stability of Double-Walled Carbon Nanotube Cantilevers Conveying Fluid in an Elastic Medium

The paper concerns the dynamics and stability of double-walled carbon nanotubes conveying fluid. The equations of motion adopted in the current study to describe the dynamics of such nano-pipes stem from the classical Bernoulli–Euler beam theory. Several additional terms are included in the basic equations in order to take into account the influence of the conveyed fluid, the impact of the surrounding medium and the effect of the van der Waals interaction between the inner and outer single-walled carbon nanotubes constituting a double-walled one. In the present work, the flow-induced vibrations of the considered nano-pipes are studied for different values of the length of the pipe, its inner radius, the characteristics of the ambient medium and the velocity of the fluid flow, which is assumed to be constant. The critical fluid flow velocities are obtained at which such a cantilevered double-walled carbon nanotube embedded in an elastic medium loses stability.

Enhancing the cycling stability of commercial silicon nanoparticles by carbon coating and thin layered single-walled carbon nanotube webbing

Silicon-based anode materials are considered as the most attractive alternatives to traditional graphite anodes, thereby advancing the evolution of new-generation lithium-ion battery technology. However, the inadequate electrical conduction of silicon-based materials, along with severe volume expansion during charging and discharging processes, limits their further technological applications. Herein, a dual-layer carbon shell configuration is designed to efficiently alleviate the substantial volumetric expansion of silicon during cycles, while simultaneously improving the efficiency of both electron and lithium ions. The effectiveness of this layered buffering approach is credited to the networked structure of outer single-walled carbon nanotubes (SWCNTs) layer, which is firmly attached to the inner carbon shell's surface. The modified structure not only elevates the level of electrical conduction, but also significantly reduces the internal stress due to silicon's expansion. The developed Si@C@SWCNT electrode materials exhibit high capacity of 1267.3 mA h g−1 after 500 cycles at 1 A g−1, and sustains an elevated rate capacity of 863 mA h g−1 at 8 A g−1. This study highlights the enormous potential of Si@C@SWCNT composites for use in lithium-ion batteries and provides new perspectives for further exploration and utilization of silicon-carbon anodes.

Buckling behavior of ternary one-dimensional van der Waals heterostructures

One-dimensional van der Waals heterostructures (1D vdWHs) may suffer from external compression when applied in field-effect, light-emitting and photovoltaic devices. Ternary 1D vdWHs were recently reported to be successfully synthesized (Xiang et al 2020 Science 367, 537). In present work, the buckling behavior of ternary 1D vdWH consisting of an inner carbon nanotube, a middle boron nitride nanotube and an outer molybdenum disulfide nanotube is extensively investigated by using molecular dynamics simulations. We find that the composite can effectively enhance the capability of axial compression of the inner nanotubes. The 1D vdWH gradually loses its stability under uniaxial compression and the critical stress of buckling decreases as the temperature increases. Slenderness ratio α of 4.8 ≤ α ≤ 7.2 has a slight influence on the strength and stability of ternary 1D vdWH under axial compression. To obtain a 1D vdWH with best compressive stability and strength, there is an optimal diameter existing for any specific length. Our work provides guidance for the design of 1D vdWH with desired compressive stability.

Molecular simulation of modified large interstice outer wall carbon nanotube membrane and its desalination behavior

Large size interstices of carbon nanotube arrays have been proved to exhibit extremely higher water permeation. However, ion retention is still a big problem if the gap is to be used in desalination. Herein, nonequilibrium molecular dynamics simulations were applied to investigate water and ions transport among the different-size (9 Å, 11 Å, 13 Å, and 15 Å) interstices of outer wall membrane of the (10, 10) CNT array. Modifications were performed to improve salt rejection. The modifications included different lengths and types of carbon chains with hydrophilic COO– or NH3+. Simulation results revealed that 100% salt rejection can be achieved by using different functional groups for the outer wall CNT membrane with 9 Å, 11 Å, 13 Å and 97.24% for 15 Å interstices. Importantly, the water fluxes through the interstice (9 Å, 11 Å, 13 Å, and 15 Å) of the outer wall CNT membrane with high desalination were 3.43, 4.52, 5.95 and 5.49 times higher of than that of closely packed modified (10,10) CNT membrane with 100% desalination, respectively, implying the great potential of the interstice array of CNT as building blocks for the preparation of next-generation desalination membranes.

Carbon Nanotube Interwoven Polyhedrons with Inside-out Lithiophilic Gradients toward Stable Lithium Metal Battery

Lithium metal is one of the most potential anode materials for secondary batteries with high energy density. Nevertheless, the uncontrolled dendrite growth, fragile solid electrolyte interphase and theoretical infinite volume expansion during repeated plating/stripping process cause low Coulombic efficiency, short cycle life, and safety hazard. Carbon nanotube interwoven polyhedrons evolved from ZIF-8@ZIF-67 core–shell framework with inside-out lithiophilic gradients are prepared for lithium metal accommodation. The well-designed architecture with decreasing gradient of the main lithiophilic content ZnO from the inside out enables dendrite-free lithium deposition and stripping, and the outer interwoven carbon nanotubes induced by Co nanoparticles provide an optimal path to guide the diffusion of Li ion reduction from inside to outside as well as excellent electron conduction network for the whole anode. As the lithium metal host, the average Coulombic efficiency of lithium metal batteries can reach up to 98.2% (200 cycles) at 1 mA cm−2, and an extended lifespan (1500 h) is achieved at 3 mA cm−2. As was expected, outstanding capacity retention (82.7% after 300 cycles) with a competitive high-mass-loading (18.3 mg cm−2) LiFePO4 cathode at 1 C is realized. This structure design concept expands a promising application pathway of abundant carbon-based materials in lithium metal batteries.

Cryogenic TEM imaging of artificial light harvesting complexes outside equilibrium

The energy transport in natural light-harvesting complexes can be explored in laboratory conditions via self-assembled supramolecular structures. One such structure arises from the amphiphilic dye C8S3 molecules, which self-assemble in an aqueous medium to a double-wall cylindrical nanotube reminiscent of natural light-harvesting complexes found in green sulphur bacteria. In this paper, we report a way to investigate the structure of inner nanotubes (NTs) alone by dissolving the outer NTs in a microfluidic setting. The resulting thermodynamically unstable system was rapidly frozen, preventing the reassembly of the outer NT from the dissolved molecules, and imaged using cryogenic transmission electron microscopy (cryo-TEM). The experimental cryo-TEM images and the molecular structure were compared by simulating high-resolution TEM images, which were based on the molecular modelling of C8S3 NTs. We found that the inner NT with outer walls removed during the flash-dilution process had a similar size to the parent double-walled NTs. Moreover, no structural inhomogeneity was observed in the inner NT after flash-dilution. This opens up exciting possibilities for functionalisation of inner NTs before the reassembly of the outer NT occurs, which can be broadly extended to modify the intra-architecture of other self-assembled nanostructures.

Space-controllable TiO2@IrO2 core-shell nanotube array as a bio-interface electrode

This study develops a wet chemical approach to fabricate space-controllable TiO2@IrO2 core@shell nanotube arrays. The process begins with the space-controlling anodization of the TiO2 nanotube array, followed by a chemical bath deposition of IrO2. IrO2 uniformly covers the nanotubular TiO2 with a thickness range of 8– 15 nm. Charge storage capacity (CSC) and electrochemical impedance spectroscopy (EIS) are performed to evaluate the TiO2@IrO2 core-shell nanotube array as an electrode for neural activity application. Electron microscopy images confirm the formation of uniform IrO2 films on both inner and outer nanotube surfaces. An X-ray diffraction pattern shows a good crystallinity of the TiO2@IrO2 core-shell nanotube array. The TiO2@IrO2 core-shell nanotube array presents a large charge storage capacity of 42.84 mC/cm2 attributed to the high-aspect-ratio tubular nanostructure with a conformal IrO2 deposition. Additionally, the TiO2@IrO2 core-shell nanotube array exhibits stability, durability, and good biocompatibility.

Interlayer Interactions in 1D Van der Waals Moiré Superlattices.

Studying two‐dimensional (2D) van der Waals (vdW) moiré superlattices and their interlayer interactions have received surging attention after recent discoveries of many new phases of matter that are highly tunable. Different atomistic registry between layers forming the inner and outer nanotubes can also form one‐dimensional (1D) vdW moiré superlattices. In this review, experimental observations and theoretical perspectives related to interlayer interactions in 1D vdW moiré superlattices are summarized. The discussion focuses on double‐walled carbon nanotubes (DWNTs), a model 1D vdW moiré system, and the authors highlight the new optical features emerging from the non‐trivial strong interlayer coupling effect and the unique physics in 1D DWNTs. Future directions and questions in probing the intriguing physical phenomena in 1D vdW moiré superlattices such as, correlated physics in different 1D moiré systems beyond DWNTs are proposed and discussed.

The Identification of Cu-O-C Bond in Cu/MWCNTs Hybrid Nanocomposite by XPS and NEXAFS Spectroscopy.

The results of the research of a composite based on multi-walled carbon nanotubes (MWCNTs) decorated with CuO/Cu2O/Cu nanoparticles deposited by the cupric formate pyrolysis are discussed. The study used a complementary set of methods, including scanning and transmission electron microscopy, X-ray diffractometry, Raman, and ultrasoft X-ray spectroscopy. The investigation results show the good adhesion between the copper nanoparticles coating and the MWCNT surface through the oxygen atom bridge formation between the carbon atoms of the MWCNT outer graphene layer and the oxygen atoms of CuO and Cu2O oxides. The formation of the Cu–O–C bond between the coating layer and the outer nanotube surface is clearly confirmed by the results of the O 1s near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) of the Cu/MWCNTs nanocomposite. The XPS measurements were performed using a laboratory spectrometer with sample charge compensation, and the NEXAFS studies were carried out using the synchrotron radiation of the Russian–German dipole beamline at BESSY-II (Berlin, Germany) and the NanoPES station at the Kurchatov Center for Synchrotron Radiation and Nanotechnology (Moscow, Russia).

Optical absorption tunability and local electric field distribution of gold-dielectric-silver three-layered cylindrical nanotube* *Project supportedby the Programs for Anhui Provincial Natural Science Foundation, China (Grant Nos. 1808085MA20 and 1808085MA05), Excellent Young Talents in University of Anhui Province, China (Grant No. gxyq2017027), the Key Scientific Research Foundation of Anhui Provincial Education Department, China (Grant Nos. KJ2019A0564 and KJ2018A0366), the Key Research

The effects of inner nanowire radius, shell thickness, the dielectric functions of middle layer and surrounding medium on localized surface plasmon resonance (LSPR) of gold-dielectric-silver nanotube are studied based on the quasi-staticapproximation. Theoretical calculation results show that LSPR of gold-dielectric-silver nanotube and LSPR numbers can bewell optimized by adjusting its geometrical parameters. The longer wavelength of mode takes place a distinct red-shift with increasing the inner nanowire radius and the thickness of middle dielectric layer,while a blue-shift with increasing outer nanotube thickness. The physical mechanisms are explained based on the plasmon hybridization theory, induced charges and phase retardation. In addition, the effects of middle dielectric function and surrounding medium on LSPR, and the local electric field factor are also reported. Our study provides the potential appications of gold-dielectric-silver nanotube in biological tissues, sensor and related regions.

An Oligonucleotide Sensor with Parallel Electrical Pathways

Point-of-care sensors can combat the spread of infectious diseases and inform timely treatments. But in order to be used in this capacity, point-of-care sensors need to combine rapid detection speed with high sensitivity. Detection speed has traditionally been reduced by increasing the sensing surface area of the device, but this can increase noise and reduce sensitivity. In this work we align multiple tube-in-a-tube (Tube^2) nanostructures across a trench between two electrodes. Each Tube^2 consists of a semiconducting carbon nanotube nested within an outer nanotube densely functionalized with oligonucleotide probes. This device design provides a high surface area, while forcing the electrical current through distinct electrical pathways, allowing the binding events to be sensitively detected. Using this device architecture, we demonstrate the selective detection of Lyme disease oligonucleotide biomarkers in physiological ionic strength conditions on the order of seconds.

Slippage-inhibiting effect of interfacial cross-linking of nanotubes by defluorination on the mechanical properties of free-standing multi-walled carbon nanotube yarns: Comparison with individual multi-walled carbon nanotubes

Carbon nanotube yarns (CNTYs) spun only by twisting have a low mechanical strength due to the slippage of individual CNTs. This hinders the practical applications of CNTYs. Here, we studied the slippage-inhibiting effect of the interfacial cross-linking of the nanotubes by defluorination on the mechanical properties of free-standing MWCNTYs and compared with the fracture tensile strength of the individual defluorinated MWCNTs. The mechanical properties of defluorinated MWCNTYs increased with increasing annealing temperature, and MWCNTYs defluorinated at 800 °C under a pressure of 76 Pa (p-deF800-MWCNTYs) exhibited an average specific fracture strength of 0.69 N/tex and an average specific fracture stiffness of 103.2 N/tex, with high flexibility. As the fracture tensile strength of individual defluorinated MWCNTs was low, the high strength of the p-deF800-MWCNTYs was attributed to the cross-linking of the active carbon atoms in the outer nanotubes with those of the adjacent nanotubes through sp2C and sp3C bonds, which led to the transfer of load to the yarns. Thus, the results of our study highlight the importance of good balance between the defects of CNTs and cross-linking between CNTs.

Synthesis and formation mechanism of novel double-thick-walled silicon carbide nanotubes from multiwalled carbon nanotubes

In this study, double-thick-walled (DTW) silicon carbide (SiC) nanotubes, the walls of which comprise connected disordered polycrystalline nanograins, were successfully synthesized for the first time via the reaction of multiwalled carbon nanotubes (MWCNTs) with Si powder. DTW SiC nanotubes are expected to exhibit novel properties unlike other SiC nanomaterials, owing to their intriguing geometries. The DTW SiC nanotubes had a wall thickness exceeding 20 nm, regardless of the external diameter, as indicated by transmission electron microscopy results. The DTW SiC nanotubes with a spacing of above 30 nm between the outer and inner nanotubes exhibited perfect double-walled structures. The inner and outer nanotubes were not connected in any region. When all the carbon was transformed into SiC, the volume of carbon increased to 2.2 times the initial value. These results reveal that DTW SiC nanotubes with perfect structures cannot be synthesized without an MWCNT wall thickness of at least 50 nm. Several types of DTW SiC nanotubes with different morphologies, such as diameter, end structure, and distance between the inner and outer nanotubes, were synthesized. The morphology of DTW SiC nanotubes can be controlled by changing the wall thickness and/or diameter of the original MWCNTs and the reaction conditions.

3D NiCo-Layered double Hydroxide@Ni nanotube networks as integrated free-standing electrodes for nonenzymatic glucose sensing

Nickel cobalt layered double hydroxide (NiCo-LDH)-based materials have recently emerged as catalysts for important electrochemical applications. However, they frequently suffer from low electrical conductivity and agglomeration, which in turn impairs their performance. Herein, we present a catalyst design based on integrated, self-supported nickel nanotube networks (Ni-NTNWs) loaded with NiCo-LDH nanosheets, which represents a binder-free, hierarchically nanostructured electrode architecture combining continuous conduction paths and openly accessible macropores of low tortuosity with an ultrahigh density of active sites. Similar to macroscale metallic foams, the NTNWs serve as three-dimensionally interconnected, robust frameworks for the deposition of active material, but are structured in the submicron range. Our synthesis is solely based on scalable approaches, namely templating with commercial track-etched membranes, electroless plating, and electrodeposition. Morphological and compositional characterization proved the successful decoration of the inner and outer nanotube surfaces with a conformal NiCo-LDH layer. Ni-NTNW electrodes and hydroxide-decorated variants showed excellent performance in glucose sensing. The highest activity was achieved for the catalyst augmented with NiCo-LDH nanosheets, which surpassed the modification with pure Ni(OH)2. Despite its low thickness of 20 µm, the optimized catalyst layer provided an outstanding sensitivity of 4.6 mA mM−1 cm−2, a low detection limit of 0.2 µM, a fast response time of 5.3 s, high selectivity and stability, and two linear ranges covering four orders of magnitude, up to 2.5 mM analyte. As such, derivatized interconnected metal nano-networks represent a promising design paradigm for highly miniaturized yet effective catalyst electrodes and electrochemical sensors.

Alpha helical surfactant-like peptides self-assemble into pH-dependent nanostructures.

A designed surfactant-like peptide is shown, using a combination of cryogenic-transmission electron microscopy and small-angle X-ray scattering, to have remarkable pH-dependent self-assembly properties. Peptide Arg3-Leu12 (R3L12) forms a network of peptide nanotubes at pH 9 and below. These are associated with α-helical conformation in a "cross-α" nanotube structure, in which peptide dimers lie perpendicular to the nanotube axis, with arginine coated inner and outer nanotube walls. In contrast, this peptide forms decorated vesicular aggregates at higher pH values, close to the pKa of the arginine residues. These structures are associated with a loss of α-helical order as detected through X-ray scattering, circular dichroism and FTIR spectroscopy, the latter technique also revealing a loss of ordering of leucine side chains. This suggests a proposed model for the decorated or patchy vesicular structures that comprises disordered peptide as the matrix of the membrane, with small domains of ordered peptide dimers forming the minority domains. We ascribe this to a lipid-raft like phase separation process, due to conformational disordering of the leucine hydrophobic chains. The observation of the self-assembly of a simple surfactant-like peptide into these types of nanostructure is remarkable, and peptide R3L12 shows unique pH-dependent morphological and conformational behaviour, with the potential for a range of future applications.

Electronic structures and band alignment transition in double-wall MoS2/WS2 nanotubes for optoelectronic applications

Band alignment caused by discontinuous band structures of two different materials plays a central role in semiconductor heterojunctions and interface physics. We investigate the electronic structures and band alignments of double-wall MoS2/WS2 nanotubes with different chirality and geometry. We find that the band gap of both armchair and zigzag nanotubes obeys with being the band gap of the inner nanotube and the spacing distance between the inner and outer nanotubes. When placing MoS2 in the inner and WS2 in the outer of the nanotubes, the band alignment belongs to type-I because the conduction band minimum (CBM) of the inner MoS2 nanotube is lower than that of the outer WS2 nanotube, and the valence band maximum (VBM) of MoS2 nanotube is higher than that of WS2 nanotube. While putting the WS2 nanotube in the inner and MoS2 nanotube in the outer, the CBM and VBM of MoS2 nanotube are both lower than the corresponding band extreme points of WS2 nanotube when their diameter is small. Therefore, type-II to type-I band alignment transition occurs, originating from charge transfer with increasing spacing distance. Due to the adjustable band gap and electronic structures, we expect that these double-wall hetero-structured nanotubes will have great potential in optoelectronic devices.

Water distribution in confined space of single-wall carbon nanotube

Since the discovery of carbon nanotubes (CNTs), they have attracted extensive attention from scholars in various fields because of their excellent properties. The hollow-structured CNTs are often regarded as conduits and containers, which can act as nano-channels for various molecular substances in the membrane structure. As a source of life, water is indispensable to any living organism. In the application of carbon nanotubes as nanochannels, the most important is the ability of carbon nanotubes to store and transport liquids, especially nanoscaled aqueous solutions. Water molecular clusters in confined spaces exhibit unusual structures and properties. The study of special water structures in carbon nanotubes is of great theoretical importance in chemistry, biology and materials science. There are great difficulties in making the experiment on a nanoscale, but molecular dynamic simulation enables us to better study and analyze the structure and properties of water in confined space of CNT on a nanoscale. One has also studied the influence of temperature on the structure of water, but there are few studies focusing on the effect of temperature on the structure of water in confined space. Therefore, molecular dynamics simulation is used to investigate the effects of CNT diameter, CNT chirality and temperature on the water structure and distribution in a confined space. The simulation calculation is completed by GROMACS, the SPE/C water model is used for water molecules, and GROMOS96 54a7 force field is used. Because of the presence of carbon nanotubes, water molecules tend to line up against the walls of the tubes, both inside and outside. In addition, water molecules tend to form highly ordered multi-ring structures in the carbon nanotubes with a size of 1.018–1.253 nm at a certain temperature. It is difficult to form the ordered structure of water in the outer carbon nanotubes. In the above range, with the increase of pipe diameter, the structure of multi-element ring water changes from three-element ring to six-element ring. On the one hand, the ordered structure depends on the diameter of the carbon nanotube, but the chirality of the carbon nanotube does not have a great influence on it. On the other hand, the stability of the ordered structure is temperature-dependent, and the ordered structure of multiple ring water in the carbon nanotube with a larger diameter is more likely to disappear with the increase of temperature. The van der Waals potential distribution is calculated by Multiwfn, and it is concluded that the van der Waals potential inside the tube is extremely low, resulting in a very large dispersion effect, and molecules can spontaneously move from the outer area to the tube. The van der Waals potential can also be negative outside the tube. This explains why water molecules tend to line up against the wall of the tube.

Atomic Layer Deposition of SnO2-Coated Anodic One-Dimensional TiO2 Nanotube Layers for Low Concentration NO2 Sensing.

The continuous emission of nitrous oxides contributes to the overall air pollution and deterioration of air quality. In particular, an effective NO2 sensor capable of low concentration detection for continuous monitoring is demanded for safety, health, and wellbeing. The sensing performance of a metal oxide-based sensor is predominantly influenced by the availability of surface area for O2 adsorption and desorption, efficient charge transport, and size or thickness of the sensing layer. In this study, we utilized anodic one-dimensional (1D) TiO2 nanotube layers of 5 μm thick which offer large surface area and unidirectional electron transport pathway as a platform to accommodate thin SnO2 coatings as a sensing layer. Conformal and homogeneous SnO2 coatings across the entire inner and outer TiO2 nanotubes were achieved by atomic layer deposition with a controlled thickness of 4, 8, and 16 nm. The SnO2-coated TiO2 nanotube layers attained a higher sensing response than a reference Figaro SnO2 sensor. Specifically, the 8 nm SnO2-coated TiO2 nanotube layer has recorded up to ten-fold enhancement in response as compared to the blank nanotubes for the detection of 1 ppm NO2 at an operating temperature of 300 °C with 0.5 V applied bias. This is attributed to the SnO2/TiO2 heterojunction effect and controlled SnO2 thickness within the range of the Debye length. We demonstrated in this work, a tailored large surface area platform based on 1D nanotubes with thin active coatings as an efficient approach for sensing applications and beyond.