Charged Titanium Research Articles

Significance of non-DLVO interactions on the co-transport of levofloxacin and titanium dioxide nanoparticles in porous media

With the application of engineered nanomaterials and antibiotics in the fields of medicine, aerospace, new energy and agriculture, the associated contamination is detected widely in soil-groundwater systems. It is of great scientific and practical significance to deeply explore the environmental interface process between nanoparticles and antibiotics for the scientific assessment of environmental fate and ecological environmental risks, as well as the development of new composite pollution control technologies. In this study, the co-transport behaviors of positively charged titanium dioxide nanoparticles (TiO2-NPs) and negatively charged levofloxacin (LEV) in quartz sand (QS) are investigated in this study. The results show that TiO2-NPs hardly flow out when transported alone in the column because of its positive charge, which creates a strong attraction with the negatively charged quartz sand on the surface. When TiO2-NPs co-migrate with LEV in porous media, the presence of LEV promotes the transport of TiO2-NPs, while the presence of TiO2-NPs inhibits LEV transport. Non-XDLVO interactions based on molecular dynamics (MD) simulations can help explain the observed promotion and inhibition phenomena as well as the correlation between TiO2-NPs and LEV. The results indicate that TiO2-LEV complexes or aggregates can be formed during the co-transportation process of TiO2-NPs and LEV in porous media. As flow velocity increases from 0.204 cm min−1 to 1.630 cm min−1, both the transport capacities of TiO2-NPs and LEV are enhanced significantly. Under the condition of high citric acid (CA) concentration (15 mmol L−1), the transport capacity of TiO2-NPs is slightly inhibited, while the transport capacity of LEV is enhanced. This study provides new insights into the transport of nanometallic oxides and antibiotics in porous media, which suggests that non-XDLVO interactions should be considered together when assessing the environmental risks and fate of nanometallic oxides and antibiotics in soil-groundwater systems.

Tailoring Built-In Electric Field in a Self-Assembled Zeolitic Imidazolate Framework/MXene Nanocomposites for Microwave Absorption.

Heterointerface engineering, which plays a pivotal role in developing advanced microwave-absorbing materials, is employed to design zeolitic imidazolate framework (ZIF)-MXene nanocomposites. The ZIF-MXene composites are prepared by electrostatic self-assembly of negatively charged titanium carbide MXene flakes and positively charged Co-containing ZIF nanomaterials. This approach effectively creates abundant Mott-Schottky heterointerfaces exhibiting a robust built-in electric field (BIEF) effect, as evidenced by experimental and theoretical analyses, leading to a notable attenuation of electromagnetic energy. Systematic manipulation of the BIEF-exhibiting heterointerface, achieved through topological modulation of the ZIF, proficiently alters charge separation, facilitates electron migration, and ultimately enhances polarization relaxation loss, resulting in exceptional electromagnetic wave absorption performance (reflection loss RLmin = -47.35 dB and effective absorption bandwidth fE = 6.32 GHz). The present study demonstrates an innovative model system for elucidating the interfacial polarization mechanisms and pioneers a novel approach to developing functional materials with electromagnetic characteristics through spatial charge engineering.

Adsorption of a water molecule on the surface of neutral and charged titanium clusters: Tin-H2O, Tin+1-H2O, Tin-1-H2O, n ≤ 9

Adsorption of a water molecule on the surface of neutral and charged titanium, Tin0, ±1 H2O, n ≤ 9, clusters was studied in this work using density functional theory, BPW91-D2, all-electron calculations. Water adsorption is crucial for understanding the nascent solvation of Tin and H-O bond activation. Computed Tin0,±1 ground states, GS, allow a characterization of the structural, electronic, and energetic properties. Compact forms appear for the Tin0,±1, n ≤ 9 GS, and the estimated ionization energies (IE), electron affinities (EA) and binding energies (D0) follow the trends of available experimental results. The most stable clusters are Ti4+1, Ti50, -1, Ti70, ±1, and Ti90, ± 1, being in accord with the measured D0 for the cations. Overall, the cations show larger D0 that neutral and anions: D0(Tin+) > D0 (Tin) > D0(Tin-). Further, the IE are reduced by water adsorption on the Tin clusters, this being due to delocalization effects, through the network of the Ti–Ti and Ti–O bonds, of the most external valence electrons of Tin-H2O. For Tin+H2O, the lowest D0 occur at n = 4, 7, and 9, with maximums at n = 5 and 8, the highest D0 is for n = 1; being different from those of bare Tin+. Metal-oxygen Ti-O bond and Ti-H bond interactions account for the adsorption of water on Tin0,±1, which occurs on a metal atom of a triangular Ti3 face. In the Ti-O and Ti-H bond pattern, the metal atom is roughly placed in between the O and H atoms, originating agostic bonds, which produce H-O bond activation, being larger in the Tin––H2O anions. Thus, the titanium clusters may show catalytic behavior in their interaction with water molecules.

Breaking the continuous hydride network in hydrogen-charged pure titanium to repair hydride–induced performance degradation by applying a pulsed electric current

Titanium readily reacts with hydrogen to form hydrides, which greatly deteriorates their mechanical properties. In particular, the continuous hydride network provides a path for crack initiation and propagation. In this study, the hydrogen–charged pure titanium with continuous hydride network were treated by electropulsing treatment and traditional heat treatment. It was found that the elongation of the hydrogen–charged pure titanium were effectively repaired after the electropulsing treatment, while the heat treatment failed. The recovery of elongation of the hydrogen–charged pure titanium can be attributed to the disintegration of the continuous hydride network and the decrease of hydrogen content after the electropulsing treatment. Due to the different electrical properties of the hydrides and the Ti-matrix, the current in hydrogen-charged pure titanium is not uniformly distributed, resulting in the decomposition of the continuous hydride network at lower than conventional tempering temperatures. This particular method can not only be used for the repair of hydride–induced embrittlement, but also can be extended to the optimization of thermo–hydrogen treatment of titanium alloys and the rapid hydrogen release of metal–hydride hydrogen storage materials.

Design principles for the fabrication of high-performance cathode-electrolyte interphase for Li-ion batteries

Cathode-electrolyte interphase (CEI) is vital to the safety and lifespan of high-voltage cathode materials. However, the CEI formation mechanism in Li-ion batteries remains unclear. In a recent Matter article, Zhang et al. report on a real-time formation mechanism. Here, we discuss challenges and propose design principles in the fabrication of high performance CEI. Cathode-electrolyte interphase (CEI) is vital to the safety and lifespan of high-voltage cathode materials. However, the CEI formation mechanism in Li-ion batteries remains unclear. In a recent Matter article, Zhang et al. report on a real-time formation mechanism. Here, we discuss challenges and propose design principles in the fabrication of high performance CEI. In situ TEM visualization of LiF nanosheet formation on the cathode-electrolyte interphase (CEI) in liquid-electrolyte lithium-ion batteriesZhang et al.MatterFebruary 7, 2022In BriefThe formation behaviors of LiF nanocrystals have been studied on anodes in Li-ion batteries; there is no research work reporting LiF crystal growth on cathodes. Here, we report a real-time LiF crystal formation on positively charged titanium (Ti) electrodes in an electrochemical liquid cell with 150-nm-thick Li hexafluorophosphate (LiPF6)/propylene carbonate (PC) liquid electrolyte loaded. The LiF nanocrystals show two-dimensional (2D) morphologies on the electrode surface, which can serve as a cathode electrolyte interface (CEI). Full-Text PDF

In situ TEM visualization of LiF nanosheet formation on the cathode-electrolyte interphase (CEI) in liquid-electrolyte lithium-ion batteries

<h2>Summary</h2> The formation behaviors of LiF nanocrystals have been studied on anodes in Li-ion batteries; there is no research work reporting LiF crystal growth on cathodes. Here, we report a real-time LiF crystal formation on positively charged titanium (Ti) electrodes in an electrochemical liquid cell with 150-nm-thick Li hexafluorophosphate (LiPF₆)/propylene carbonate (PC) liquid electrolyte loaded. The LiF nanocrystals show two-dimensional (2D) morphologies on the electrode surface, which can serve as a cathode electrolyte interface (CEI). Furthermore, the merging of LiF nanosheets was also observed, which may underlie the self-healing ability of LiF-based CEIs. Theoretical modeling indicates that there are two types of LiF formation paths on positive voltage-biased Ti electrodes. This work shows the remarkable morphing mobility and self-healing ability of LiF nanosheets and sheds light on strategies of modulating LiF nanocrystals and cathode surface chemistry for improving battery performance and cycle life.

Deicing coatings go transparent

A new transparent deicing coating that can also clean itself could be a boon for solar panels, windows, and windshields ( Adv. Mater. 2021, DOI: 10.1002/adma.202108232 ). Preventing ice buildup on car windshields and aircraft today requires spraying the surfaces with glycol-based antifreeze or deicing fluids. For a simpler, more ecofriendly alternative , researchers are developing anti-ice coatings . These include superhydrophic or super-slippery surfaces that make water roll or slip off to delay freezing. Some groups have also made surfaces that heat up electrically or by absorbing sunlight to melt ice. Solar heating materials are the most economical and environmentally friendly method to combat ice, says Xiaokong Liu, a chemist at Jilin University. But light-absorbing materials generally tend to be dark. Liu and his colleagues made see-through coatings with MXenes , a class of 2D transition-metal carbides and nitrides. They deposited alternating nanosheets of the negatively charged titanium carbide

Interfacial thermal conductance between TiO2 nanoparticle and water: A molecular dynamics study

The interfacial thermal conductance (Kapitza conductance) between a TiO2 nanoparticle and water is investigated using transient non-equilibrium molecular dynamics. It is found that Kapitza conductance of TiO2 nanoparticles is one order of magnitude greater than other conventional nanoparticles such as gold, silver, silicon, platinum and also carbon nanotubes and graphene flakes. This difference can be explained by comparing the contribution of electrostatic interactions between the partially charged titanium and oxygen atoms and water atoms to the van der Waals interactions, which increases the cooling time by about 10 times. The effects of diameter and temperature of nanoparticle, surface wettability on the interfacial thermal conductance are also investigated. The results showed that by increasing the diameter of the nanoparticle from 4 to 9 nm, Kapitza conductance decreased slightly. Also, increasing the temperature of the heated nanoparticle from 400 K to 600 K led to thermal conductance enhancement. It has been found that increasing the coupling strength of Lennard-Jones (LJ) potential from 0.5 to 4 caused the increment of the Kapitza conductance about 20%. It is also shown that a continuum model which its input is provided by molecular dynamics can be a suitable approximation to describe the thermal relaxation of a nanoparticle in a liquid medium.

Electronic Transitions in Different Redox States of Trinuclear 5,6,11,12,17,18-Hexaazatrinaphthylene-Bridged Titanium Complexes: Spectroelectrochemistry and Quantum Chemistry.

Multinuclear transition metal complexes bridged by ligands with extended π‐electronic systems show a variety of complex electronic transitions and electron transfer reactions. While a systematic understanding of the photochemistry and electrochemistry has been attained for binuclear complexes, much less is known about trinuclear complexes such as hexaphenyl‐5,6,11,12,17,18‐hexaazatrinaphthylene‐tristitanocene [(Cp2Ti)3HATN(Ph)6]. The voltammogram of [(Cp2Ti)3HATN(Ph)6] shows six oxidation and three reduction waves. Solution spectra of [(Cp2Ti)3HATN(Ph)6] and of the electrochemically formed oxidation products show electronic transitions in the UV, visible and the NIR ranges. Density functional theory (DFT) and linear response time‐dependent DFT show that the three formally titanium(II) centers transfer an electron to the HATN ligand in the ground state. The optically excited transitions occur exclusively between ligand‐centered orbitals. The charged titanium centers only provide an electrostatic frame to the extended π‐electronic system. Complete active self‐consistent field (CASSCF) calculation on a structurally simplified model compound, which considers the multi‐reference character imposed by the three titanium centers, can provide an interpretation of the experimentally observed temperature‐dependent magnetic behavior of the different redox states of the title compound in full consistency with the interpretation of the electronic spectra.

Interfacing MXene flakes on fiber fabric as an ultrafast electron transport layer for high performance textile electrodes

Highly flexible and compliant textile-based electrodes are of considerable interest for the next generation of wearable devices. Engineering interconnected electron transport channels in the insulating textile substrate without any detriment to its intrinsic porous structure, flexibility, and stability generally is a great challenge in developing the high-performance devices. Herein, a strategy to prepare a highly conductive textile by electrostatic self-assembly between positively charged polyester fabric modified with polyethyleneimine (PEI) and negatively charged titanium carbide MXene flakes is presented. The densified, horizontally aligned MXene flakes are painted on the fabric fibers with a low mass loading of 0.8 ​mg ​cm−2. They not only form intergral layers of conductive skin, which can be easily charged/discharged at 10 ​V ​s−1, but also create numerous active sites for further introducing functional electrochemical materials due to the surface chemistry of the MXene. As a proof-of-concept application, the conductive textile is combined with conformally coated polypyrrole (PPy) and used as a supercapacitor electrode, which has demonstrated large areal capacitance, high rate performance, and outstanding cycling stability without compromising its mechanical endurance. These features suggest the great potential of the as-prepared electrodes and open up a new avenue for the development of a new generation of textile electrode for the smart textile industry.

Harvesting energy with MXene membranes

Capturing energy from salinity gradients—where fresh and salty water mix—requires expensive porous membranes that can control the flow of ions. Researchers now report that membranes made of 2-D metal carbide or metal nitride materials, known as MXenes, could work as well as conventional polymer membranes. MXene membranes should be easier and less expensive to make at large scales (ACS Nano 2019, DOI: 10.1021/acsnano.9b02579). Peng Wang and Husam N. Alshareef of King Abdullah University of Science and Technology and their colleagues made a reverse electrodialysis (RED) membrane out of stacked, ultrathin sheets of negatively charged titanium carbide. Cations can pass through the membrane’s maze-like channels, enabling it to separate positive and negative ions to create an electric potential. The researchers tested the membrane by putting a 1 mM potassium chloride solution on one side and a 1 M solution on the other. The power output densities of 21 W/m2 at room

Exfoliation and europium(III)-functionalization of α-titanium phosphate via propylamine intercalation: from multilayer assemblies to single nanosheets

Layered α-titanium phosphate intercalated with propylamine, Ti(HPO4)2·2C3H7NH2·H2O (α-TiPPr), has been synthesized by solid-vapour reaction and then exfoliated via a single-stage approach based on overnight stirring in aqueous medium. The obtained nanosheets were then functionalized using solid–liquid reaction with europium(III) nitrate aqueous solutions. The obtained materials were characterized by powder X-ray diffraction (PXRD), N2 adsorption–desorption isotherms at 77 K, scanning electron microscopy (SEM), transmission electron microscopy (TEM, SAED, STEM-EDX), atomic force microscopy (AFM) and photoluminescence spectroscopy (PL). The europium(III) sorption takes place via two distinct pathways, the first is the previously reported C3H7NH3+/[Eu(H2O)6]3+ ion-exchange process into the titanium–phosphate interlayer space of the multilayered α-TiPPr. The second pathway is the self-assembly of single-sheets which is provoked by electrostatic interactions between the negatively charged titanium–phosphate sheets and the Eu(III)-aqueous cations, leading to the formation of layered nanoparticles.

Enhanced osteoconductivity on electrically charged titanium implants treated by physicochemical surface modifications methods

Biomimetic design is a key tenet of orthopedic device technology, and in particular the development of responsive surfaces that promote ion exchange with interfacing tissues, facilitating the ionic events that occur naturally during bone repair, hold promise in orthopedic fixation strategies. Non-bioactive nanostructured titanium implants treated by shot-blasting and acid-etching (AE) induced higher bone implant contact (BIC=52% and 65%) compared to shot-blasted treated (SB) implants (BIC=46% and 47%) at weeks 4 and 8, respectively. However, bioactive charged implants produced by plasma (PL) or thermochemical (BIO) processes exhibited enhanced osteoconductivity through specific ionic surface-tissue exchange (PL, BIC= 69% and 77% and BIO, BIC= 85% and 87% at weeks 4 and 8 respectively). Furthermore, bioactive surfaces (PL and BIO) showed functional mechanical stability (resonance frequency analyses) as early as 4 weeks post implantation via increased total bone area (BAT=56% and 59%) ingrowth compared to SB (BAT=35%) and AE (BAT=35%) surfaces.

How water flips at charged titanium dioxide: an SFG-study on the water-TiO2 interface.

Photocatalytic splitting of water into hydrogen and oxygen by utilizing sunlight and a photocatalyst is a promising way of generating clean energy. Here, we report a molecular-level study on heavy water (D2O) interacting with TiO2 as a model photocatalyst. We employed the surface specific technique Sum-Frequency-Generation (SFG) spectroscopy to determine the nature of the hydrogen bonding environment and the orientation of interfacial water molecules using their OD-stretch vibrations as reporters. By examining solutions with various pD-values, we observe an intensity-minimum at around pD 5, corresponding to the balance of protonation and deprotonation of TiO2 (point of zero charge). The majority of water molecules' deuterium atoms point away from the interface when the pD is below 5, and point towards the surface when the pD is higher than 5, with strong hydrogen bonds towards the surface.

Interface engineering of $$\hbox {TiO}_{2}$$ TiO 2 @PANI nanostructures for efficient visible-light activation

Core–shell-structured $$\hbox {TiO}_{2}$$ @PANI composites were fabricated using negatively charged titanium glycolate (TG) precursor spheres, which were decorated using hydrochloric acid; subsequently, the uniform polyaniline (PANI) layer could be attached onto the surface of the polystyrene spheres by in situ chemical oxidative polymerization and finally, the resulting PANI-grafted TG were allowed to hydrolyse by treating the material with hot water. The TGs were transformed to porous $$\hbox {TiO}_{2}$$ , leading to the formation of core–shell $$\hbox {TiO}_{2}$$ @PANI composites. The resulting $$\hbox {TiO}_{2}$$ @PANI composite photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet–visible diffuse reflection spectroscopy and photoluminescence spectroscopy. Significantly, the $$\hbox {TiO}_{2}$$ @PANI composite photocatalysts exhibited dramatically enhanced photo-induced electron–hole separation efficiency, which was confirmed by the results of photocurrent measurements. PANI was dispersed uniformly over the porous $$\hbox {TiO}_{2}$$ surface with an intimate electronic contact on the interface to act cooperatively to achieve enhanced photocatalytic properties, indicating that core–shell $$\hbox {TiO}_{2}$$ @PANI composite photocatalysts could be promising candidate catalysts under visible-light irradiation. The mechanism of enhancing photocatalytic activity was proposed on the basis of the experimental results and estimated energy band positions.

Transition rate diagrams and excitation of titanium in a glow discharge in argon and neon

Emission spectra of titanium in a Grimm-type glow discharge in argon and neon were studied using the formalism of transition rate diagrams. Ti I spectra in argon and neon discharges are similar, without signs of selective excitation, and populations of Ti I levels exhibit a decreasing trend as function of energy, except for some scatter. A major excitation process of Ti II in argon discharge is charge transfer from argon ions to neutral titanium. In neon discharge, a strong selective excitation was observed of Ti II levels at ≈13.3–13.4 eV relative to the Ti I ground state. It was attributed to charge transfer from doubly charged titanium ions to neutral titanium, while the Ti++ ions are produced by charge transfer and ionization of neutral titanium by neon ions. Cascade excitation is important for Ti II levels up to an energy of ≈13 eV relative to the Ti I ground state, both in argon and neon discharges.

First measurements of the temporal evolution of the plasma density in HiPIMS discharges using THz time domain spectroscopy

In this paper, the novel technique of THz time domain spectroscopy has been applied to obtain time-resolved measurements of the plasma density in the active zone of a HiPIMS discharge with a titanium target. The obtained peak values are in the range of 1012–1013 cm−3 for discharge current densities of 1–4 A cm−2 at 0.5 and 2 Pa argon pressure. The measured densities show good correlation with the discharge current and voltage and the intensity of various atomic and ionic lines. The well known phases of the discharge have been identified and related to the variation of the electron density. The measurement results show that the plasma density remains nearly constant during the runaway/self-sputtering phase. Based on that, it is conjectured that singly charged titanium ions are the dominant ion species during this phase.

Effect of magnetic field on spoke behaviour in HiPIMS plasma

The objective of this paper is to study the effect of magnetic field strength on spoke behaviour in a high power impulse magnetron sputtering discharge. In three magnetic field configurations, a broad range of experimental conditions was investigated by high-speed camera imaging. The dual image feature of the employed camera enabled us to determine the shape and spoke mode number, as well as the velocity of the spokes. Five distinct spoke shapes were detected. For each magnetic field, a map was created relating the occurrence of the spoke shape with the discharge conditions. Similarly, the spoke mode number, as well as the spoke velocity, was found to be strongly dependent on the discharge conditions. Based on the optical emission results, it was proposed that the trailing edge of the triangular spoke is related to the production of secondary electrons created by argon ions on the spoke edges, while in the case of a round spoke shape, the secondary electrons are mainly created by multiple charged titanium ions in the centre of the spoke.

Three-dimensional titanium dioxide/graphene hybrids with improved performance for photocatalysis and energy storage

A series of three-dimensional (3-D) TiO2/graphene (TiO2/GR) hybrids with different TiO2 weight ratios were prepared using a self-assembly approach followed by the gaseous reduction in a hydrothermal system. The method was based on the electrostatic attraction between the positively charged titanium glycolate precursor and negatively charged graphene oxide in an aqueous medium without any surfactant or template. The structure, morphology, physical and optical properties of the as-synthesized hybrids were characterized, and the results showed that TiO2 spheres were homogeneously confined within the 3-D networks of graphene, and acted as pillars to effectively separate the graphene sheets from each other. By optimizing the ratio of TiO2 in the hybrids, the material was identified as an excellent photocatalyst to remove organic compound in water with high degradation efficiency. Additionally, TiO2/GR hybrids delivered high specific capacity, enhanced rate capability and excellent cyclic stability when used as a freestanding electrode for lithium ion batteries.

UV protective PET nanocomposites by a layer-by-layer deposition of TiO2 nanoparticles

The oppositely charged titanium dioxide (TiO2) nanoparticles were deposited on the surface of poly(ethylene terephthalate) (PET) substrates by a layer-by-layer (LBL) assembly method. The PET films were pretreated by concentrated alkaline solution so as to introduce functional groups to attract TiO2 nanoparticles onto the surface. The oppositely charged TiO2 nanoparticles in the suspension can be controlled by adjusting the pH value. The multilayer buildup was monitored by UV-vis spectroscopy, which showed a linear increase of the film absorbance with the number of adsorbed TiO2 layers. Moreover, the morphology, structural, and chemical composition of the multilayer nanocomposite films were analyzed by scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results confirmed the presence and even distribution of TiO2 nanoparticles on the PET surfaces. The UV protective properties, thermal stability, and mechanical properties of the nanocomposite films were investigated. The values of ultraviolet protection factor (UPF) showed that the multilayer nanocomposite films exhibited high UV protective property. The TGA curves showed that TiO2 nanoparticles enhanced the thermal stability of nanocomposite films. Additionally, the nanocomposite films showed a lower tensile strength but a higher elongation than that of PET film.