Phase transition between nanostructures of titanate and titanium dioxides via simple wet-chemical reactions

Cobalt ions-derived nanoenzyme array for endosseous neural network reconstruction and osseointegration

Interactions between bone cells and neurocytes are crucial for endosseous nerve and ensuing bone regeneration. However, absence of neural stem cells in bone makes the innervation of implant osseointegration a major challenge. Herein, a nanorod-like array of sodium hydrogen titanate (ST) co-doped with Co2+ and Co3+, namely STCh that behaves as a reactive oxygen species (ROS)-scavenging enzyme, was hydrothermally formed on Ti substrate. We show that the doped Co2+ and Co3+ locate at TiO6 octahedral interlayers and within octahedra of STCh lattice, appearing releasable and un-releasable, respectively, leading to an increase in Co3+/Co2+ ratio and enzyme activity of the array with immersion. The nanoenzyme-released Co2+ triggers macrophages (MΦs) towards M1 phenotype, then the nanoenzyme scavenges extracellular ROS inducing M1-to-M2 transition. The neurogenic factors secreted by STCh-regulated MΦs, in combination with the released Co2+, promote mesenchymal stem cells to differentiate into neurons and Schwann cells compared to sole Co2+and ST. STCh array greatly enhances nerve reconstruction, type-H capillary formation and ensuing osseointegration in normal rat bone, and antibacteria via engulfing S. aureus by MΦs and osteogenesis in infective case. This nanoenzyme provides an alternative strategy to orchestrate endosseous nerve regeneration for osseointegration without loading exogenous neurotrophins in implants.

The Role of Cerium Valence in the Conversion Temperature of H2Ti3O7 Nanoribbons to TiO2-B and Anatase Nanoribbons, and Further to Rutile

CeO2-TiO2 is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO2 nanostructures decorated with CeO2 nanoparticles at the surface. As the precursor, we used H2Ti3O7 nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF-STEM mapping of the Ce4+-modified nanoribbons revealed a thin continuous layer at the surface of the H2Ti3O7 nanoribbons, while Ce3+ cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeO2 nanoparticles on the surface of the TiO2 nanoribbons, whose size increased with the calcination temperature. The use of Ce4+ raised the temperature required for converting H2Ti3O7 to TiO2-B by approximately 200 °C, and the temperature for the formation of anatase. For the Ce3+ batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state.

Self-Seeding Synthesis of Hierarchically Branched Rutile TiO2 for High-Efficiency Dye-Sensitized Solar Cells

This study presents a unique and straightforward room temperature-based wet-chemical technique for the self-seeding preparation of three-dimensional (3D) hierarchically branched rutile TiO₂, abbreviated HTs, employing titanate nanotubes as the precursor. In the course of the synthesis, spindle-like rutile TiO₂ and the intermediate anatase phase were first obtained through a dissolution/precipitation/recrystallization process, with the former serving as the substrates and the latter as the nucleation precursor to growing the branches, which finally gave birth to the production of 3D HTs nanostructures. When the specifically created hierarchical TiO₂ was used as the photoanode in dye-sensitized solar cells (DSCs), a significantly improved power conversion efficiency (PCE) of 8.32% was achieved, outperforming a typical TiO₂ (P25) nanoparticle-based reference cell (η = 5.97%) under the same film thickness. The effective combination of robust light scattering, substantial dye loading, and fast electron transport for the HTs nanostructures is responsible for the remarkable performance.

In Situ TEM under Optical Excitation for Catalysis Research

In situ characterization of materials in their operational state is a highly active field of research. Investigating the structure and response of materials under stimuli that simulate real working environments for technological applications can provide new insight and unique input to the synthesis and design of novel materials. Over recent decades, experimental setups that allow different stimuli to be applied to a sample inside an electron microscope have been devised, built, and commercialized. In this review, we focus on the in situ investigation of optically active materials using transmission electron microscopy. We illustrate two different approaches for exposing samples to light inside the microscope column, explaining the importance of different aspects of their mechanical construction and choice of light source and materials. We focus on the technical challenges of the setups and provide details of the construction, providing the reader with input on deciding which setup will be more useful for a specific experiment. The use of these setups is illustrated using examples from the literature of relevance to photocatalysis and nanoparticle synthesis.

Nonequilibrium phase transitions of a nematic liquid crystal under ac field-driven electroconvection

We report on phase transitions between isotropic and nematic liquid crystal phases in nonequilibrium systems (NESs). ac field-driven electroconvection (EC) provides an NES, which can be well controlled by the voltage V and frequency f; it arises electrohydrodynamically at a threshold voltage V_{c}. In continuous cooling and heating processes with various rates R, the critical temperature T_{c} was determined at a critical time t_{c} for phase transitions. Moreover, the morphological and dynamical features in the phase transitions were examined using an electro-optical image processing method. In comparison with an equilibrium system (V=0), two typical turbulent ECs (i.e., NESs), which are called dynamic scattering mode 1 (DSM1 for V>V_{c}) and DSM2 (for V≫V_{c}), were examined to understand the nonequilibrium phase transitions. In particular, our results show that in high voltage-induced turbulence (i.e., DSM2), T_{c} can be determined effectively without considering R; this provides a possibility for a material technology application in nonequilibrium-based circumstances.

Monazite LaPO4:Eu3+ nanorods as strongly polarized nano-emitters

Orientation analyses of macromolecules or artificial particles are vital for both fundamental research and practical bio-applications. An accurate approach is monitoring the polarization spectroscopy of lanthanide-doped nanocrystalline materials. However, nanomaterials are often far from ideal for the colloidal and polarization luminescence properties. In the present study, we synthesize well-dispersed LaPO₄:Eu³⁺ nanomaterials in an anisotropic rod shape. Microwave heating with excess addition of phosphate precursor invokes a rapid phase transition of rhabdophane into monazite. The colloidal stability of the nanorod suspension is outstanding, demonstrated by showing liquid crystalline behaviors. The monazite nanorods are also superior in luminescence efficiency with limited defects. The emission spectrum of Eu³⁺ consists of well-defined lines with prominent polarization dependencies for both the forced electric dipole transitions and the magnetic dipole transitions. All the results demonstrate that the synthesized monazite nanorods can serve as an accurate probe in orientation analyses and potential applications, such as in microfluidics and biological detections.

TiO2 nanofibers fabricated by electrospinning technique and degradation of MO dye under UV light

Titanium dioxide (TiO2) nanofibers were synthesized by electrospinning to optimize the photocatalytic action efficiency. The synthesis of the fibers was carried out at four different wt% concentrations: 8, 9, 10 & 11% of polymer polyvinylpyrrolidone (PVP). The TiO2 fibers were further calcined at 700 °C to get powder form. The uncalcinated and calcined TiO2 nanofibers were characterized by using X-Ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM) and UV-Visible spectroscopy. Raman spectroscopy confirmed the rutile phase of the calcined TiO2nanofibers in powder form with a crystallite size of 34–38 nm. The surface morphology of the uncalcinated and calcined TiO2 nanofibers was examined by SEM and the fiber diameter found to be 360–540 nm. The optical bandgap of the calcined TiO2 nanofibers was found in the range of 3.29–3.24 eV. The photocatalytic activity of the TiO2 nanofibers as examined for uncalcinated and calcined nanofibers, methyl orange (MO) dye degraded up to 98 and 78%, respectively in 180 min under the exposure of UV light. Uncalcinated TiO2 nanofibers were found more suitable for degradation of MO dye as compared to calcined nanofibers.

Indoor gas phase photoactivity of yttrium modified titanate films for fast acetaldehyde oxidation

Photoactive materials hold structural and catalytic features that make them particularly suitable for environmental applications and in the present work, protonated H₃Ti₃O₇-Y nanofiber-like materials were prepared via the microwave assisted hydrothermal technique. The as-prepared nanofibers exhibited high surface area with titanate structure. The nanofibers, before and after yttrium incorporation, were well-distributed and the fibrous morphology could be observed clearly; as the yttrium loading increased, ribbons and the anatase phase were formed. Practical films of these nanofibers confirmed their likely UV-photoactive properties with 200 ppm of acetaldehyde degradation within 25 min in the presence of 50% of humidity. Activity retention was achieved, keeping stability for 2 consecutive cycles at room temperature. Nowadays, the increase in home office work sets human health at risk, for the exposure to toxic volatile organic compounds and microorganisms such as viruses and bacteria is more frequent indoors. In this context, the synthesized photoactive yttrium-titanate films stand as upcoming practical UV-driven materials for cleaning pollution that concentrated urban activity and indoor environments.

Sr2+ sorption property of seaweed-like sodium titanate mats: effects of crystallographic properties

Layered sodium titanate is a typical ion-exchanger for water purification aimed at removing cationic heavy metals and radionuclides. The material design of an ion-exchanger is effective for cation removal. For that purpose, understanding the basic impacts of crystallographic properties such as crystal size, morphology, and phase is critical for developing highly functional nanoscale ion-exchangers. In this study, we investigate the principal relationship between the crystallographic properties of seaweed-like sodium titanate mats (SSTs), which consist of a dititanate (H_xNa_2−xTi₂O₅) phase of nanofibers synthesised by the alkaline hydrothermal method and their Sr²⁺ sorption mechanism. A trititanate (H_xNa_2−xTi₃O₇) phase, which has a micro-sized fibre morphology, was also synthesised using the same method by adjusting the NaOH concentration. The SST demonstrates a high ion-exchange selectivity of Sr²⁺ against H⁺ and a high maximum sorption capacity (2 mmol g⁻¹), which was four times higher than that of the trititanate phase (0.49 mmol g⁻¹). In contrast, the trititanate phase, which is the comparison target, had a low Sr²⁺ ion-exchange selectivity and precipitated SrCO₃. We conclude that these differences in Sr²⁺ sorption mechanisms were derived from not only the unique morphology but also the crystal structure of sodium titanates. Although almost all of the Na⁺ in dititanate with lamellar structure was consumed by the ion-exchange reaction, some Na⁺ remained in the trititanate because there are two sites in the zigzag layered structure. These findings on the crystallographic properties of SST for Sr²⁺ sorption may contribute to the functionalisation of a nanoscale ion-exchanger.

Seaweed-like sodium titanate mats (SSTs) have excellent sorption capacity of Sr²⁺ compared to sodium trititanate monodispersed nanofibers due to the sodium dititanate structure and its unique nano/micro-scale morphologies.

Insights into mesoporous MCM-41-supported titania decorated with CuO nanoparticles for enhanced photodegradation of tetracycline antibiotic

In this research, tetracycline photodegradation under UV light was investigated over bare TiO₂ and a series of MCM-41 supported CuO-TiO₂ heterojunctions varying in CuO content with the intent of exploring the effect of MCM-41 presence and especially, CuO addition. Several techniques including XRD, FESEM, EDX, DRS, BET, and PL were applied to characterize the physicochemical and photophysical properties of synthesized nanocomposites. It was found that the co-existence of MCM-41 and CuO enhances the surface dispersion of Ti species, leading to less number of agglomerates and smaller particle size of TiO₂, which it promoted photophysical properties and reinforced the interaction of surface species with the support and thereby, the photosite leachings were lessened. However, the excessive loadings alleviate the synergetic effect of CuO due to the significant decrease of surface area, the appearance of more number of agglomerations, and surface coverage of MCM-41. The results revealed that CuO addition not only enhances the photocatalytic activity of TiO₂/MCM-41 but also makes it reusable in further experiments. It was also observed that the highest photodegradation of tetracycline was obtained over TiO₂-CuO/MCM-41 nanocomposite containing 5 wt% CuO. It is attributed to less electron-hole recombination, appropriate band gap, smaller number of agglomerations, and more uniform dispersion of photosites. Following the obtained results, a possible reaction mechanism was also proposed.

One-Pot Synthesis of Anatase, Rutile-Decorated Hydrogen Titanate Nanorods by Yttrium Doping for Solar H2 Production

We have prepared yttrium (Y)-doped hydrogen titanate nanorods (HTN) by a microwave-assisted hydrothermal method. Y-doped HTN showed much improved photocatalytic activities for both H₂ evolution and dye decomposition. H₂ production from a methanol-water solution under UV-visible light for 7 h was enhanced by a factor of 5.5 with 1 wt % Y-doping. Doping with Y³⁺ ions reduced the band gap of HTN by ∼0.28 eV and induced new phases of anatase and rutile. High photocatalysis by Y-doping was attributed to enhanced light absorption (smaller band gap) and effective charge separation (heterojunction). To optimize H₂ production, a series of experiments examining effects of doping concentrations and non-noble surface metal (e.g., Ni, Cu, Co) loading were carefully performed. Y-doping in this work is a new and promising approach for synthesizing highly active HTN by producing the HTN/rutile/anatase heterostructure within the one-pot method.

Effect of aspect ratios of rutile TiO2 nanorods on overall photocatalytic water splitting performance

The spatial separation of reduction and oxidation reaction sites on the different facets of a semiconductor is an ideal and promising route for overall photocatalytic water splitting due to efficient charge carrier separation. Rutile TiO2 has separate oxidation and reduction crystal facets and can be used to achieve direct splitting of pure water under ultraviolet (UV) light irradiation. In order to improve the rate of water oxidation reaction, the ratio of different crystal facets of rutile should be regulated controllably. However, the preparation of rutile TiO2 architecture has been limited by the availability of synthetic techniques. In this study, rutile TiO2 nanorods with various aspect ratios were accurately prepared in the presence of Cl- anions and H+ cations, which were found to play a crucial role in forming the morphology of rutile TiO2 nanorods. In addition, the mechanism involving the growth of rutile TiO2 nanorods with different aspect ratios is proposed. Rutile TiO2 nanorods with a high proportion of oxidative (111) facets provided higher overall water splitting reactivity.

Synthesis of core-shell magnetic titanate nanofibers composite for the efficient removal of Sr(ii)

We report a facile approach for the fabrication of Fe₃O₄@titanate fibers magnetic composite through a hydrothermal method and sol-gel process. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microsphere (TEM), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDX). Owing to the high ion exchange capacity of the functional titanate layer, the obtained core-shell structured magnetic microspheres exhibited high removal efficiency towards strontium from wastewater. The effects of contact time and Sr(ii) concentration on the uptake amount of strontium were systematically investigated. The results indicated that the adsorption equilibrium can be reached within 30 min, and the maximum exchange capacity was approximately 37.1 mg g^-1. Moreover, the captured Sr(ii) can be eluted using 5 wt% of EDTA(Na), which contributed to the reduction of waste volume. Based on the experimental results of ion exchange process and X-ray photoelectron spectroscopy (XPS), a possible adsorption mechanism was proposed. This work provided a facile approach to synthesize magnetic functional nanocomposites for wastewater treatment.

The Role of Ligands in the Chemical Synthesis and Applications of Inorganic Nanoparticles

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

Electrochemical Corrosion Behavior and Mechanical Properties of Nanocrystalline Ti⁻6Al⁻4V Alloy Induced by Sliding Friction Treatment

A nanograined (NG) layer with an average grain size of less than 100 nm has been successfully prepared on a Ti–6Al–4V sheet surface by sliding friction treatment (SFT). The electrochemical corrosion/passive behavior and mechanical properties of an NG Ti–6Al–4V sheet were examined in this study. A bi-layer passive film that consisted of an outer TiO₂-rich layer and an inner Al₂O₃-rich layer was formed on either an NG or coarse-grained (CG) surface. The improved corrosion was mainly caused by the enhanced stability and thickness of the passive layer. Tensile experiments were carried out to evaluate the mechanical properties at ambient temperature. The NG Ti–6Al–4V sample exhibited the high yield strength (956 MPa) with a moderate elongation of 8%. These superior comprehensive properties demonstrated its potential as a biomedical material.

Rotation-Assisted Hydrothermal Synthesis of Thermally Stable Multiwalled Titanate Nanotubes and Their Application to Selective Catalytic Reduction of NO with NH3

Titanate nanotubes are widely applied in various fields, including photocatalysts and electronic devices, but their weak thermal stability limits their application for catalyst support. Here, we found that titanate nanotubes with a thick multiwalled structure of 15 layers or more can be prepared by using rotation-assisted hydrothermal synthesis. The porous structure of conventional nanotubes synthesized without rotation collapsed easily after thermal treatment, whereas the nanotubes having a thick multiwalled structure retained their pore structure and the specific surface area (∼300 m²/g) even after calcination at 400 °C in air. Systematic variation of rotation speed suggested that rotation in the synthesis process accelerated the stacking of layered titanate nanosheets, which are known to be intermediates of nanotubes. Thus, the rapid assembly of titanate nanosheets facilitated by rotation led to the formation of nanotubes with a multiwalled structure. Overly fast rotation, however, caused excessive stacking and created a thicker structure that cannot be easily wrapped into nanotubes. Therefore, it is essential to maintain the optimum rotation speed to obtain both the nanotube morphology and the thick multiwalled structure. Vanadium-tungsten-oxide catalyst supported on the multiwalled titanate nanotubes was used in NH₃-selective catalytic reduction, which showed stable NO _x reduction performance with high selectivity to N₂, which may originate from the suppressed sintering of VO _x on multiwalled nanotubes. This study demonstrates that the morphology of nanotubes can be tuned by controlling the degree of interaction supplied by external forces.

Sorption pH dependance of strontium/calcium by sodium nonatitanate

Sodium nonatitanate powder is a layered material containing some potential exchangeable sodium ions between layers. In this work, sorption mechanism of this material has been studied and modeled at the solid-liquid interface. In particular, the ion-exchange mechanism is up to now not entirely known and especially the role of the pH on sorption properties. To investigate this latter, the solid is first equilibrated with inert acidic and base (nitric acid and triethylamine) for which the co-ions nitrate and triethylammonium do not penetrate the solid. The exchange between proton or divalent ions (strontium or calcium), and the sodium initially located in the sodium nonatitanate, is characterized through capillary ionic chromatography and conductivity experiments. To understand and explain the sorption properties, we modeled the equilibrium constant of different exchange reactions as a function of the solution pH. The equilibrium constants of the strontium/sodium and the calcium/sodium exchange have been obtained. We have shown the important role of the pH on the sorption rate of the strontium and moreover the hydrolysis rate of the sodium nonatitanate is calculated. We found that one eighth of sodium is spontaneously hydrolysed in aqueous phase whereas seven-eighths are exchanged by different divalent cations (strontium or calcium). Strontium and calcium exhibit similar exchange curves and competition with the proton adsorbed is modeled with global equilibrium constant. The prediction is in agreement with the conductivity experiments and the global extraction isotherms.

Recent developments in nanostructured inorganic materials for sorption of cesium and strontium: Synthesis and shaping, sorption capacity, mechanisms, and selectivity-A review

Liquid wastes containing non-ferrous heavy metal ions and some radionuclides, ¹³⁷Cs and ⁹⁰Sr in particular, represent one of the most dangerous sources of environmental contamination. The remediation of wastewater containing such pollutants continue to be among the biggest challenges of Sustainable Development and Environmental Safety. Sorption-based technologies have proven their efficiency also in reducing the radionuclide content in aqueous streams to low-level residual activity, with the concomitant decrease in the amount of ultimate solid waste generated. Although sorption of cesium and strontium by resins, clays, and zeolites has been investigated intensively and even used in real applications, there is still considerable scope for improvement in terms of retention capacity and selectivity. Recent progress in design and preparation of nanostructured inorganic materials has attracted growing interest based on the potential for improving the retention performance when coupling such functionalities as ion exchange capacity, structural flexibility that may result in steric retention effects, as well as the propensity to interact specifically with the target metal cations. Titanate, vanadate, and tungsten based materials, manganese oxides, hexacyanoferrates, metal sulfides, ammonium molybdophosphates, or hydroxyapatite, characterized by various structures and morphologies, are reviewed with the emphasis being put on synthesis and shaping of such materials, their structure in relationship with the capacity and selectivity of trapping cesium and strontium from either single or multi-component aqueous solutions, as well as the possible retention mechanism. The potential candidates for remediation uses are selected with regard to their sorption capacity and distribution coefficient towards target cations, and also the pH window for an optimum cation capture.

Structure of aqueous NaOH solutions: insights from neural-network-based molecular dynamics simulations

Sodium hydroxide, NaOH, is one of the most widely-used chemical reagents, but the structural properties of its aqueous solutions have only sparingly been characterized. Here, we automatically classify the cation coordination polyhedra obtained from molecular dynamics simulations. We find that, for example, with increasing concentration, octahedral coordination geometries become less favored, while the opposite is true for the trigonal prism. At high concentrations, the coordination polyhedra frequently deviate considerably from "ideal" polyhedra, because of an increased extent of interligand hydrogen-bonding, in which hydrogen bonds between two ligands, either OH₂ or OH^-, around the same Na⁺ are formed. In saturated solutions, with concentrations of about 19 mol L^-1, ligands are frequently shared between multiple Na⁺ ions as a result of the deficiency of solvent molecules. This results in more complex structural patterns involving certain "characteristic" polyhedron connectivities, such as octahedra sharing ligands with capped trigonal prisms, and tetrahedra sharing ligands with trigonal bipyramids. The simulations were performed using a density-functional-theory-based reactive high-dimensional neural network potential, that was extensively validated against available neutron and X-ray diffraction data from the literature.

Oxidized Ti3C2MXene nanosheets for dye-sensitized solar cells

Porous TiO₂electrodes were prepared by oxidizing Ti₃C₂nanosheets at different temperatures in air and were tested in dye-sensitized solar cells.

One-dimensional zirconium-doped titanate nanostructures for rapid and capacitive removal of multiple heavy metal ions from water

A novel, one-dimensional zirconium-doped titanate with a porous core and a textured surface of ultrafine nanofibers, exhibiting superior efficiency for rapid and simultaneous removal of multiple heavy metal ions.

Solution-phase synthesis of transition metal oxide nanocrystals: Morphologies, formulae, and mechanisms

In this review, we provide a broad overview of solution-phase synthesis of transition metal oxide nanocrystals (NCs), including a substantial catalog of published methods, and a unifying classification and discussion. Prevalent subcategories of solution-phase synthesis are delineated and general features are summarized. The diverse morphologies achievable by solution-phase synthesis are defined and exemplified. This is followed by sequential consideration of the solution-phase synthesis of first-row transition metal oxides. The common oxides of Ti, V, Mn, Fe, Co, Ni, Cu, and Zn are introduced; major crystal lattices are presented and illustrated; representative examples are explained; and numerous synthesis formulae are tabulated. Following this presentation of experimental studies, we present an introduction to theories of NC nucleation and growth. Various models of NC nucleation and growth are addressed, and important concepts determining the growth and structure of colloidal NCs are explained. Overall, this review provides an entry into systematic understanding of solution-phase synthesis of nanocrystals, with a reasonably comprehensive survey of results for the important category of transition metal oxide NCs.

Nanojoint Formation between Ceramic Titanate Nanowires and Spot Melting of Metal Nanowires with Electron Beam

Construction of nanoarchitectures requires techniques like joint formation and trimming. For ceramic materials, however, it is extremely difficult to form nanojoints by conventional methods like merging. In this work, we demonstrate that ceramic titanate nanowires (NWs) can be joined by spot melting under electron beam (e-beam) irradiation (EBI). The irradiation fuses the contacted spot of titanate NWs yielding an intact nanojoint. Nanojoints with different morphologies can be produced. The joint structures consist of titanium dioxide (TiO₂) rutile, anatase, and titanate phases in the direction away from the e-beam melting spot. The titanate binds to anatase via a crystallographic matching coherent interface (the oxygen atoms at the interface are shared by the two phases) and the anatase solidly binds to the rutile joint. The resulting rutile joint is stable at high temperatures. Additionally, it is demonstrated that the heat production from EBI treated rutile can be utilized to break metal NWs (Ag, Cu, and Ni) apart by spot melting. The required e-beam intensity is considerably mild (75 pA/cm²) which allows visual access and control over the NW melting. Direct melting of Ag and Cu is not applicable under EBI due to their high thermal conductivity even with high current density (500 pA/cm²). Our findings reveal that ceramic nanojoint formation and spot melting at nanoscale are applicable if the properties of nanomaterials are understood and properly utilized.

Current status and future challenges in ionic liquids, functionalized ionic liquids and deep eutectic solvent-mediated synthesis of nanostructured TiO2: a review

This review is on current advancements in IL-mediated synthesis of TiO₂, and the potential for future research in this area.

Same titanium glycolate precursor but different products: successful synthesis of twinned anatase TiO2 nanocrystals with excellent solar photocatalytic hydrogen evolution capability

Exploiting a synthesis protocol to tailor TiO₂ with a unique morphology and crystal phase has received considerable interest in the energy and environmental fields.

Coherent-Interface-Assembled Ag2O-Anchored Nanofibrillated Cellulose Porous Aerogels for Radioactive Iodine Capture

Nanofibrillated cellulose (NFC) has received increasing attention in science and technology because of not only the availability of large amounts of cellulose in nature but also its unique structural and physical features. These high-aspect-ratio nanofibers have potential applications in water remediation and as a reinforcing scaffold in composites, coatings, and porous materials because of their fascinating properties. In this work, highly porous NFC aerogels were prepared based on tert-butanol freeze-drying of ultrasonically isolated bamboo NFC with 20-80 nm diameters. Then nonagglomerated 2-20-nm-diameter silver oxide (Ag₂O) nanoparticles (NPs) were grown firmly onto the NFC scaffold with a high loading content of ∼500 wt % to fabricate Ag₂O@NFC organic-inorganic composite aerogels (Ag₂O@NFC). For the first time, the coherent interface and interaction mechanism between the cellulose I_β nanofiber and Ag₂O NPs are explored by high-resolution transmission electron microscopy and 3D electron tomography. Specifically, a strong hydrogen between Ag₂O and NFC makes them grow together firmly along a coherent interface, where good lattice matching between specific crystal planes of Ag₂O and NFC results in very small interfacial straining. The resulting Ag₂O@NFC aerogels take full advantage of the properties of the 3D organic aerogel framework and inorganic NPs, such as large surface area, interconnected porous structures, and supreme mechanical properties. They open up a wide horizon for functional practical usage, for example, as a flexible superefficient adsorbent to capture I^- ions from contaminated water and trap I₂ vapor for safe disposal, as presented in this work. The viable binding mode between many types of inorganic NPs and organic NFC established here highlights new ways to investigate cellulose-based functional nanocomposites.

Multifunctional flexible free-standing titanate nanobelt membranes as efficient sorbents for the removal of radioactive (90)Sr(2+) and (137)Cs(+) ions and oils

For the increasing attention focused on saving endangered environments, there is a growing need for developing membrane materials able to perform complex functions such as removing radioactive pollutants and oil spills from water. A major challenge is the scalable fabrication of membranes with good mechanical and thermal stability, superior resistance to radiation, and excellent recyclability. In this study, we constructed a multifunctional flexible free-standing sodium titanate nanobelt (Na-TNB) membrane that was assembled as advanced radiation-tainted water treatment and oil uptake. We compared the adsorption behavior of ¹³⁷Cs⁺ and ⁹⁰Sr²⁺ on Na-TNB membranes under various environmental conditions. The maximum adsorption coefficient value (K_d) for Sr²⁺ reaches 10⁷ mL g⁻¹. The structural collapse of the exchange materials were confirmed by XRD, FTIR and XPS spectroscopy as well as Raman analysis. The adsorption mechanism of Na-TNB membrane is clarified by forming a stable solid with the radioactive cations permanently trapped inside. Besides, the engineered multilayer membrane is exceptionally capable in selectively and rapidly adsorbing oils up to 23 times the adsorbent weight when coated with a thin layer of hydrophobic molecules. This multifunctional membrane has exceptional potential as a suitable material for next generation water treatment and separation technologies.

Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

Semiconductor TiO₂ photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH₄N₂S) modified anatase TiO₂ nanorods were fabricated by calcination of the mixture of TiO₂ nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO₂ nanorods. With increasing the weight ratio of thiourea to TiO₂ (R) from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO₂ nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B) and Rhodamine B (RhB) dyes under visible light irradiation (λ > 420 nm). The increased visible-light photocatalytic activity of the prepared N-doped TiO₂ nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

Efficient removal of U(vi) from aqueous solutions by polyaniline/hydrogen-titanate nanobelt composites

The organic–inorganic hybrid material of polyaniline/hydrogen-titanate nanobelt (PANI/H-TNB) composites was fabricated as a potential adsorbent to remove U(vi) from wastewater.

A core–shell structure of polyaniline coated protonic titanate nanobelt composites for both Cr(vi) and humic acid removal

The current methods for chromium and natural organic matter decontamination from wastewater present limitations, such as high cost, poor reproducibility, and detrimental environmental effects as well as by secondary waste.

Hierarchical TiO2–B/anatase core/shell nanowire arrays for efficient dye-sensitized solar cells

Hierarchical TiO₂–B/anatase core/shell heterojunction nanowire arrays on a titanium plate substrate are synthesized and used as novel photoanode materials for DSSCs.

Single-Step Synthesis of SnS₂ Nanosheet-Decorated TiO₂ Anatase Nanofibers as Efficient Photocatalysts for the Degradation of Gas-Phase Diethylsulfide

We report on a facile one-step soft hydrothermal process for synthesizing 1D anatase TiO2 nanofibers decorated with ultrathin SnS2 nanosheets. H-titanate nanofibers were used as preshaped Ti precursor. Under controlled conditions, the H-titanate structure was transformed into anatase maintaining the fibril morphology, while at the same time SnS2 nanosheets were grown in situ on the surface of the nanofibers. The successful formation of SnS2 nanosheets on the TiO2 nanofibers was confirmed by high-resolution TEM, and together with XPS spectroscopy, the tight interface formed between the SnS2 and the anatase TiO2 nanofibers was verified. The 1D SnS2/TiO2 hierarchical nanostructures with semiconductor heterojunction were proven to be very efficient under artificial solar irradiation in the photocatalytic degradation of gaseous diethylsulfide as simulant for live yperite chemical warfare agent as well as model substrate for malodorous organosulfide volatile organic compounds. SnS2 did not operate as a visible light sensitizer for TiO2 but rather as an oxidizing agent and charge-carrier separator. The semiconductor ratio in the heterostructure controlled the photoactivity. Samples with no or high content of SnS2 were less active than those with moderate SnS2 content. Enhanced reactivity was ascribed to an efficient separation of the photogenerated charge carriers driven by the differences in band edge positions and favored by the tight interface within the coupled heterostructure.

Selective synthesis of TiO2 single nanocrystals and titanate nanotubes: a controllable atomic arrangement approach via NH4TiOF3 mesocrystals

Nanostructured titania and titanate have been considered as very important materials used in photocatalysis, photovoltaics, gas sensing and other electronic industries. In principle, their common structural feature is that the precursor phase involving TiO6 octahedra or similar building units may be converted to any of the nanostructured titania and titanate forms in a controllable way. Based on the atomic arrangement of ionic liquid-mediated NH4TiOF3 mesocrystals, TiO2 nanocrystals and titanate nanotubes were selectively obtained in H3BO3 and NaOH media, respectively, by using a simple hydrothermal method. Interestingly, the titanate nanotubes were successfully formed by extraction of NH4(+) and F from NH4TiOF3 in a milder alkaline environment as low as 1 M NaOH, rather than conventional treatment of TiO2 in 10 M NaOH. The as-prepared TiO2 nanocrystals with exposed {001} facets exhibit a high photocatalytic activity and sedimentation rate as compared to commercial TiO2. Upon further doping or ion-exchange, the newly prepared TiO2 nanocrystals will show potential applications in the environment.