Sonication-assisted Method Research Articles

Indole-based NNN donor Schiff base ligand and its complexes: Sonication-assisted synthesis, characterization, DNA binding, anti-cancer evaluation and in-vitro biological assay

A novel indole based NNN donor Schiff base ligand and its Ni(II), Zn(II) and Cd(II) complexes have been synthesized using sonication-assisted method which is a highly efficient eco-friendly mechanism. The synthesized complexes have been characterized using elemental analysis, UV–Vis spectroscopy, mass spectrometry, FT-IR, and NMR and are optimized using DFT approach, which provided their theoretical framework. The stoichiometry between the ligand and the metal ions was also determined using Job's method. The thermogravimetric (TGA/DSC) analyses confirm the stability for all complexes at room temperature followed by thermal decomposition in different steps. DNA binding activities have been assessed by employing UV–visible and fluorescence spectra using the CT-DNA. The estimated intrinsic binding constant (Kb) for NiL, ZnL, and CdL complexes was 6.00 × 105, 5.58 × 105, and 4.7 × 105, respectively. In accordance with the Kb value, the quenching constant (Ksv) values of NiL, ZnL, and CdL are 5.59 × 105 M−1, 4.3 × 105 M−1, and 4.08 × 105 M−1 respectively. The anticancer properties have been assessed using MTT Assay. It has been found that the Ni(II) complex (NiL) is the most potent among the series with IC50 of 169 µg/mL. An in-vitro antioxidant experiment using DPPH was used to evaluate the synthesizedcomplexes' ability to scavenge free radicals. The findings indicated that the complexes exhibited notable antioxidant properties. The antioxidant property ZnL has been found to be the highest with an IC50 of 2.91 µg/mL and it follows the order is ZnL > NiL > CdL > L. Using the egg albumin denaturation technique, the anti-inflammatory property have been assessed, and the amount of protein denaturation inhibition has been computed. NiL has the highest % inhibition among the series studied. Comparatively, the metal complexes have been reported to exhibit higher biological activities than the prepared Schiff base ligand. The reason for the excellent biological properties observed in the metal complexes could be attributed to the incorporation of the electron-withdrawing CH3COO– during complexation. Molecular docking studies have been performed on the 2GYT protein and it has been found that the complexes have excellent binding affinity, with NiL having the lowest binding energy of −6.93 Kcal mol−1. The values suggested that NiL is more effective against HePG2 cancer cells, which is also in accordance with the MTT Assay results.

Room temperature synthesized layered CAU-17 MOFs for highly active and selective electrocatalytic CO2 reduction to formate

Modulating the morphology of metal-organic frameworks (MOFs) has been identified as an effective strategy for enhancing the electrocatalytic performance of CO2 reduction reactions (CO2RR). In this study, CAU-17 MOFs ([Bi(BTC)(H2O)]·2 H2O·MeOH) were prepared via a sonication-assisted method at room temperature, which is considered a simpler technique compared to the conventional hydrothermal method. Additionally, the morphology of CAU-17 MOFs was further regulated by incorporating a rare-earth metal (La), resulting in the observation of two distinct structures, i.e. CAU-17 hexagonal prism (CAU-17-HP) and CAU-17 layer (CAU-17-Layer). Compared to CAU-17-HP, CAU-17-Layer exhibits an excellent selectivity towards formate with the maximum Faradaic efficiency of 95.5% at − 1.1 VRHE in an H-cell. Subsequently, the limited catalytic activity of CAU-17-Layer was boosted by anchoring nano CeO2 onto its surfaces (CeO2 @CAU-17-Layer). The as-prepared composite catalyst demonstrated outstanding performance in the conversion of CO2 to formate, with a current density surpassing − 100 mA cm-2 at potentials more negative than − 1.0 VRHE and reaching − 200 mA cm-2 at − 1.5 VRHE in a flow cell. This study demonstrates the significant potential of morphology-engineered and rare-earth metals composited MOFs in facilitating highly efficient reduction of CO2.

Tunable 0D/2D/2D Nanocomposite Based on Green Zn-Doped CuInS2 Quantum Dots and MoS2/rGO as Photoelectrodes for Solar Hydrogen Production.

Charge separation, transmission, and light absorption properties are critical to determining the performance of photoelectrochemical (PEC) devices. An important strategy to control such properties is based on using heterostructured materials. Herein, a tunable zero-dimensional (0D)/two-dimensional (2D) heterostructure is designed based on quantum dots (QDs) and 2D nanosheets (NSs). Specifically, eco-friendly Zn-doped CuInS2 QDs prepared by hot injection were anchored on hierarchical (2D/2D) MoS2/rGO (MG) NSs through a facile sonication-assisted method to develop a 0D/2D/2D heterojunction-based photoelectrode for solar hydrogen production. The interfacial structure and band alignment between the proposed 0D QDs and 2D/2D MG NSs were engineered by modulating the Zn molar ratio during the QD synthesis. As proof of concept, the optimized 0D/2D/2D photoanode exhibits almost five times higher PEC activity than MG/CuInS2 and MoS2/Zn-CuInS2 NSs due to the enhanced light absorption, efficient charge separation, and transmission. Zn doping and the presence of graphene are essential in enhancing performance in the proposed heterostructure, reducing recombination of charge carriers, and improving sunlight absorption. This work shows how optimal band alignment control and carbon addition can facilitate charge transfer, enabling the development of highly efficient PEC devices based on 0D/2D/2D heterostructure nanocomposites.

Boron nitride nanosheet modified label-free electrochemical immunosensor for cancer antigen 125 detection

In this presented study, a new boron nitride nanosheets modified label-free electrochemical immunosensors were prepared for early detection of cancer antigen 125 (CA125). To aim for, boron nitride (BN) nanosheets were synthesized by conventional sonication-assisted method and then characterized. BN nanosheets were used for the surface modification of the working electrode of the screen-printed electrode (SPE). Anti CA125 antibody was then directly immobilized onto the electrode surface due to its natural affinity towards BN nanosheets. Modified electrodes were blocked with BSA and finally protected with Nafion. The newly synthesized label-free immunosensor demonstrated good detection properties to CA125 with a linear range of 5–100 U and a detection limit of 1.18 U/mL. The developed immunosensor also showed excellent reproducibility, selectivity, and stability profiles. Additionally, this immunosensor was successfully used for the detection of CA125 in artificial human serum samples along with the interfering agents. Also, it is expected that the prepared immunosensor should carry the good potential for point-of-care diagnosis in real cases.

Sonication-Assisted Method for Decellularization of Human Umbilical Artery for Small-Caliber Vascular Tissue Engineering.

Decellularized vascular grafts are useful for the construction of biological small-diameter tissue-engineered vascular grafts (≤6 mm). Traditional chemical decellularization requires a long treatment time, which may damage the structure and alter the mechanical properties. Decellularization using sonication is expected to solve this problem. The aim of this study was to develop an effective decellularization method using ultrasound followed by washing. Different power values of sonication at 40 kHz were tested for 2, 4, and 8 h followed by a washing procedure. The efficacy of sonication of decellularized human umbilical artery (sDHUA) was evaluated via DNA content, histological staining, mechanical properties, and biocompatibility. The sDHUAs were further implanted into rats for up to 90 days and magnetic resonance angiography (MRA) was performed for the implanted grafts. The results demonstrated that treatment of human umbilical artery (HUA) by sonication at ultrasonic power of 204 W for 4 h followed by washing for 24 h in 2% SDS buffer could eliminate more than 90% of cells and retain similar mechanical properties of the HUA. Recellularization was assessed by scanning electron microscopy (SEM), which indicated that sDHUA provided niches for human umbilical vein endothelial cells (HUVECs) to reside, indicating in vitro cytocompatibility. Further implantation tests also indicated the fitness of the sonication-treated HUA as a scaffold for small-caliber tissue engineering vascular grafts.

In-situ exfoliation of graphitic carbon nitride with metal-organic framework via a sonication-assisted approach for dispersive solid-phase extraction of perfluorinated compounds in drinking water samples

Monitoring the levels of perfluorinated compounds (PFCs) in the environment is of vital importance, owing to their sustained environmental presence, extensive distribution, and associated health risks. The development of cost-effective and efficient sorbents for the establishment of sensitive analytical methods is critical for achieving trace-level detection. In this study, a graphitic carbon nitride (g-C3N4)-based sorbent is synthesized by a facile sonication-assisted method exfoliated by zeolitic imidazolate framework-67 (ZIF-67) in situ. The novel ZIF-67/g-C3N4 composites were systematically characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and N2 adsorption–desorption analysis, exhibiting good dispersity and a large surface area. Moreover, molecular dynamics simulations indicated that g-C3N4 structures can be effectively exfoliated by the introduced ZIF-67 molecules. The hybrid material was successfully utilized as a dispersive solid-phase extraction sorbent, and the extraction factors were systematically optimized by response surface methodology. Under optimal conditions, the synthesized sorbent exhibited desirable linear correlations (R2 > 0.99), a low detection limit (0.3–2 ng L−1), and good repeatability (relative standard deviation <15%, n = 6). The developed method was applied for the analysis of natural and spiked water samples. The study demonstrated that the ZIF-67/g-C3N4 composites are promising materials for pollutant adsorption from drinking water samples.

Extraordinary macroscale lubricity of sonication-assisted fabrication of MoS2 nano-ball and investigation of in situ formation mechanism of graphene induced by tribochemical reactions

We first fabricate MoS2 nano-ball in isopropanol using sonication-assisted method. We systematically probe the lubrication mechanism of MoS2 nano-ball in isopropanol. Hydroxylated MoS2 nano-ball could effectively reduce the contact area for GCr15 steel balls and possess superior load-capacity and make the tribosystem achieve ultra-low friction and wear under 98 or 196 N and 600 rpm. For comparison, the lubricity of tribosystem sliding in isopropanol is conducted. Interestingly, graphene layers are formed sliding under 196 N and 600 rpm, the graphene-based transfer film on GCr15 steel ball makes the lubrication condition fast transfer from mixed lubrication condition to full film lubrication condition, which results in high friction and wear. The formation mechanism of graphene is discussed and proposed in details.

Combination of cell disruption method and pH variation as pre-treatment for lipid extraction of Nannochloropsis sp.

The quantity of fossil-based fuel also has depleted due to over-exploitation. Therefore, environmentally friendly and more sustainable energy resources are being searched to fill in the energy supplies in the future. Microalgae have been considered by the researcher as alternative biofuel feedstock due to their high lipid content. Lipid extraction is one of the crucial steps in biofuel production from microalgae. The aim of this study was to analyze the best combination of pre-treatments to obtain microalgae lipid for biodiesel. The utilization of different cell disruption methods, including sonication and microwave, combined with pH variation (3, 5, 7) was implemented on microalgae Nannochloropsis sp. The experiment shows cell disruption with sonication and combined with low pH 3 of oil extraction from Nannochlorpsis sp. resulted in the highest yield of oil content (1.15% gr/gr dry weight). The lipid extracted from each pH pre-treatment were analyzed using GCMS for its fatty acid profile. The best pretreatments combination was obtained from lipid extraction from pH 5 and sonication-assisted method.

Fabrication and investigation on the ultra-thin and flexible Ti3C2Tx/co-doped polyaniline electromagnetic interference shielding composite films

Polyaniline (PANI) was co-doped using dodecylbenzenesulfonic acid (DBSA) and hydrochloric acid (HCl), and few-layered Ti3C2Tx was prepared via ionic intercalation followed by sonication-assisted method. Then the Ti3C2Tx/co-doped PANI (Ti3C2Tx/c-PANI) electromagnetic interference (EMI) shielding composite films were prepared by vacuum assisted filtration. FTIR, XPS, XRD, and Raman indicated that c-PANI was successfully synthesized. XRD, SEM, AFM, and TEM revealed the successful preparation of few-layered Ti3C2Tx. The electrical conductivity, EMI shielding effectiveness (EMI SE), and tensile strength of the Ti3C2Tx/c-PANI EMI shielding composite films were all increased with increasing the mass fraction of Ti3C2Tx. When the mass ratio of Ti3C2Tx to c-PANI was 7:1, the thickness of Ti3C2Tx/c-PANI composite film was only 40 μm. And the corresponding electrical conductivity, EMI SE, and tensile strength were significantly enhanced to 24.4 S/cm, 36 dB, and 19.9 MPa, which were 81, 2.3, and 7.7 times those of pure c-PANI film (0.3 S/cm, 16 dB, and 2.6 MPa), respectively. Our fabricated Ti3C2Tx/c-PANI EMI shielding composite films present potential applications in the high-tech fields with demand for ultrathin, lightweight, and flexible EMI shielding materials.

3D Ti3C2Tx MXene/C hybrid foam/epoxy nanocomposites with superior electromagnetic interference shielding performances and robust mechanical properties

Few-layered Ti3C2Tx MXene was prepared by ionic intercalation and sonication-assisted method. Porous three-dimensional (3D) Ti3C2Tx MXene/C hybrid foam (MCF) was fabricated by sol-gel followed by thermal reduction. The MCF/epoxy EMI shielding nanocomposites were obtained via vacuum-assisted impregnation followed by curing process. When the mass fraction of MCF was 4.25 wt% (MCF-5), the MCF-5/epoxy EMI shielding nanocomposites exhibited the optimal electrical conductivity of 184 S/m and the maximum EMI SE of 46 dB, 3.1 × 104 and 4.8 times higher than that of MCF-0/epoxy nanocomposites (without Ti3C2Tx MXene), respectively. Furthermore, the corresponding Young's modulus of 3.96 GPa and hardness of 0.31 GPa was increased by 13% and 11%, respectively. Conductive networks can realize the attenuation and dissipation of electromagnetic waves by multiple reflection & reabsorption, and absorption is main shielding mechanism. Unique 3D conductive networks of MCF would expand wider application of the Ti3C2Tx MXene/polymer-based nanocomposites in high-tech EMI shielding fields.

Fabrication on the annealed Ti3C2Tx MXene/Epoxy nanocomposites for electromagnetic interference shielding application

Few-layered Ti3C2Tx MXene was fabricated by ionic intercalation and sonication-assisted method, followed by thermal reduction at medium-low temperature. Then annealed Ti3C2Tx/epoxy electromagnetic interference (EMI) shielding nanocomposites were obtained by solution casting method. XRD, SEM, AFM and TEM indicated the successful preparation of few-layered Ti3C2Tx. FTIR, XPS and XRD showed that thermal reduction removed partial polar groups on the surface of Ti3C2Tx with no by-product. For a fixed Ti3C2Tx loading, compared with Ti3C2Tx/epoxy EMI shielding nanocomposites, the annealed Ti3C2Tx/epoxy EMI shielding nanocomposites exhibited relatively higher electrical conductivity and excellent EMI shielding effectiveness (SE). When the mass fraction of annealed Ti3C2Tx was 15 wt%, the annealed Ti3C2Tx/epoxy EMI shielding nanocomposites presented the optimal electrical conductivity of 105 S/m and EMI SE of 41 dB, 176% and 37% higher than that of 15 wt% Ti3C2Tx/epoxy EMI shielding nanocomposites. Furthermore, the 5 wt% annealed Ti3C2Tx/epoxy EMI shielding nanocomposites exhibited the optimal Young's modulus of 4.32 GPa and hardness of 0.29 GPa, respectively.

A 2D metal-organic framework/Ni(OH)2 heterostructure for an enhanced oxygen evolution reaction.

2D metal-organic frameworks (MOFs) are widely regarded as promising electrocatalysts for the oxygen evolution reaction (OER). This results from their inherent properties such as a large portion of surface coordinatively unsaturated metal atoms, rapid mass transfer and enhanced conductivity. However, 2D MOFs have a strong tendency to aggregate, which severely limits their potential application in the OER. Here, novel 2D Ni-BDC/Ni(OH)2 (BDC stands for 1,4-benzenedicarboxylate, C8H4O4) hybrid nanosheets are synthesized via a facile sonication-assisted solution method. Because of the rational material design, the large surface area of Ni-BDC is maintained. Significantly, after coupling, the electronic structure of Ni atoms in the Ni(OH)2 component is well modified, leading to the generation of Ni cations with higher oxidation states, which are desirable for the OER. As-prepared Ni-BDC/Ni(OH)2 exhibits high activity, favorable kinetics and strong durability towards the OER. Specifically, the OER current density of Ni-BDC/Ni(OH)2 is 82.5 mA cm-2 at 1.6 V versus a reversible hydrogen electrode (RHE), which is significantly greater than those of Ni-BDC (5.5 times), Ni(OH)2 (20.6 times) and Ir/C (3.0 times). Moreover, the sonication-assisted method developed in this work can be readily adapted for the preparation of various 2D MOF-based hybrid functional materials.

Green solvent assisted synthesis of cesium bismuth halide perovskite nanocrystals and the influences of slow and fast anion exchange rates.

Replacing lead in halide perovskites to address the concerns of their toxicity and stability has driven a recent surge in research toward alternative lead-free perovskite materials. Lead-free all inorganic cesium bismuth halide (Cs3Bi2X9) perovskite nanocrystals have attracted attention in recent years due to the air-stability and non-toxic nature of bismuth. Herein, we demonstrate a facile sonication-assisted approach for the preparation of all-inorganic cesium bismuth iodide (Cs3Bi2I9) perovskite nanocrystals (NCs) using propylene carbonate as a green, alternative solvent. The photoluminescence (PL) spectra of the Cs3Bi2X9 NCs have a peak emission that can be tuned from 410 to 550 nm by controlling the composition of the NCs through an anion exchange reaction using tetraalkylammonium halides as a source of halide ions. The rate of this anion exchange reaction is demonstrated to have a significant influence on the dimensions of the NCs obtained from the parent Cs3Bi2I9 NCs. The PL emission of these nanocrystals is predominately due to exciton recombination processes. The NCs also exhibit air-stability for at least 150 days.

Development of LTA zeolite membrane from clay by sonication assisted method at room temperature for H2-CO2 and CO2-CH4 separation

In this work, sodium aluminosilicate zeolite powder and membranes were synthesized by ultrasonic irradiation at room temperature using montmorillonite clay as precursor material. For comparison, same zeolite powder and membranes were synthesized at 100 °C also. The synthesized zeolites were characterized by X-ray diffraction (XRD), infrared (IR) spectral analysis, and field-emission scanning electron microscopy (FESEM). XRD and IR results showed that phase pure mainly LTA phase was formed after 15 days of aging at room temperature. By using the zeolite powders as seeds, membranes were synthesized on clay alumina support tubes at room temperature and also at 100 °C. In both the cases membranes were formed on support surface. The membrane thickness was found to be 15 μm. The performances of the membranes were evaluated by single gas as well as mixture gas permeation measurement for H2-CO2 and CO2-CH4 respectively. The H2–CO2 and CO2-CH4 separation selectivity for the mixture gas of the membrane was found to 16.2 and 20.9 at room temperature respectively. To the best of our knowledge, there is no report of synthesis of zeolite membrane at room temperature using clay as raw materials. For the first time we have reported the synthesis of alumino-silicate zeolite membrane on clay alumina support surface using clay as starting material by sonochemical method at room temperature.

Facile sonication‐assisted synthesis and characterisations of silica decorated graphene nanocomposites

This work demonstrates the fabrication of a composite nanomaterial consisting of spherical silica nanoparticles decorated onto the graphene sheets which has been prepared by the sonication-assisted method. Graphene/silica nanocomposites were fabricated by the hydrolysis of tetraethyl orthosilicate in the presence of graphene oxide which has been obtained by modified Hummer's method. The obtained nanostructures were characterised by the X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD analysis depicts the coexistence of silica and graphene in the composite material. The morphology of synthesised silica–graphene nanocomposites was characterised by SEM and TEM. All images have been observed in the presence of SiO2 nanoparticles of similar sizes which were grafted on the surface of graphene effectively. More significantly, the BET analysis revealed that the silica decorated graphene nanocomposites exhibit enhanced surface area than bare silica and graphene.

CO2 oxidation of carbon nanotubes for lithium-sulfur batteries with improved electrochemical performance

The fabrication of high-performance cathodes with high sulfur content is essential for the practical realization of lithium–sulfur (Li–S) systems. The preparation of high-sulfur-content electrodes is currently hindered by poor dispersion of the conductive agents; nonuniformly distributed conductive agents cannot provide sufficient sulfur-loading sites, thereby resulting in aggregation of sulfur/Li2S and severe polarization. To deal with this issue, we prepare CO2 modified carbon nanotube (CNT)-based cathodes for Li–S batteries. CNTs are exposed to CO2 at 900 °C, resulting in uniformly distributed negative charges on the external surface of the tubes; the electrostatic repulsion facilitated the dispersion of CNTs. Compared with the previous work on CNTs prepared by air oxidation (denoted as air-CNTs), the dispersions of the CO2-treated CNTs (denoted as CO2-CNTs) are more stable, which allows higher sulfur loading and improves sulfur utilization. A free-standing CO2-CNT&S electrode with a sulfur content of 80 wt% is fabricated through a sonication-assisted method. The excellent dispersion of the CO2-CNT&S network results in little kinetic barriers, low polarization, and fast charge transport at the interface of the electrode and electrolyte. The CO2-CNT&S electrode delivers a lower capacity fading rate and superior rate performance compared with the air-CNT&S electrode.

Encapsulation of carotenoids in emulsion-based delivery systems: Enhancement of β-carotene water-dispersibility and chemical stability

β-carotene is a lipophilic micronutrient that is important for maintaining human health and wellbeing. However, the utilization of β-carotene in functional foods and dietary supplements is currently limited due to its poor water-dispersibility and chemical stability. A β-carotene-enriched delivery system was therefore developed to overcome these problems using a microfluidizer to produce an oil-in-water emulsion. The fabrication process was optimized to enhance the water-dispersibility and chemical stability of the encapsulated β-carotene. A sonication-assisted method was more effective (1.73 ± 0.27%, w/w) in dissolving β-carotene in the lipid phase than commonly used heating method (1.21 ± 0.16%, w/w). Powdered versions of the β-carotene-enriched emulsion were produced using either spray or freeze-drying. Higher β-carotene retention was obtained in freeze-dried powders than spray dried ones (95% vs 15%–28%). Moreover, the freeze-dried powder had better water-dispersibility and lower moisture content. In conclusion, sonication-assisted dissolving method together with freeze drying might be an effective method to prepare β-carotene-enriched functional foods and dietary supplements.

Biocompatible Carbon Dots Clusters with Tunable Sizes for Bioimaging Application

Carbon dots (Cdots) have been widely applied in labeling cellular or subcellular targets with high resolution due to their small sizes and benign biocompatibility. However, their use for in vivo application suffered from the rapid renal clearance due to their tiny size (c.a. [Formula: see text]6[Formula: see text]nm in diameter). To overcome the drawback, we herein report a sonication assisted method for the preparation of Cdots clusters with tunable sizes. Pluronic F127 was used as the carrier to form the clusters and the feeding ratio of the Cdots to F127 was varied in order to tune the sizes of clusters. The clusters were also successfully demonstrated in cell imaging applications with high brightness. Together with their low cytotoxicity, the clusters are potential for bioimaging applications. Hence, this work provides a convenient engineering strategy to prepare Cdots clusters with tunable sizes for bioimaging applications.

A versatile sonication-assisted deposition–reduction method for preparing supported metal catalysts for catalytic applications

This work aims to develop a rapid and efficient strategy for preparing supported metal catalysts for catalytic applications. The sonication-assisted reduction–precipitation method was employed to prepare the heterogeneous mono- and bi-metallic catalysts for photocatalytic degradation of methyl orange (MO) and preferential oxidation (PROX) of CO in H2-rich gas. In general, there are three advantages for the sonication-assisted method as compared with the conventional methods, including high dispersion of metal nanoparticles on the catalyst support, the much higher deposition efficiency (DE) than those of the deposition–precipitation (DP) and co-precipitation (CP) methods, and the very fast preparation, which only lasts 10–20s for the deposition. In the AuPd/TiO2 catalysts series, the AuPd(3:1)/TiO2 catalyst is the most active for MO photocatalytic degradation; while for PROX reaction, Ru/TiO2, Au–Cu/SBA-15 and Pt/γ-Al2O3 catalysts are very active, and the last one showed high stability in the lifetime test. The structural characterization revealed that in the AuPd(3:1)/TiO2 catalyst, Au–Pd alloy particles were formed and a high percentage of Au atoms was located at the surface. Therefore, this sonication-assisted method is efficient and rapid in the preparation of supported metal catalysts with obvious structural characteristics for various catalytic applications.

Ultrasonication-Assisted Hydrothermal Synthesis of Ultralong TiO2 Nanotubes

Abstract Ultralong titanate nanotubes were synthesized by treating general anatase TiO2 in alkaline solution using a facile sonication-assisted hydrothermal method. The as-synthesized products via sonication and sonication-hydrothermal treatment were characterized by SEM, TEM, OM and XRD. The effects of sonication power, sonication frequency and sonication temperature on the morphology and the crystal structure of the products were investigated. The results show that in the range of ultrasonic power (200, 300, 400, 500 W) and frequency (20, 40, 80 kHz), titanium dioxide particles were swelled in alkali aqueous solution to get the hedgehog flocculent intermediate products by ultrasonic irradiation when the ultrasonic temperature was equal or higher than 60 °C; several tens of microns long titanate nanotubes were achieved using the intermediate products as raw materials under the mild hydrothermal conditions of 90 °C and 5 h. The possible formation mechanism for ultralong titanate nanotubes was also discussed. The hedgehog floccules synthesized by sonication play an important role to synthesize the several tens of micrometers long nanotubes.