Zirconium N-butoxide Research Articles

Up-scalable preparation of nano zirconium carbide powder in liquid polymeric precursor and its pyrolysis mechanism

Nano size ZrC powder was prepared by liquid polymeric precursor method. Zirconium n-butoxide (Zr(O n Bu) 4 ) and benzoylacetone (BA) were mixed directly with different molar ratios to synthesize transparent liquid zirconium carbide single-source precursors. The carbon content in the precursor could be changed by adding different amount of BA. X-ray pure ZrC was obtained when the molar ratio of BA/Zr(O n Bu) 4 was 4.6:1. The viscosity of the precursor was very low (<8 mPa s) without the addition of solvents. Zirconium carbide powders were fabricated by the pyrolysis at 800 °C in argon and subsequent heating at various temperatures in vacuum for carbothermal reduction reaction. The pyrolysis behavior, phase composition and transformation, and microstructure of the as-fabricated ZrC powders were analyzed. The gases of CH 4 , CO and CO 2 released due to decomposition and evaporation of the organic component and transformation from ZrO 2 to ZrC during pyrolysis resulted in total 60–70% mass loss. The average grain size of the synthesized X-ray pure ZrC powders was less than 30 nm. Meanwhile, the pyrolysis mechanism of nano zirconium carbide powder was deduced.

Effects of the number of benzene rings on the properties of single-source ZrC-based liquid precursors and nano zirconium carbide powders thereof

Effects of carbon source in single-source ZrC-based liquid precursors on the properties of the precursors and precursor-derived nano ZrC powders were investigated. The liquid precursors were prepared by directly blending and heating zirconium n-butoxide with either 2,4-pentanedione, benzoyl acetone or 1,3-diphenyl-1,3-propanedione additives which have the same chemical composition and structure except for the number of benzene rings (0, 1 and 2, respectively) in order to control the carbon content in the precursors. The ceramic yield of the precursor decreased as the number of benzene rings in the precursors increased. The stability of the precursors in air and the carbon content of the ceramic powder increased when using 1,3-diphenyl-1,3-propanedione additive. X-ray pure nano zirconium carbide powders with ultra-fine size (30 nm), isotropic shape and homogeneous particle size distribution were synthesized from the liquid precursors containing two benzene rings in the structure. Compared with ZrC powders derived from the precursors containing zero or one benzene ring, the powder from the precursor containing two benzene rings was finer and more homogeneous in size distribution.

Fabrication of magnetically recyclable ZrO2-TiO2/CoFe2O4 hollow core/shell photocatalysts: Improving photocatalytic efficiency under sunlight irradiation

TiO2 is an important material for photocatalytic oxidation to degrade organic pollutants, but its utilization under visible light is low, recovery is difficult, and stability is poor. We prepared ZrO2-TiO2/CoFe2O4 (Zr-Ti/Co) photocatalyst with hollow core-shell structure by sol-gel method and layer-by-layer self-assembly method with tetrabutyl titanate and Zirconium n-butoxide as main raw materials. The samples were characterized and analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), solid ultraviolet visible diffuse reflection (UV-Vis DRS), fluorescence (FL), ultraviolet visible absorption (UV), vibrating sample magnetometer (VSM). It is concluded that the TiO2 maintains a good anatase phase structure in the Zr-Ti-Co photocatalyst. Under UV light and sunlight, the degradation rate of the photocatalyst reached 96.1% and 99.7% for 60 min, respectively, for Rhodamine B (10mg/L) reaction system. And after repeated use for five times, it still showed better regeneration and reuse.

Preparation of highly porous ZrB2/ZrC/SiC composite monoliths using liquid precursors via direct drying process

We developed a simple liquid precursor method for the syntheses of porous ZrB2/ZrC/SiC composite monoliths. Furfuryl alcohol (FA), zirconium n-butoxide, tetraethyl orthosilicate and boric acid are used as the raw materials. By combining the polymerization of FA and gelation of inorganic sols, porous hybrid monoliths are prepared by direct drying the wet gels. The inorganic and organic polymers possibly form interpenetrated network which provides the robustness for the wet gel to withstand the severe changes during dessication. When heat-treated at 1600°C, hybrid gels are converted into porous ZrB2/ZrC/SiC monoliths. The microstructure of the ZrB2/ZrC/SiC monoliths can be easily tailored by controlling the synthesis conditions. The porosities of the ZrB2/ZrC/SiC monoliths can be tuned around 74.3–81.6%, while the average pore diameters can be tuned ranging from 1.0 to 8.5μm with pretty narrow distribution. The compressive strengths of such highly porous ceramics are in the range of 1.2–1.9MPa.

Electrospun zirconia-embedded carbon nanofibre for high-sensitive determination of methyl parathion

Carbon nanofibers embedded with ultrafine zirconia nanoparticles (ZrO2-CNFs) are fabricated via a new methodology. Polyvinylpyrrolidone (PVP) and polymethylmethacrylate (PMMA) binary polymers containing zirconium n-butoxide are first dissolved in dimethylformamide, and the resulting solution is electrospun and heat-treated. The tetragonal zirconia nanoparticles formed, with a size of 5±2nm in diameter, are uniformly distributed in the carbon nanofibres. Using Nafion as an additive, ZrO2-CNFs are drop-cast onto the glassy carbon electrode (ZrO2-CNF/GCE) and the modified electrode is then applied to detect methyl parathion (MP) using differential pulse voltammetry. Two linear relationships are found at the concentration ranges of 1×10−9–2×10−8g/L and 2×10−8–2×10−7g/L, with a detection limit of 3.4×10−10g/L (S/N>3). The electrospun-based ZrO2-CNF is a very promising coating material for electrochemical sensing of organophosphorus compounds.

Free-standing coating patterns fabricated by ultraviolet contact lithography using photosensitive sol-gel coatings

Photosensitive ZrO2-SiO2 hybrid sol-gel coatings containing large contents of chelating rings were prepared by using the zirconium n-butoxide (TBOZ) and methyltriethoxysilane (MTES) as hybrid precursors, and benzoylacetone (BZAC) as chelating agent. The change of ultraviolet (UV) absorption spectra, chemical composition, and optical properties of ZrO2-SiO2 hybrid sol-gel coatings were analyzed before and after UV exposure and calcination. The refractive index of the ZrO2-SiO2 hybrid gel coatings decreased from 1.673 to 1.561 with the increase of the molar content of MTES in precursors. The sol-gel coating patterns with the periods of 20.24 μm, 10.11 μm and 3.99 μm on the PAMS substrates were firstly obtained by using the photosensitive ZrO2-SiO2 hybrid sol-gel films as fundamental materials through a process of UV contact lithography with photo masks and etching with ethanol. Finally, the free-standing gel coating patterns supported by copper grids, with the period of 12.70 μm and line width of 4.93 μm, and the period of 14.20 μm and line width of 3.82 μm, were obtained by removing the PAMS thermal degradation sacrifice layer after being calcined at 330 °C. Micrometer-periodic free-standing gel coating patterns with different structure have potential applications in the laser physical experiments.

Degradable Polycaprolactone and Polylactide Homopolymer and Block Copolymer Brushes Prepared by Surface-Initiated Polymerization with Triazabicyclodecene and Zirconium Catalysts.

Surface-initiated ring-opening polymerization (SI-ROP) of polycaprolactone (PCL) and polylactide (PLA) polymer brushes with controlled degradation rates were prepared on oxide substrates. PCL brushes were polymerized from hydroxyl-terminated monolayers utilizing triazabicyclodecene (TBD) as the polymerization catalyst. A consistent brush thickness of 40 nm could be achieved with a reproducible unique crystalline morphology. The organocatalyzed PCL brushes were chain extended using lactide in the presence of zirconium n-butoxide to successfully grow PCL/PLA block copolymer (PCL-b-PLA) brushes with a final thickness of 55 nm. The degradation properties of "grafted from" PCL brush and the PCL-b-PLA brush were compared to "grafted to" PCL brushes, and we observed that the brush density plays a major role in degradation kinetics. Solutions of methanol/water at pH 14 were used to better solvate the brushes and increase the kinetics of degradation. This framework enables a control of degradation that allows for the precise removal of these coatings.

Hierarchically macro–mesoporous ZrO2–TiO2 composites with enhanced photocatalytic activity

Hierarchically macro–mesoporous ZrO2–TiO2 composite materials were prepared based on a facile surfactant self-assembly method with titanium isopropoxide (TIP) and zirconium n-butoxide as precursors. The ZrO2 content in the composites (2.0–9.8%) was easily controlled by adjusting the molar ratio of the two precursors, while maintaining the porous structures of the materials. SEM results demonstrated that the ZrO2–TiO2 composites were featured by paralleled channels (50–500nm) and interparticle pores (~8nm) in the walls. The photocatalytic activities of the novel composites were remarkably higher than corresponding pure macro–mesoporous TiO2 and ZrO2 materials in the decomposition of Rhodamine B (RhB) under UV light radiation. The ZrO2–TiO2 sample with 6.9% of ZrO2 was proved to be the most efficient catalyst with degradation kinetic constant twice larger than that of the pure macroporous TiO2. Trapping experiments indicated that photogenerated holes and radicals were all vital to the photocatalytic process under UV light irradiation. ESR measurements gave the direct evidence that the active radicals •OH and O2•− were responsible for the photodecomposition of RhB.

The Effect of pH of the Aging Solution on Microstructure of Silica/Zirconia Aerogel

ZrO2 wet gel was prepared using zirconium n-butoxide as precursor and 1,2-propylene oxide (PO) as a gelation agent in sol-gel process. Then, tetraethoxysilane (TEOS) was used to strengthen the wet gel in aging process. Finally, the monolithic silica/zirconia aerogel was obtained by supercritical fluid drying. N2 adsorption-desorption method, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were used to characterize microstructure of the aerogel. The influence of pH of the aging solution on microstructure of silica/zirconia aerogel was studied. The results indicate that the particle size distribution of SiO2/ZrO2 aerogel was more uniform and less aggregate when aging in acid solution. However, the average pore diameter and particle size of SiO2/ZrO2 aerogel was increased by aging in alkaline solution. Aging in alkaline condition was useful for largening the pore size of SiO2/ZrO2 aerogel, and the maximum specific surface area and pore volume were obtained at pH=9. Meanwhile, different reactions were produced between the acid/alkaline solution and the hydroxyl of SiO2/ZrO2 aerogel, and the ester group/amino group was obtained relatively which can modify the network of aerogel and decrease the shrinkage of aerogel during the supercritical fluid drying.

EFFECT OF THE ADDITION OF PHOSPHOTUNGSTIC ACID ON THE THERMAL STABILITY OF ZIRCONIUM OXIDE

Zirconium hydroxide [Zr(OH)4] was synthesized by the sol-gel method using zirconium n-butoxide and 1-butanol as synthesis precursors. A part of the synthesized material was impregnated with phosphotungstic acid (H3PW12O40) in order to evaluate the effect of this dopant agent on the thermal, textural and structural properties of zirconium oxide (ZrO2). Pure and modified hydroxides were calcined in an air flow at 400, 500 and 600°C for 3 h and afterwards were characterized by thermal analysis, infrared spectroscopy, X-ray diffraction and nitrogen physisorption. Results showed that the interaction between the heteropolyanion and zirconium oxide surface produces a stabilizing effect of the crystalline structure and delays the drastic sintering of the material caused by the thermal treatment, obtaining high specific surface areas and small crystallite size for the modified zirconium oxides.

Obtention of ZrO2–SiO2 hydrogen permselective membrane by chemical vapor deposition method

This paper reports about the zirconia (ZrO2)–silica (SiO2) composite membrane prepared by the chemical vapor deposition (CVD) method. A porous alumina tube having a pore size of 100nm was modified by CVD using the precursor solution (mixture solution of zirconium n-butoxide and tetraethylorthosilicate with weight percent of 1:1) as a ZrO2–SiO2 composite source. The CVD treatment was carried out at 600°C, 650°C and 700°C. The single-component with the presence of H2 and N2 gases in the prepared Zr–Si composite membrane was measured at 300–600°C. Hydrogen presence at 600°C was about 7.3×10−8mol(m2Pas)−1 and 2.7×10−8mol(m2Pas)−1 for ZS650-2 and ZS700 membrane, respectively. The H2/N2 gases selectivity at 600°C were 24.5 and 35.8 for the ZS650-2 and ZS700 membrane, respectively. The stability test was carried out at 450°C with an increase of exposure time in the water vapor. It was confirmed that permeances of H2 and N2 gases at through the prepared ZrO2–SiO2 composite membrane did not change with an increase of exposure time in the presence of water vapor.

Zirconia‐based Aerogels via Hydrolysis of Salts and Alkoxides: The Influence of the Synthesis Procedures on the Properties of the Aerogels

This contribution aims at evaluating different synthesis procedures leading to zirconia-based aerogels. A series of undoped and yttrium-doped zirconia aerogels have been prepared via hydrolysis and condensation reaction of different alkoxy- and different inorganic salt-based precursors followed by supercritical drying. Well-established but deleterious zirconium n-propoxide (TPOZ) or zirconium n-butoxide (TBOZ) were used as metal precursors in combination with acids like nitric acid and acetic acid as auxiliary agent for the generation of non-yttrium stabilized zirconia aerogels. Yttrium-stabilized zirconia aerogels as well as pure zirconia aerogels were obtained by the salt route starting from ZrCl4 and crosslinking agents like propylene oxide or acetylacetone. The characteristics of the products were analyzed by nitrogen adsorption measurements, electron microscopy, and X-ray scattering. It turned out that with respect to all relevant properties of the aerogels as well as the practicability of the synthesis procedures, approaches based on inexpensive non-toxic salt precursors are the methods of choice. The salt-based approaches allow not only for low-cost, easy-to-handle synthesis procedures with realizable gelation times of less than 60 seconds, but also delivered the products with the highest surface area (449 m(2) g(-1) for ZrCl4) within this series of syntheses.

UV-directly patternable organic–inorganic hybrid composite dielectrics for organic thin-film transistors

A research on the design, synthesis, and characterization of novel cross-linked polymer organic–inorganic hybrid materials as gate insulators for organic thin-film transistors (OTFTs) with vanadyl-phthalocyanine as the organic semiconductor is presented. The hybrid films (0.5–1.2μm thick) can be easily prepared by sol–gel technology and fabricated by spin-coating a mixture of zirconium n-butoxide sol with a side-chain triethoxysilane-capped polyurethane solution in ambient conditions, followed by curing at low temperatures (∼120°C) and cross-linking under UV light. OTFTs with this film as gate insulator were achieved with good processability, high charge-carrier mobility of 0.56cm2/Vs, surface roughness of around 0.49–0.59nm, ultralow threshold of −6V, and ultralow leakage of 0.24mA. Hybrid films with various compositions were investigated, and the results showed that the field-effect mobility of the OTFTs was dominated by the high dielectric constant component ZrO2. The result indicated that these hybrid materials are promising candidates for the exploration of devices using OTFTs.

Synthesis of polymer/zirconium hydroxide core–shell microspheres and the hollow porous zirconium oxide microspheres

Narrow-disperse poly(N,N′-methylenebisacryamide-co-methacrylic acid)/zirconium hydroxide (P(MBA-co-MAA)/Zr(OH)4) core–shell composite microspheres were synthesized by the controlled sol–gel hydrolysis of inorganic zirconium n-butoxide (Zr(OBu)4) precursor in ethanol and acetonitrile mixed solvent with P(MBA-co-MAA) microspheres as templates. The thickness of the outer inorganic Zr(OH)4 shell-layer was well-controlled via altering the mass ratio of Zr(OBu)4 to P(MBA-co-MAA) core particles as well as the water used for the hydrolysis. The corresponding hollow porous zirconium oxide (ZrO2) microspheres were obtained after the selective removal of P(MBA-co-MAA) core via the calcination of P(MBA-co-MAA)/Zr(OH)4 core–shell microspheres under 550 °C for 4 h in air. The structure and morphology of the resultant core–shell microspheres and the hollow porous ZrO2 microspheres were characterized by transmission electron microscopy (TEM), STEM together with EDX spectrum, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, micromeritic analyzer, and thermogravimetric (TGA) analysis.

Preparation and characterization of Au–ZrO2–SiO2 nanocomposite spheres and their application in enrichment and detection of organophosphorus agents

Au–ZrO2–SiO2 nanocomposite spheres were synthesized and used as selective sorbents for the solid-phase extraction (SPE) of organophosphorous agents. A non-enzymatic electrochemical sensor based on a Au–ZrO2–SiO2 modified electrode was developed for the selective detection of organophosphorous pesticides (OPs). The Au–ZrO2–SiO2 nanocomposite spheres were synthesized by the hydrolysis and condensation of zirconium n-butoxide (TBOZ) on the surface of SiO2 spheres and then the introduction of gold nanoparticles on the surface. Transmission electron microscopy and X-ray photoelectron spectroscopy were performed to characterize the formation of the nanocomposite spheres. Fast extraction of OP was achieved by the Au–ZrO2–SiO2 modified electrode within 5 min via the specific affinity between zirconia and the phosphoric group. The assay yields a broad concentration range of paraoxon-ethyl from 1.0 to 500 ng mL−1 with a detection limit of 0.5 ng mL−1. This selective and sensitive method holds great promise for the enrichment and detection of OPs.

Preparation and characterization of polyphosphotungstate/ZrO 2 nanocomposite and their sonocatalytic and photocatalytic activity under UV light illumination

Polyoxometalates (POM) supported on zirconia, H 3PW 12O 40/ZrO 2, were prepared by incorporating polyphosphotungstate into a zirconia matrix via sol–gel technique that involving the hydrolysis of zirconium (IV) n-butoxide, Zr ( n-OBu) 4, as the ZrO 2 source. This insoluble and readily separable catalyst was characterized by using XRD, FT-IR, SEM, and UV diffuse reflectance spectroscopy (UV-DRS), indicating that the polyphosphotungstate was chemically attached to the zirconia supports, and primary Keggin structure remained intact. The photocatalytic and sonocatalytic activity of the supported polyphosphotungstate was tested via degradation of different dyes in aqueous solutions. The POM–ZrO 2 nanocomposite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure ZrO 2.

Steric factor in ligand displacement of zirconium alkoxides dissolved in alcohols

The present study indicates EXAFS direct structural data obtained for zirconium ethoxide, iso- and n-propoxide are alike those for zirconium n-butoxide complexes. This is evident for agreement of structural units of abovementioned alkoxides complexes. Our group developed structural model of n-butoxide earlier. Six interconnected tetramers assemble a structural unit of the alkoxides under study. The tetramers build of zirconium atoms in the highly flattened pyramid corners. Four zirconium atoms are bonded in series by double bridges through oxygen atoms of alkoxide ligands. Two of the four zirconium atoms are bias bonded by single ligand bridges. The distances between pairs of zirconium atoms inside the tetramer are 3.3 and 3.5 Å. Tetramers are linked together also by a single ligand bridges. The distance between zirconium atoms of the two neighbor tetramers is 3.9 Å. Primary particles (tetramer sextet) form aggregates in a solution. Possible shapes of the anisotropically sized aggregates is a large diameter cylinder with small height (a disk), or a small diameter cylinder with large height (a rod). Primary particles composed through ligands. The distance between the neighbor zirconium atoms of different primary particles is 4.8 or 5.1 Å depending on the coordination nature and the neighboring particles number.

A hierarchic structure in zirconium butoxide complexes in n-butanol solutions

The structure of particles in zirconium n-butoxide solutions in n-butyl alcohol is determined by means of EXAFS, SAXS, and molecular mechanics modeling. Zirconium atoms are found to be bonded to each other via the oxygen atom and to form large anisotropic particles in the solution. Primary particles have a shape close to spherical; their diameter together with the solvate shell is 28.9 A. These particles then aggregate into anisotropic structures. During solution aging under normal conditions without contact with the atmosphere, the particle anisotropy increases because of the aggregation of complexes. When the solution concentration decreases, the particles are divided into primary spherical particles with a characteristic size of 28.9 A. The described changes are confirmed by a decrease in the number of Zr-Zr distances of 4.8 A and 5.1 A, which according to the EXAFS data, correspond to the bonds between the primary particles. The characteristic maximum sizes of particles in solutions with concentrations from 0.1 g to 0.003 g ZrO2/ml are 160–80 A.

Metathesis of carbon dioxide and phenyl isocyanate catalysed by group(IV) metal alkoxides: An experimental and computational study

The insertion reactions of zirconium(IV) n-butoxide and titanium(IV) n-butoxide with a heterocumulene like carbodiimide, carbon dioxide or phenyl isocyanate are compared. Both give an intermediate which carries out metathesis at elevated temperatures by inserting a second heterocumulene in a head-to-head fashion. The intermediate metallacycle extrudes a new heterocumulene, different from the two that have inserted leading to metathesis. As the reaction is reversible, catalytic metathesis is feasible. In stoichiometric reactions heterocumulene insertion, metathesis and metathesis cum insertion products are observed. However, catalytic amounts of the metal alkoxide primarily led to metathesis products. It is shown that zirconium alkoxides promote catalytic metathesis (isocyanates, carbon dioxide) more efficiently than the corresponding titanium alkoxide. The difference in the metathetic activity of these alkoxides has been explained by a computational study using model complexes Ti(OMe)4 (1bTi) and Zr(OMe)4 (1bZr). The computation was carried out at the B3LYP/LANL2DZ level of theory. Zirconium(IV) n-butoxide promotes heterocumulene metathesis more efficiently than titanium(IV) n-butoxide. Computational studies indicate that double insertion in a head-to-head fashion, which is a key for metathesis to occur, is thermodynamically favoured for zirconium(IV) alkoxide compared to titanium(IV) alkoxide.

From thioxo cluster to dithio cluster: exploring the chemistry of polynuclear zirconium complexes with S,O and S,S ligands.

Three different zirconium thio and oxothio clusters, characterized by different coordination modes of dithioacetate and/or monothioacetate ligands, were obtained by the reaction of monothioacetic acid with zirconium n-butoxide, Zr(OnBu)4, in different experimental conditions. In particular, we isolated the three polynuclear Zr3(μ3-SSSCCH3)2(SSCCH3)6·2nBuOH (Zr3), Zr4(μ3-O)2(μ−η1-SOCCH3)2(SOCCH3)8(OnBu)2 (Zr4), and Zr6(μ3-O)5(μ-SOCCH3)2(μ-OOCCH3)(SOCCH3)11(nBuOH) (Zr6) derivatives, presenting some peculiar characteristics. Zr6 has an unusual star-shaped structure. Only sulfur-based ligands, viz., chelating dithioacetate monoanions and an unusual ethane-1,1,1-trithiolate group μ3 coordinating the Zr ions, were observed in the case of Zr3. 1D and 2D NMR analyses confirmed the presence of differently coordinated ligands. Raman spectroscopy was further used to characterize the new polynuclear complexes. Time-resolved extended X-ray absorption fine structure measurements, devoted to unraveling the cluster formation mechanisms, evidenced a fast coordination of sulfur ligands and subsequent relatively rapid rearrangements.