Titanium (IV) Bis(ammonium Lactato) Dihydroxide Research Articles

Preparation of TiO2/WO3/C/N Composite Nanofibers by Electrospinning Using Precursors Soluble in Water and Their Photocatalytic Activity in Visible Light.

Extending the absorption range of TiO2 nanofibers to visible light is a great improvement of the photocatalytic property of TiO2. In this study, TiO2/WO3/C/N nanofibers were prepared by electrospinning using precursors soluble in water then annealing in argon. Titanium(IV) bis(ammonium lactato)dihydroxide (TiBALDH) and ammonium metatungstate (AMT) were used as the precursor for TiO2 and WO3 respectively. Different volume ratios of the precursors were added to a solution of PVP before electrospinning. The fibers were studied by XPS, SEM-EDX, TEM, FTIR, XRD, Raman spectroscopy and UV–VIS diffuse reflectance spectroscopy (DRS). The photocatalytic degradation of methylene blue by the fibers in visible light was investigated. The fibers had anatase TiO2 and monoclinic WO3. Based on UV–VIS DRS and Kubelka-Munk function the fibers could absorb visible light. Moreover, 100% TiBALDH had an indirect band gap of 2.9 eV, and the band gap decreased with increase in AMT, i.e., for 0% TiBALDH, band gap was 2.4 eV. The fibers degraded methylene blue dye in visible light, and 90% TiBALDH had the highest photocatalytic activity, i.e., it degraded 40% of the dye after 240 min.

Synthesis of TiO2/WO3 Composite Nanofibers by a Water-Based Electrospinning Process and Their Application in Photocatalysis.

TiO2/WO3 nanofibers were prepared in a one-step process by electrospinning. Titanium(IV) bis(ammonium lactato)dihydroxide (TiBALDH) and ammonium metatungstate (AMT) were used as water-soluble Ti and W precursors, respectively. Polyvinylpyrrolidone (PVP) and varying ratios of TiBALDH and AMT were dissolved in a mixture of H2O, EtOH and CH3COOH. The as-spun fibers were then heated in air at 1 °C min−1 until 600 °C to form TiO2/WO3 composite nanofibers. Fiber characterization was done using TG/DTA, SEM–EDX, FTIR, XRD, and Raman. The annealed composite nanofibers had a diameter range of 130–1940 nm, and the results showed a growth in the fiber diameter with an increasing amount of WO3. The photocatalytic property of the fibers was also checked for methyl orange bleaching in visible and UV light. In visible light, the photocatalytic activity increased with an increase in the ratio of AMT, while 50% TiBALDH composite fibers showed the highest activity among the as-prepared fibers in UV light.

Synthesis of TiO2 nanofibers by electrospinning using water-soluble Ti-precursor

A new electrospinning process was developed for preparing TiO2 nanofibers using a water-soluble Ti-precursor, [bis(kappa1O-hydroxo)(bis(kappa2O,O′-lactato)titanium(IV)] commonly known as titanium(IV) bis (ammonium lactato) dihydroxide (TiBALDH). The importance of the study is justified by the fact that Ti-precursors used for electrospinning, sol–gel, hydrothermal and other fiber synthesis processes are mostly non-water soluble. Accordingly, anatase TiO2 nanofibers of diameter between 20 and 140 nm were synthesized by electrospinning and annealing. Polyvinylpyrrolidone (PVP) and different concentrations of TiBALDH were dissolved in a mixture of water, ethyl alcohol and acetic acid to optimize the electrospinning conditions. The thermal decomposition and fragmentation of PVP, TiBALDH and the fibers with 50% mass fraction of TiBALDH were studied by TGA-MS measurements. The fibers were then annealed at 1 °C min−1 until 600 °C. The TiO2 fibers were characterized using SEM–EDX, FTIR and XRD

Development of Titania-Integrated Silica Cell Walls of the Titanium-Resistant Diatom, Fistulifera solaris.

We report the biological synthesis of titania that is integrated into the silica-based cell walls of a titanium-resistant diatom, Fistulifera solaris. Titania is deposited across the diatom cell walls by simply incubating F. solaris in a culture medium containing a high concentration (2 mM) of a water-soluble organo-titanium compound, titanium(IV) bis(ammonium lactato) dihydroxide (TiBALDH) that would otherwise inhibit the growth of other diatom species. Furthermore, we genetically engineered the interfaces of the diatom cell walls with a titanium-associated peptide, which subsequently increased the Ti/Si atomic ratio by more than 50% (i.e., from 6.2 ± 0.2% to 9.7 ± 0.5%, as identified by inductively coupled plasma-atomic emission spectrometry). The titanium content on the F. solaris silica cell walls is one of the highest reported to date, and comparable to that of chemically synthesized TiO2-silica composites. Subsequent thermal annealing at 500 °C in air converted the cellwall-bound titania to nanocrystalline anatase TiO2, a highly photocatalytically active phase. We propose that incubation of the titanium-resistant F. solaris with TiBALDH as demonstrated in this study could be a promising bioprocess toward the scalable synthesis of TiO2. In addition, the genetic engineering we used to modulate the surface properties of diatom silica cell walls could be extended to synthesize controlled nanomaterials for multiple applications including bioremediation, water purification, and energy conversion/storage.

Synthesis of novel laccase-biotitania biocatalysts for malachite green decolorization

Biomimetic mineralization has emerged as a novel tool for generating excellent supports for enzyme stabilization. In this work, protamine was used to induce titanium (IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) into titania nanoparticles. This biomimetic titanification process was adopted for laccase immobilization. Laccase-biotitania biocatalyst was prepared and the effect of different parameters (buffer solution, titania precursor concentration, protamine concentration, and enzyme loading) on the encapsulation efficiency and recovery of laccase were evaluated. Compared with free laccase, the thermal and pH stability of immobilized laccase were improved significantly. In addition, laccase loaded on titania was effective at enhancing its storage stability. After seven consecutive cycles, the immobilized laccase still retained 51% of its original activity. Finally, laccase-biotitania biocatalysts showed good performance on decolorization of malachite green (MG), which can be attributed to an adsorption and degradation effect. The intermediates of the MG degradation were identified by gas chromatography-mass spectrometry (GC-MS) analysis, and the most probable degradation pathway was proposed. This study provides deeper understanding of the laccase-biotitania particles as a fast biocatalyst for MG decolorization.

Aerosol synthesis of trivalent titanium doped titania/carbon composite microspheres with superior sodium storage performance

Trivalent titanium doped titania/carbon (TiO2–x/C) composite microspheres have been prepared by a facile aerosol method (ultrasonic spray pyrolysis) using titanium (IV) bis(ammonium lactato)dihydroxide (TiBALDH) as the sole precursor. The obtained TiO2–x/C microspheres have particle sizes in the range of 400–1,000 nm. When evaluated as anode material for sodium-ion batteries (SIBs), they provide a high reversible capacity of 286 mA·h·g−1 with good cycling performance. A capacity of 249 mA·h·g−1 can be achieved after 180 cycles at 50 mA·g−1, which is more than three times higher than that of white TiO2 microspheres (77 mA·h·g−1). The superior sodium storage performance of these TiO2–x/C composite microspheres can be attributed to the simultaneous introduction of Ti3+ and oxygen vacancies, ultrafine grain size, as well as the conductive carbon matrix. This study provides a facile and effective approach for the production of TiO2–x/C nanocomposites with superior sodium storage performance.

Preparation of Dopamine/Titania Hybrid Nanoparticles through Biomimetic Mineralization and Titanium(IV)–Catecholate Coordination for Enzyme Immobilization

In this study, a facile approach is proposed to prepare dopamine/titania hybrid nanoparticles (DTHNPs), which are synthesized via directly blending titanium(IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) and dopamine aqueous solution. The amino group in dopamine is mainly in charge of inducing the hydrolysis and condensation of titanium precursor to form titania, and the catechol group in dopamine acts as an organic ligand to form titanium(IV)–catecholate coordination. These DTHNPs were characterized by tranmission electron miscroscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology of DTHNPs is changed from slightly cotton-shaped aggregates to monodisperse nanoparticles with the increase of dopamine concentration. As a model enzyme, catalase (CAT) is entrapped in the DTHNPs during the nanoparticle preparation process. Surprisingly, the entrapment efficiency of CAT can be high up to nearly 100%, and no enzyme leakage could be detected. Moreover, immobilized CAT possesses 90% the catalytic activity of free enzyme.

Optical and photocatalytic behaviours of nanoparticles in the Ti–Zn–O binary system

Continuous hydrothermal flow synthesis (CHFS) has been used as a rapid and clean, synthetic method to produce a range of crystalline nanoparticles in the Ti–Zn–O binary system. The nanopowders were prepared from aqueous solutions of titanium(IV) bis(ammonium lactato)dihydroxide (TIBALD) and hydrated zinc nitrate, respectively, using a CHFS reactor which uses superheated water (at 400 °C and 24.1 MPa) as a reagent and crystallizing medium. The resulting nanopowders were heat-treated at 850 °C for five hours in air to give photoactive semiconductor mixtures of rutile and zinc oxide and/or zinc titanates. The as-prepared powders and their corresponding heat-treated mixed phase photocatalysts were characterized using powder X-ray synchrotron diffraction, transmission electron microscopy, BET surface area measurement, X-ray photoelectron spectroscopy and UV-Vis spectrophotometry. Because of the interest for these materials in UVA and UVB attenuating materials, the UV-Vis profiles of the nanocomposites and solid solutions were studied. Photocatalytic activity of the samples towards the decolourisation of methylene blue dye was also assessed.

Titania microparticles using a facile microfluidic mass-transfer control method

Droplet microfluidics has found many applications in chemical reactions. In most of the studies, however, reactions are performed in droplet-based reactors either through introducing various reagent streams into a single droplet, or upon coalescence or merging of two droplets encapsulating different reagents. Here we introduce a facile microfluidic mass-transfer control approach for synthesizing titania microparticles using droplets as microreactors. Droplets of a water soluble and stable titania precursor aqueous solution, titanium(IV) bis(ammonium lactato)-dihydroxide (TiBALDH), were dispersed in an oil continuous phase containing a small amount of ethanol, which can precipitate TiBALDH and produce titania. Precipitation was initiated and controlled by the mass-transfer of ethanol from the continuous phase into the droplets. Titania particles with different degrees of compactness were formed and well encapsulated inside the droplets by varying the concentrations of TiBALDH in the droplet phase and ethanol in the continuous phase. This paper provides a new approach for synthesizing nanoparticles or microparticles in droplet microfluidics based on a mass-transfer control approach.

The interplay of peptide sequence and local structure in TiO2 biomineralization

Using cyclic constrained TiO2 binding peptides STB1 (CHKKPSKSC), RSTB1 (CHRRPSRSC) and linear peptide LSTB1 (AHKKPSKSA), it was shown that while affinity of the peptide to TiO2 is essential to enable TiO2 biomineralization, other factors such as biomineralization kinetics and peptide local structure need to be considered to predict biomineralization efficacy. Cyclic and linear TiO2 binding peptides show significantly different biomineralization activities. Cyclic STB1 and RSTB1 could induce TiO2 precipitation in the presence of titanium(IV)-bis-ammonium-lactato-dihydroxide (TiBALDH) precursor in water or tris buffer at pH 8. In contrast, linear LSTB1 was unable to mineralize TiO2 under the same experimental conditions despite its high affinity to TiO2 comparable with STB1 and/or RSTB1. LSTB1 being a flexible molecule could not render the stable condensation of TiBALDH precursor to form TiO2 particles. However, in the presence of phosphate buffer ions, the structure of LSTB1 is stabilized, leading to efficient condensation of TiBALDH and TiO2 particle formation. This study demonstrates that peptide-mediated TiO2 mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of mineralizing aider such as phosphate ions.

Amyloid Directed Synthesis of Titanium Dioxide Nanowires and Their Applications in Hybrid Photovoltaic Devices

AbstractThis paper reports β‐lactoglobulin amyloid protein fibrils directed synthesis of Titanium Dioxide (TiO2) hybrid nanowires. Protein fibrils act as templates to generate closely packed TiO2 nanoparticles on the surface of the fibrils using titanium (IV) bis (ammonium lactato) dihydroxide (TiBALDH) as precursor, resulting in the TiO2–coated amyloid hybrid nanowires. These amyloid fibrils also exhibit complexation with a luminescent water‐soluble semiconductive polythiophene (P3HT). TiO2 nanowires behave as electron acceptor while, P3HT as electron donor. In this way, amyloid‐TiO2 hybrid nanowires can serve in heterojunction photovoltaic devices. To demonstrate this, a photovoltaic active layer is prepared by spin coating the blended mixture of polythiophene‐coated fibrils and amyloid‐TiO2 hybrid nanowires. The current–voltage characteristics of these photovoltaic devices exhibit excellent fill factor of 0.53, photovoltaic current density of 3.97 mA·cm−2 and power conversion efficiency of 0.72%, highlighting a possible future role for amyloid‐based templates in donor–acceptor devices, organic electronics and hybrid solar cells.

Design of low-charge peptide sequences for high-yield formation of titaniananoparticles

A series of low-charge peptides were designed to explore the functionality of different amino acids in precipitating precursor titanium(IV) bis(ammonium lactato)-dihydroxide (TiBALDH), and to obtain insight into the mechanism of TiO2 biomineralization.

The improved stability of enzyme encapsulated in biomimetic titania particles

This study demonstrates a novel biomimetic approach for the entrapment of yeast alcohol dehydrogenase (YADH) within titania nanoparticles to improve its stability. Protamine was as the template and catalyst for the condensation of titanium (IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) into titania nanoparticles in which YADH was trapped. The as-prepared titania/protamine/YADH composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanism of YADH encapsulation was tentatively proposed from a series of experimental results. The preliminary investigation showed that encapsulated YADH could retain most of its initial activity. Compared to free YADH, encapsulated YADH exhibited significantly improved thermal, pH and recycling stability. After 5 weeks storage, no substantial loss of catalytic activity for encapsulated YADH was observed.

Biomimetic synthesis of titania nanoparticles induced by protamine

Protamine, a kind of cationic protein extracted from sperm nuclei, was employed for the first time in vitro to induce the formation of a titania/protamine nanoparticle composite from a water-stable titanium precursor, titanium(IV) bis(ammonium lactato) dihydroxide (Ti-BALDH). The resulting titania/protamine nanoparticle composite was extensively characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The titania/protamine nanoparticle composite was of amorphous structure, and exhibited a different morphology from those prepared by an alkali-catalyzed approach. The catalyzing and templating function of protamine involved in the synthesis of the nanoparticle composite is discussed, and a mechanism tentatively proposed. In addition, the effects of pH and temperature on the amount and size of as-prepared titania/protamine nanoparticle composite were systematically investigated.