Scrolling Process Research Articles

Effective remediation of toxic metal ions (Cd(II), Pb(II), Hg(II), and Ba(II)) using mesoporous glauconite-based iron silicate nanorods: Experimental and theoretical studies

Glauconite minerals underwent an advanced exfoliation and scrolling process, yielding novel iron silicate nanorods (GRs) with increased surface area, reactivity, and improved physicochemical properties. These structures were introduced as superior adsorbents for the highly efficient adsorption of various toxic metal ions, such as Cd(II), Pb(II), Hg(II), and Ba(II). The GRs exhibited maximum adsorption capacities of 283 mg/g for Cd(II), 247 mg/g for Pb(II), 132.3 mg/g for Hg(II), and 165.2 mg/g for Ba(II). The adsorption properties of the GRs during the adsorption of these four metal ions were elucidated through traditional (Langmuir model) and advanced (monolayer model of single energy site) isotherm analyses. Advanced isotherm modeling revealed that the GR surface was saturated with numerous effective adsorption sites, with densities of 125 mg/g for Cd(II), 68.8 mg/g for Pb(II), 40.9 mg/g for Hg(II), and 57.9 mg/g for Ba(II). Moreover, each site could accommodate approximately four ions of the studied metals, which are vertically oriented and participate in multi-ionic adsorption reactions. Energetic analyses, whether based on classical models (Gaussian energy <8 kJ/mol) or advanced models (adsorption energy <40 kJ/mol), indicated that the adsorption processes are governed by physical mechanisms, including electrostatic attractions, van der Waals forces, and hydrogen bonding. Furthermore, thermodynamic assessments confirmed that the adsorption of these ions occurs through exothermic and spontaneous reactions.

Real-Time Monitoring of Adsorption-Induced Scrolling of Colloidal Inorganic Nanosheets.

Inorganic nanotubes have attracted much attention due to their unique physicochemical properties. Nanotubes can be prepared by scrolling exfoliated nanosheets under ambient conditions. However, how the nanosheet scrolled in its colloidal state has not been experimentally visualized. In this paper, we directly observed the scrolling process of nanosheets upon adsorption of organic cations. Exfoliated flat nanosheets of niobate and clay in aqueous colloids were found to scroll by adding organic cations, such as exfoliation reagents, to the colloids. Employment of cationic stilbazolium dye enabled in situ observation of the dye adsorption and scrolling by optical microscopy based on changes in color and morphology of the nanosheets. The scrolling was promoted for nanosheets adsorbed with a stilbazolium dye with a longer alkyl chain, suggesting that the interaction between the hydrophobic parts of the dye cations is the driving force of the scrolling. This finding should encourage research on the formation of nanotubes from nanosheets and also provides important guidelines for the selection of appropriate exfoliation reagents when exfoliating nanosheets from layered crystals.

A facile and scalable fabrication method of scrolled graphene/boron nitride-based van der Waals superlattice heterostructure materials for highly stable supercapacitor electrode application.

Due to the increasing demand for the development of efficient renewable energy supply systems to reduce the mismatch between energy demand and utilization, supercapacitors have attracted increasing attention in the energy industry. However, the development of energy storage electrode materials to be applied at the industrial level is still challenging due to the unsatisfactory durability and scalable production issues. This study suggested a facile and scalable one-pot fabrication method of using graphene/hexagonal boron nitride (G/BN)-based one-dimensional (1D) van der Waals superlattice heterostructures (vdWSLs) as highly stable electrode materials to enhance the energy storage performance by improving the mesopore volume content, specific surface area, electrical properties, and interfacial interaction between the stacked G/BN layers. The G/BN-based vdWSLs were fabricated by a simple scrolling process through the electromagnetic interaction between the attached magnetic iron oxide nanoparticles (Fe3O4 NPs) on the surface of a G/BN vdW heterostructure (vdWH) and the applied magnetic field. The investigation results demonstrate that the changed morphology of the fabricated G/Fe/BN(NS) strongly affects the fine pore distribution, electrochemical performance, and electrical properties. Consequently, as a synergistic effect of an increased mesopore volume content, specific surface area, and C-B-N heterojunction interfacial area, the fabricated G/Fe/BN(NS) electrode showed a 100% enhancement of specific capacitance (207 F g-1 at 0.5 A g-1) and almost 7 times enhancement of electrical conductivity (800 S cm-1) with a nearly 2.3 times increase of carrier mobility (716 cm2 V-1 s-1) compared to that of the G/Fe/BN electrode. Furthermore, it exhibited outstanding long-term cycling stability with almost 119% capacitance retention even after 100 000 charge-discharge cycles. These results suggest that G/Fe/BN(NS) has tremendous potential as an electrode to fabricate high-performance supercapacitors with excellent cycling stability.

Synthesis and Characterization of Iron-Rich Glauconite Nanorods by a Facile Sonochemical Method for Instantaneous and Eco-friendly Elimination of Malachite Green Dye from Aquatic Environments.

Novel glauconite nanorods (GNRs) were synthesized by the sonication-induced chemical expansion and scrolling process of natural glauconite. The synthetic nanostructure was characterized by different analytical techniques as a superior adsorbent for the malachite green dye (MG). The synthetic GNRs were detected as porous nanorods with an average length of 150 nm to 5 μm, an average diameter of 25 to 200 nm, and a specific surface area of 123.7 m2/g. As an adsorbent for MG, the synthetic GNRs showed superior uptake capacity up to 1265.6 mg/g at the saturation stage, which is higher than most of the recently developed highly adsorbent dyes. The adsorption behavior and mechanistic properties were depicted by using modern and traditional equilibrium modeling. The kinetic assumption of the pseudo-first-order model (R2 > 0.94) and the classic isotherm of the Langmuir equilibrium model (R2 > 0.97) were used to describe the adsorption reactions. The steric investigation demonstrates that each active site on the surface of GNRs can adsorb up to three MG molecules (n = 2.19-2.48) in vertical orientation involving multimolecular mechanisms. Also, the determined active site density (577.89 mg/g) demonstrates the enrichment of the surface of GNRs with numerous adsorption receptors with strong affinity for the MG dye. The energetic study, including Gaussian energy (6.27-7.97 kJ/mol) and adsorption energy (9.45-10.43 kJ/mol), revealed that GNRs had physically adsorbed the dye, which might involve electrostatic attraction, hydrogen bonding, van der Waals forces, and dipole forces. The internal energy, enthalpy, and entropy determined the exothermic and spontaneous uptake of MG.

Superparamagnetic iron oxide assisted transformation of graphene oxide nanolayers to nanoscrolls for supercapacitor electrode materials: Effect of morphology and electrolyte on supercapacitor performance

The study illustrates a facile preparative strategy of graphene oxide (GO) nanoscrolls through surface engineering of GO nanosheets by superparamagnetic iron oxide as the transformative and its application as a supercapacitor electrode. Superparamagnetic iron oxide particles acted like localized magnetic fields, which can establish inter particle attractive force within a GO nanosheet and metamorphose the morphology to nanoscrolls. The morphological transformation effectively restricted the restacking of exfoliated nanomaterials, thereby exterminating one of the major obstructions to acquire the expected electrochemical performances. The mechanism of scrolling process has been unveiled by preparing various combinations of GO:iron oxide and studying the sequential transformation in morphology using TEM, XRD and Raman followed by magnetization study and XPS. The critical ratio of GO:Iron Oxide was optimized at (1:6) and the combination was subjected for detailed electrochemical analysis under a three-electrode system using KOH and Na2S2O3 electrolytes. Cyclic voltammetry, impedance and galvanoscopic charge discharge study suggested an impressive electrode performance with specific capacitance, energy density and power density values of 849 Fg−1, 66.3 Whkg−1 and 416.7 Wkg−1, respectively in Na2S2O3 with an excellent cycle stability by retaining 85 % performance characteristics after 4000 cycles. The surface engineering method has been validated as a reversible strategy since successful unwinding and rewinding process of nanoscrolls made viable followed by the electrochemical performance evaluation. This has been further underlined the critical role of iron oxide for the improved storage/discharge performance via amending the morphology of GO.

Spontaneous formation of MoS2 nanoscrolls from flat monolayers with sulfur vacancies: a molecular dynamics investigation.

The unique physical properties exhibited by one-dimensional nanoscrolls assembled from nanosheets have propelled them into the spotlight of two-dimensional materials research. However, the self-scrolling mechanism of transition metal dichalcogenides has not been unveiled with an appropriate theoretical approach. In this paper, we systematically investigate the spontaneous formation of MoS2 nanoscrolls from flat monolayers by molecular dynamics simulations based on a reactive force field. The sulfur vacancies on one side break the atomic symmetry and the reconstruction acts as the driving force for the curling of the flat nanoribbon. If sulfur vacancies are arranged in a line, clear bending angles of the nanoribbon can be obtained and the angle relies on the direction of the line vacancy. With random sulfur vacancies on the top, spontaneous curling and a time-dependent scrolling process of the nanoribbon can be observed. The interplay between dangling bonds and van der Waals (vdW) interactions plays a pivotal role in the formation process of MoS2 nanoscrolls. With an increasing density of sulfur vacancies, the curvature of the nanoscrolls increases. Meanwhile, the scrolling rate accelerates and the time required for the formation of vdW structures decreases. These results provide theoretical insights into the fabrication of nanoscrolls and pave avenues for tailoring nanoscrolls with different morphologies.

Enhanced Adsorption of Toxic and Biologically Active Levofloxacin Residuals from Wastewater Using Clay Nanotubes as a Novel Fixed Bed: Column Performance and Optimization.

Kaolinite nanotube particles (KNTs) were synthesized by a chemical exfoliation and scrolling process in the existence of sonication waves. The KNT product was identified as a mesoporous material (12 nm in pore diameter) with high surface area (105 m2/g) and promising adsorption affinity for the levofloxacin antibiotic (LVOX) residuals in wastewater. The KNT particles were used as a fixed bed in the continuous adsorption column system for LVOX considering the essential variables. The investigation of the KNT fixed bed in a continuous column for 1800 min verified its suitability to reduce the LVOX content in 9 L of polluted solutions by 80.4%. This was recognized after using the KNT bed of 4 cm in height, a flow rate of 5 mL/min, a pH value of 8, a total flow interval of 1800 min, and an LVOX concentration of 10 mg/L. The regeneration study of the bed declared effective recyclability properties for the KNT particles in the LVOX adsorption column system. The dynamic properties of the KNT bed-based column system were explained based on Thomas, Adams–Bohart, and the Yoon–Nelson kinetic models. The LVOX adsorption reaction by KNTs follows Langmuir behavior with homogeneous and monolayer uptake form. The Gaussian energy (2.05 kJ/mol) and the thermodynamic parameters emphasized physical, spontaneous, and exothermic adsorption reactions for LVOX by KNTs.

Effective transformation of waste sunflower oil into biodiesel over novel K+ trapped clay nanotubes (K+/KNTs) as a heterogeneous catalyst; response surface studies

Abstract Kaolinite nanotubes were synthesized by exfoliation and scrolling process for kaolinite sheets and then doped with potassium ions (K+/KNTs) forming a novel basic catalyst of promising activity in the transesterification reactions. The synthetic K+/KNTs catalyst displayed well-developed nanotube morphology with an average pore diameter of 14.5 nm, surface area of 112 m2/g, and total basicity of 7.43 mmol OH/g. The catalyst was applied in the transesterification of waste samples for sunflower cooking oil based on statistical design. The statistical design was built based on the response surface methodology in conjunction with the central composite design. The obtained results considering the interaction between the different factors (time, temperature, catalyst loading, and methanol-to-oil ratio) reflected achieving maximum biodiesel yield of 98%. This value was obtained after conducting the test for 4 h using 6 wt, of K+/KNTs as catalyst loading in the presence of 15:1 methanol-to-oil ratio at a reaction temperature of 90 °C. Considering the suggested optimization solutions from the design, K+/KNTs catalyst can achieve biodiesel yield of 99.4% if the conditions adjusted at 5.5 h as time interval, 4.96 wt, % as loading, 103.3 °C as temperature, and 14.64:1 as a methanol-to-oil ratio. The properties of the biodiesel sample at the best conditions match the technical limitations of both EN 14214 and ASTM D-6751 standards.

Instantaneous oxidation of levofloxacin as toxic pharmaceutical residuals in water using clay nanotubes decorated by ZnO (ZnO/KNTs) as a novel photocatalyst under visible light source

Kaolinite nanotubes were synthesized by a simple scrolling process and decorated by ZnO nanoparticles as a novel nanocomposite (ZnO/KNTs). The synthetic ZnO/KNTs composite was characterized as an effective photocatalyst in the oxidation of levofloxacin pharmaceutical residuals in the water resources. The composite displays a surface area of 95.4 m2/g, average pore diameter of 5.8 nm, and bandgap energy of 2.12 eV. It is of high catalytic activity in the oxidation of levofloxacin in the presence of visible light source. The complete oxidation for 10 mg/L of levofloxacin was recognized after 55 min, 45 min, and 30 min with applying 30 mg, 40 mg, and 50 mg of ZnO/KNTs as catalyst dosage, respectively. Additionally, it achieved complete oxidation for 20 mg/L and 30 mg/L of levofloxacin after 45 min and 75 min, respectively using 50 mg as catalyst dosage. The degradation efficiency was confirmed by detecting the residual TOC after the treatment tests and the formed intermediate compounds were identified to suggest the degradation pathways. In addition to the oxidation pathway, the mechanism was evaluated based on the active trapping tests that proved the dominance of hydroxyl radicals as the essential active species. Finally, the ZnO/KNTs composite is of promising recyclability properties and achieved better results than several studied photocatalysts in literature.

Graphene nanoscrolls made from isolated carbon nanotubes with line defects

Molecular dynamics simulations demonstrate that graphene nanoscrolls (GNSs) can be fabricated by self-assembly of isolated carbon nanotubes (CNTs) with cut line defects. The scrolling process and energy analysis show that van der Waals interactions and π–π stacking are primary causes. The diameter and length of CNTs should meet some required conditions to guarantee the scroll configuration. The dependence of scroll-forming on temperature and edge structure is also investigated. It is remarkable that fissures with a helical pattern can greatly improve the scrolling ability of CNTs. Cutting defects provide a new way to fabricate pure GNSs without impurity from isolated CNTs.

Art Teaching and Creative Technologies: Interactive Graphic Novels Foster Thinking and Artistic Creation

At the beginning of the 21st century graphic novels faced a challenge. The appearance of comic strips on the internet creates more freedom. New features are provided to the creator and the reader. The remarkable form of graphic novels with the required choice of images and words is familiar to students of all levels due to their engagement with new technologies. Interactive graphic novels expand the boundaries of the novel with the particularity of using the audio-visual and verbal modes of expression. Interactive graphic novels immerse users into the storylines in an exciting way and allow them to become active participants in the content. They are not printed on good quality paper; interactive graphic novels are not books (not at least in the traditional, physical sense), but they maintain the same way of production and methodology. They are a hybrid type, with panels, visualisation and sound that resemble digital comics, videogames, but there is the fell/sense of reading. They have developed a complex vocabulary, visual, acoustic and verbal which has a significant influence on the understanding of the story. Larger narratives achieve the complexity and density of story. It is not just a scrolling process, that is it does not restrict the reader to a dull / restrictive navigation. It is especially important that they offer the user the freedom to navigate. The interactive collaboration of image, sound and word is a novel combination of elements in a web browser, offering a wealth of information, freedom of choice and practice of creativity. The subject matter is varied and the illustration does not depict the plot, but it is an integral part of the medium, as does the audio investment. Enrichment acts as a challenge that does not lead the reader to a surface reading. https://doi.org/10.26803/ijlter.17.6.10

Mimicking a Dog's Nose: Scrolling Graphene Nanosheets.

Inspired by the densely covered capillary structure inside a dog's nose, we report an artificial nanostructure, i. e., poly(sodium p-styrenesulfonate)-functionalized reduced graphene oxide nanoscrolls (PGNS), with high structural perfection and efficient gas sensing applications. A facile supramolecular assembly is introduced to functionalize graphene with the functional polymer, combined with the lyophilization technique to massively transform the planar graphene-based nanosheets to nanoscrolls. Detailed characterizations reveal that the bioinspired nanoscrolls exhibit a wide-open tubular morphology with uniform dimensions that is structurally distinct from the previously reported ones. The detailed morphologies of the graphene-based nanosheets in each scrolling stage during lyophilization are monitored by cryo-SEM. This unravels an asymmetric polymer-induced graphene scrolling mechanism including the corresponding scrolling process, which is directly presented by molecular dynamics simulations. The fabricated PGNS sensors exhibit superior gas sensing performance with reliable repeatability, excellent linear sensibility, and, especially, an ultrahigh response ( Ra/ Rg = 5.39, 10 ppm) toward NO2. The supramolecular assembly combined with the lyophilization technique to fabricate PGNS provides a strategy to design biomimetic materials for gas sensors and chemical trace detectors.

Architecting Graphene Oxide Rolled-Up Micromotors: A Simple Paper-Based Manufacturing Technology.

A graphene oxide rolled-up tube production process is reported using wax-printed membranes for the fabrication of on-demand engineered micromotors at different levels of oxidation, thickness, and lateral dimensions. The resultant graphene oxide rolled-up tubes can show magnetic and catalytic movement within the addition of magnetic nanoparticles or sputtered platinum in the surface of graphene-oxide-modified wax-printed membranes prior to the scrolling process. As a proof of concept, the as-prepared catalytic graphene oxide rolled-up micromotors are successfully exploited for oil removal from water. This micromotor production technology relies on an easy, operator-friendly, fast, and cost-efficient wax-printed paper-based method and may offer a myriad of hybrid devices and applications.

Rolling up two-dimensional sheets into nanoscrolls

Since discovery of graphene, various structures of two-dimensional (2D) sheets, such as nanoribbon, wrinkles, and folded layers, have been studied due to their unprecedented properties. Among them, a helical tube structure, which is called a nanoscroll, has been reported in naturally scrolled form of a graphene sheet. It has been expected that graphene nanoscrolls (GNSs) have exceptional properties, which are totally different from those of its constituent graphene sheet and multiwall carbon nanotubes (MWCNTs). Here we report a straightforward and controllable way to fabricate nanoscrolls of two dimensional sheets, such as graphene and molybdenum disulfide (MoS2). We rolled up graphene sheets into nanoscrolls by sweeping them up with vigorously generated bubbles in a solution. It was verified that there is no formation of significant defects after scrolling process and the graphene layers in a nanoscroll are decoupled. GNSs behave like randomly stacked monolayers without any coupling between the adjacent layers and show p-type electrical conductance, which is distinct from graphene’s electrical properties. In contrast, the stiffer MoS2 was folded, not scrolled during scrolling process. Raman shift and photoluminescence (PL) of folded MoS2 showed strong interlayer coupling between the stacked layers, which is opposite for the case of GNSs. To prevent this coupling effect, thin layer of lipids was deposited on the surface of MoS2 before scrolling process. Inserted lipid layers between MoS2 monolayers suppressed interlayer interactions, leading to enhanced PL intensity. Our work provides a novel way to fabricate various forms of 2D sheets, such as scrolled and folded structures, which are highly intriguing due to high possibility to seek for new physics in the scrolled structures of one-atom thick 2D sheets.

Scrolling up graphene oxide nanosheets assisted by self-assembled monolayers of alkanethiols.

We report a simple and novel method for the fabrication of high-quality nanoscrolls of graphene oxide (GO) and graphene oxide decorated with silver nanoparticles (GO-Ag) on a gold substrate through a scrolling process assisted by the self-assembly of alkanethiol monolayers. The yield and rate of the scrolling process were highly dependent on the lengths of the alkanethiol molecules, and could be well described by power law functions. Importantly, compared to nanosheets, nanoscrolls of GO and GO-Ag showed superior performance in humidity sensing due to their unique scrolled structures.

Fabrication and morphology tuning of graphene oxide nanoscrolls.

Here we report the synthesis of graphene oxide nanoscrolls (GONS) with tunable dimensions via low and high frequency ultrasound solution processing techniques. GONS can be visualized as a graphene oxide (GO) sheet rolled into a spiral-wound structure and represent an alternative to traditional carbon nano-morphologies. The scrolling process is initiated by the ultrasound treatment which provides the scrolling activation energy for the formation of GONS. The GO and GONS dimensions are observed to be a function of ultrasound frequency, power density, and irradiation time. Ultrasonication increases GO and GONS C-C bonding likely due to in situ thermal reduction at the cavitating bubble-water interface. The GO area and GONS length are governed by two mechanisms; rapid oxygen defect site cleavage and slow cavitation mediated scission. Structural characterization indicates that GONS with tube and cone geometries can be formed with both narrow and wide dimensions in an industrial-scale time window. This work paves the way for GONS implementation for a variety of applications such as adsorptive and capacitive processes.

A novel method for designing carbon nanostructures: Tailoring-induced self-scrolling of graphene flakes

Design and fabrication of functional carbon nanostructures is a challenging but meaningful mission for scientists to propel the development of nanotechnology, such as nanopharmacology, nanobiology and nanofluidic manipulation. In order to fabricate the carbon nanostructures, using forced-field-based molecular dynamics simulations, we proposed a feasible method to obtain the carbon nanostructures through tailoring-induced self-scrolling of graphene flakes. And the shapes of the carbon nanostructures could be regulated by controlling the tailoring patterns. We also analyzed the mechanism for the tailoring-induced self-scrolling of graphene flakes. By analyzing the scrolling process in detail, it was found that the van der Waals interactions were responsible for the formation of the carbon nanostructures. In addition, we also found that the tailoring could also induce the scrolling of Boron Nitride flakes, and this indicates that the tailoring might provide an universal method for self-assembly of two dimensional materials. This work is expected to trigger further studies on the design of nanostructures and the applications of these nanostructures in functional nanodevices.

Strain-driven self-rolling of hybrid organic–inorganic microrolls: interfaces with self-assembled particles

Strain driven micro and nanoroll fabrication is generally restricted to multilayer and multiprocessing systems, limiting the ability to exploit self-organization at different length scales. We have designed a hybrid organic–inorganic single-layered film with a surface that responds selectively to external stimuli, resulting in mechanical strain and self-rolling in one-step fabrication. The scrolling is initiated by water and any aqueous solution of molecules or colloidal particles. During scrolling, the different species in solution remain entrapped in the rolls; the constrained environment at the interface of the roll walls pushes the particles to organize into ordered structures. We used this rolling process to create self-assembled hybrid films with well-ordered layers of gold nanoparticles and opals of polystyrene nanospheres. These films also respond selectively to solvents, allowing the easy release of molecules/particles entrapped at the interface. Researchers from Japan and Italy have devised a one-step strategy to roll single-layer films into microtubes. Films of materials ranging from metals to semiconductors to polymers have previously been rolled up. They typically consist of two or more mismatched layers, so that the scrolling process relies on the strain between layers. The researchers have now prepared a self-rolling single-layer film by ‘sol–gel’ synthesis of a glycidoxy-organosilane derivative in basic conditions, spin-coating of the product obtained on a silica substrate and subsequent drying. The bottom part of the film formed, less condensed than its upper counterpart, takes up water preferentially. Simply dipping it in water creates a strain that is sufficient to provoke scrolling. Species such as molecules or particles can be trapped within the resulting microtubes, whose diameters are controlled by adjusting the processing conditions. This simple and convenient method may facilitate preparation of rolls for functional materials. Strain-driven micro- and nanorolls fabrication is generally restricted to multilayer and multiprocessing systems, which limit the possibility of exploiting the self-organization at different length scales. We have designed a hybrid organic–inorganic film whose surface shows a selective response to external stimuli, which induces mechanical strain and self-rolling in one-step–one-layer fabrication. The scrolling is initiated by water and any aqueous solution that also contains molecules or colloidal particles. During scrolling, the different species in solution remain entrapped in the rolls, giving rise to functional microrolls.

The growth of oriented titanate nanotube thin film on titanium metal flake

In this study, oriented titanate nanotubes thin films grow on titanium metal surface via a hydrothermal surface treatment process. A combined SEM and TEM investigation of the reaction products as the functions of reaction temperature, duration and concentration of NaOH solution reveal that several hundreds nanometer long nanotubes are formed by using 10 M NaOH at 110–150 °C for 6–48 h. A general formation mechanism of oriented titanate nanotube thin film was proposed in terms of the detailed observation of the products. The overall formation of titanate nanotubes can be summarized, as a sequence of layered trititanate formation, splitting and scrolling process.

Preparation of titanate nanotube thin film using hydrothermal method

In this study, the technology to grow nanotube thin film from dip-coated TiO 2 using hydrothermal method has been developed. The structure and stability of the film has been studied through the study of preparation parameters. A general formation mechanism of titanate nanotube thin film is proposed in terms of the detailed observation of the products via two dimensional surface scanning electron microscopy studies and transmission electron microscopy images. The overall formation can be summarized with three successive steps: (1) Transform TiO 2 to hydrated polytitanate layer; (2) Layered trititanate formation and growth process; (3) Formation of nanotube thin film via trititanate splitting and multilayer scrolling process of (100) planes around the c axis .