Amorphous Zirconium Research Articles

Two Step Synthesis of Fluorescent Zirconia Oxide Amorphous Nanosheets for highly sensitive detection of a cancer marker

This study has reported the first-ever fluorescent 2D amorphous zirconia nanosheets (ZrO2 NS) synthesis approach and their utilization for the detection of tyrosine. We have reported a novel yet simple approach to the synthesis approach by dissolving ZrCl4 in ethanol followed by the reduction with the use of sodium hydroxide. It is suggested that NaOH partially reduces Zr4+ and for Zr-OH conjugates finally forming ZrO2 sheet structure by Cl− templating due to the high affinity of reduced Zr towards oxygen. The as-synthesized 2D amorphous zirconia nanosheet suspension in ethanol resulted in a blue color fluorescence with an emission maximum of 430 nm. This nanosheet system shows a unique quenching property by tyrosine in both PBS buffer and human blood serum. This system was utilized to develop a fluorometric sensing platform for a cancer biomarker, tyrosine. The system showed firm results in 1-100 nM range with a LOD of 14.9 nM in human blood serum and 8.4 nM in PBS. This study has opened a new insight into utilizing 2D amorphous zirconia nanostructures in a novel way and also it creates a platform for using the 2D amorphous NS as a biosensor to detect cancer markers in the medical and biomedicine fields too.

In situ deposition of amorphous zirconia to enhance corrosion and tribocorrosion resistance of dentin surface

With global aging and the prevalence of acidic diets, dentin exposure is becoming commonplace; thus, it is necessary to develop a treatment technology that combines resistance to wear, corrosion, and tribocorrosion. Herein, we present a promising treatment strategy that induces in situ deposition of amorphous zirconia on exposed dentin surface. The deposited amorphous zirconia bonds to dentin surface through strong chemical connection, and acts as a protective layer against acid attack and contact wear due to its acid-inertness and good mechanical properties. Consequently, the treated dentin surface exhibits encouraging corrosion and tribocorrosion performance. The deposit also provides antibacterial protection.

Polymerised forms in the zirconium conversion coatings on cold-rolled steel: proof of concept

This study validates the proposed polymerised structure, including tetrameric polynuclear species, of solid amorphous oxyhydroxide zirconium conversion coatings on cold-rolled steel using ToF-SIMS. Tetramers are formed at pH near 4 (and possibly higher), with thickness increasing over extended conversion times. EIS in simulated acid rain further demonstrates that optimal coating formation requires a pH of at least 4 and a sufficient conversion time for adequate thickness, confirmed by the high-frequency EIS loop. Tetramer forms were not observed when the coatings were prepared at lower pH or shorter conversion time, proving that the polymerisation step is crucial for obtaining the coatings offering adequate corrosion protection.

An investigation on the amorphous zirconium phosphate compositing with cotton for the removal of heavy metal ions

In this study, amorphous zirconium phosphate were synthesized (Am-ZrP) through a facile method and then composited with cotton fiber (Am-Co) for the utilization of heavy metal ions adsorptive elimination. In the research, Am-Co exhibited a higher adsorption capacities compared with Am-ZrP, with 85.69 mg/g for Cu2+, 30.73 mg/g for Ni2+, 56.74 mg/g for Cd2+. The adsorption kinetics of the adsorbents was extrapolated using pseudo-first-order and pseudo-second-order kinetic model and the experimental data were found to fit pseudo-second-order more than pseudo-first-order. Langmuir and Freundlich isotherm model were also applied in the study to reflect the interaction between adsorbate and adsorbent. In this research, the adsorption isotherm of Am-ZrP and Am-Co fitted the Langmuir model favorably. The results indicated that the Am-Co was a promising candidate for practical application in the treatment of wastewater contaminated by heavy metal ions.

Experimental Study on Coefficient of Restitution of Small-Sized Spherical Particles during Low-Speed Impact

This study presents experimental investigations on the normal restitution coefficients of a titanium bead (Ti), zirconia bead (ZrO2), and amorphous zirconium alloy sphere (Amor). The research explores the influence of particle diameter and collision velocity on the normal restitution coefficient between two independent, identical spherical particles of different materials. The experimental findings demonstrate that increasing the particle diameter results in more effective plastic deformation, leading to higher energy losses and, subsequently, smaller coefficients of restitution. Similarly, higher particle velocities cause more energy dissipation during collisions, resulting in smaller restitution coefficients. Comparing particles of different materials, those with larger yield strengths exhibit more elastic behavior, experience less initial energy loss due to deformation, and reach the maximum restitution coefficient (elastic state) with fewer collisions. This finding suggests that material properties significantly influence the overall energy dissipation and elastic response in the particles. To validate the experimental results, existing models are compared and discussed. Furthermore, potential physical mechanisms responsible for the observed behavior are explored, providing valuable insights into the collision dynamics in spherical particle interactions. Overall, this study contributes to a better understanding of the factors affecting the normal restitution coefficient in particle collisions, enabling the design and optimization of particle systems for diverse applications in condensed matter and related fields.

Combinative effects of L-asparagine ligation and pH modifications in tuning the surface and pore environment of biocompatible amorphous zirconium coordination polymers

Combinative effects of L-asparagine ligation and pH modifications in tuning the surface and pore environment of biocompatible amorphous zirconium coordination polymers

Aerobic homocoupling of arylboronic acids using Cu-doped amorphous zirconia: impact of catalyst amorphousness on reaction efficiency

Homocoupling of arylboronic acids under additive-free and mild conditions has been developed with CuO/amorphous-ZrO2 as a heterogeneous catalyst.

Effect of phase transformation on the electrochemical supercapacitive behavior of thermally exfoliated zirconia

Amorphous and crystalline zirconia (ZrO2) are successfully synthesized through a rapid thermal exfoliation process. The crystal structure and phase purity of exfoliated materials are examined using XRD. Crystalline ZrO2 reveals the formation of a tetragonal phase. Amorphous zirconia possesses a specific surface area of 45 m2/g. As synthesized, amorphous zirconia provides a specific capacity of 1406C/g at 2 A/g (3-electrode measurements). A two-electrode asymmetric supercapacitor of activated carbon, amorphous zirconia (ZrO2//AC), exhibits a better electrochemical performance than its crystalline phase. The amorphous ZrO2-based asymmetric supercapacitor gives a specific capacitance of 160 F/g at 3 A/g. The device delivered an energy density of 47.6 Wh/kg at a power density of 2.2 kW/kg. These high energy and power density values of asymmetric amorphous ZrO2 supercapacitors outperform most of the reported ZrO2-based electrode materials. Amorphous ZrO2 is a promising electrode material in terms of its capacitance retention of ∼75 % over 10,000 cycles. The as-developed device has a rate capability of 35 % at a current density of 25 A/g and a self-discharge current of 2.6 mA.

The combined effect of hydroxyapatite and zirconia coatings on magnesium-based-implant to improve corrosion resistance and induce antibacterial activity

In this research, zirconium has been used in two methods of, single-step and double-step, to improve the anticorrosion properties of Hydroxyapatite (HA) coating. The corrosion behavior of the samples and the performance of the coatings in the physiological environment were investigated by EIS and DC polarization tests in 3.5 wt% sodium chloride and SBF solution, respectively. The results of the electrochemical assays showed that the best resistance against corrosion and biocorrosion is obtained for the sample prepared by the double-step method (HAopt/Zropt sample). FE-SEM and XRD were used to examine the morphology and composition of the coatings that confirmed the formation of HA crystals and the amorphous zirconium layer. According to the antibacterial results, HA/zirconia coating provided a remarkable antibacterial performance (RP =99.9%) against Staphylococcus aureus gram-positive and Escherichia coli gram-negative bacteria. Also, HAopt/Zropt sample provided the highest corrosion resistance of about 9000 ohm.cm2 in NaCl, and |Z|0.01 Hz= 3.5 × 105 ohm.cm2 in SBF solution in a prolonged immersion period.

Amorphous zirconium phosphate as a recycled material anchored cobalt for catalytic degradation of phenacetin via peroxymonosulfate activation

Herein, zirconium phosphate as a recycled material was used for the first time to support cobalt (Co-ZrP) serving as a catalyst for activating peroxymonosulfate (PMS) to remove phenacetin (PNT). It was found that PNT (5 mg L−1) was completely eliminated in the Co-ZrP (0.2 g L−1)/PMS (2 mM) system in an initial pH range of 5 to 7 within 10 min. The pseudo-first-order rate constant of PNT degradation by PMS combined with Co-ZrP was 0.625 min−1, far faster than those with ZrP (0.0065 min−1) and with Co3O4 (0.104 min−1). The introduction of HA and HCO3− significantly inhibited PNT removal, while the addition of H2PO4− accelerated PNT elimination in the Co-ZrP/PMS system. Nevertheless, PNT could still be completely removed by Co-ZrP-activated PMS in actual water. Recycling experiments indicated that the degradation efficiency of PNT could reach 98 % after four cycles and calcining Co-ZrP could completely restore its catalytic activity. In addition, effective decomposition of chloramphenicol, bisphenol A, sulfamethazine and rhodamine B was also achieved by Co-ZrP-activated PMS within 15 min. Hence, the combination of Co-ZrP and PMS had great potential in removing organic pollutants from water environment. EPR analysis and quenching tests suggested that the rapid degradation of PNT was mainly ascribed to the generation of •OH and SO4•− in the Co-ZrP/PMS system. Based on HPLC-HRMS analysis, the main degradation products were determined and the possible degradation pathways were further proposed.

Silver zirconium oxide cermet coatings spray deposited onto galvanized steel sheet for low temperature solar applications

A new type of cermet coating, with potential use as low-cost solar thermal absorber has been developed using spray pyrolysis. It consists of crystalline silver nanoparticles embedded in amorphous zirconia and was obtained by spraying aqueous precursor solutions onto aluminized carbon steel sheets at 200 °C. It was found that simultaneous spraying of silver and zirconium solutions led to a considerable reduction, in the nanometer range, of silver particle size distribution. Hence, we comparatively studied the cermet coatings obtained by A) sequentially or B) simultaneously spraying silver and zirconium solutions. For the latter case, a zirconia anti-reflection layer was sprayed on top. Both coating systems were studied by SEM, AFM, HRTEM/EDS and UV-VIS-IR spectroscopy with respect to silver particle size distribution. Optical parameters like solar absorptance (AM 1.5) and thermal emittance (373 K) were determined from absolute hemispherical reflectance, and a performance coefficient was calculated in order to evaluate the solar selectivity of the coatings. The comparison showed that smaller silver particles lead to an increase in solar selectivity and that the size reduction is due to an effective encapsulation by zirconia of the silver particles when spraying silver and zirconium precursors simultaneously. Furthermore, HRTEM confirmed the metallic and crystalline state of the silver nanoparticles embedded in amorphous zirconia.

The Conductivity of PANI/Zirconia Composites: Effect of Amorphous and Crystalline Fillers

This paper reports the results of synthesis and characterization PNI/zirconia composites. PANI/zirconia composites were synthesized by in-situ polymerization. Aniline was used as a monomer, hydrochloric acid as a dopant, ammonium peroxodisulphate as an oxidant and sodium dodecyl benzene sulfonate as a surfactant. The zirconia used is amorphous and crystalline (monoclinic). XRD test results show that the composite has been successfully formed, indicated by the absence of new peaks. FTIR spectrum analysis showed an interaction between PANI and zirconia. Composites with amorphous zirconia fillers have lower conductivity than PANI; on the other hand, composites with monoclinic zirconia fillers have better conductivity than PANI.

Reagentless electrochemically assisted desorption for selective phosphate recovery from wastewater: Proof of concept and mechanism

Adsorption is a promising technology for removing and recovering phosphorus (P) from wastewater. However, the chemical-intensive regeneration of adsorbents increases carbon emissions and introduces potential secondary pollution. Most existing approaches cannot achieve simultaneous P desorption and selective recovery. For this purpose, a new-type electrochemically assisted phosphate desorption and recovery (EPDR) process was investigated and developed for the efficient desorption and recovery of P and simultaneous regeneration of the adsorbent in situ. In the EPDR process, the adsorbent amorphous zirconium oxide (am-ZrO2) coated carbon felt (CF) was employed as a cathode in an anion-exchange membrane (AEM) water electrolysis cell for P adsorption/desorption and recovery. The P desorption and recovery efficiency from the adsorbent were over 90% at 3.5 V. It was found that the high concentration of OH– at the cathode surface derived from water splitting reaction and electrodialysis under the applied electric field was playing a critical role in the desorption process. Low concentrations of P in actual wastewater were effectively removed, concentrated and recovered under multiple adsorption–desorption cycles with easy-to-scale-up stacked EPDR. The nature of reagent-free, high efficiency and selectivity make EPDR the foundation for developing a cost-effective and green technology for sustainable phosphorus management.

A Perfluorocarbon-Coated ZrP Cation Exchanger with Excellent Ammonium Selectivity and Chemical Stability: An Oral Sorbent for End-Stage Kidney Disease (ESKD).

An oral sorbent to remove NH4+ within the small intestine of end-stage kidney disease (ESKD) patients could reduce blood urea levels and diminish their dialysis treatment burden. But current sorbent materials like amorphous zirconium phosphate particles Zr(HPO4)2·H2O (ZrP) lack the selectivity to remove NH4+ in water solution with other competing ions. Our previous work found that a gas-permeable, hydrophobic polydimethylsiloxane (PDMS) coating on ZrP improved the material's selectivity for NH4+. However, a competing ion Ca2+ was still removed by PDMS-coated ZrP sorbent, and the permeability of the PDMS coating to Ca2+ was increased after low-pH stomach-like condition exposure. An alternative hydrophobic and gas permeable coating has been investigated─perfluorooctyltriethoxysilane (FOTS). The coating was attached in place of PDMS to a tetraethyl orthosilicate-coated ZrP surface. Surface atomic composition analysis and scanning electron microscopy observation verified the successful application of the FOTS coating. Water contact angle analysis validated the FOTS coating was hydrophobic (145.0 ± 3.2°). In vitro competing ion studies indicated the FOTS coating attached to ZrP increased NH4+ removal by 53% versus uncoated ZrP. FOTS offers complete selectivity for NH4+ over Ca2+ with similar NH4+ capacity as the previous PDMS coating. Moreover, FOTS-coated ZrP maintained NH4+ removal capacity and selectivity after the acid exposure study, indicating excellent acid resistance while NH4+ selectivity of ZrP-PDMS decreased by 72%. The results suggested that FOTS-coated ZrP is promising as an oral sorbent for ESKD patients.

Corrosion barrier alumina/zirconia bilayer stack on low Cr steel by direct liquid injection metalorganic chemical vapor deposition

Numerous industrial fields necessitate the development of advanced metallic materials presenting high corrosion resistance in aqueous media and being less expensive than classical high chromium steels. In the present work, amorphous zirconia, alumina and alumina/zirconia coatings have been deposited on 2 wt% chromium steel coupons using an innovative direct liquid injection metal organic chemical vapor deposition process. Scanning electron microscopy and X-ray diffraction reveal that the alumina sublayer acts as an efficient barrier against steel oxidation occurring during the amorphous zirconia deposition performed under O2 at 400 °C. They also show that the steel oxidation occurring concomitantly to the zirconia coating modifies the film morphology by increasing its roughness and thickness, in comparison with the same zirconia coating on alumina. The anticorrosive properties of the thin films have been studied by an immersion test of the bare and coated coupons in deionized water at 80 °C during 6 days and by electrochemical impedance spectroscopy in aqueous sodium chloride solution for 48 h. They reveal that, in contrast to alumina and zirconia monolayers alone, the alumina/zirconia stack acts as a corrosion protection coating in pure water through a synergetic barrier effect against (i) oxidation by alumina and (ii) aqueous corrosion by zirconia.

Adsorption of CO2 on Amorphous and Crystalline Zirconia: A DFT and Experimental Study

Herein, we study the structural and electronic origins of molecular adsorption using experiments and density functional theory (DFT) calculations. We performed X-ray diffraction (XRD) and temperature-programmed desorption (TPD) of CO2 on amorphous zirconia (am-ZrO2) and crystalline (tetragonal and monoclinic) zirconia. Using molecular dynamics simulations, the bulk structures of am-ZrO2 and am-zirconium(IV) hydroxide (am-Zr(OH)4) were obtained and the reproducibility of the experimental structure was confirmed by comparing the radial distribution functions. In addition, the hydroxyl density on the hydrogenated ZrO2 surfaces was found to be consistent with the experimental results. Both experiments and simulations indicate that the adsorption of CO2 on an am-ZrO2 surface is more heterogeneous and weaker than that on a crystalline zirconia surface. Because the charge environment and band structures of crystalline zirconia are approximately the same as those of am-ZrO2, the weak adsorption on the am-ZrO2 surface arises from the fewer and stronger Zr–O bonds on the surface. These findings provide molecular-level insight not only for the adsorption of CO2 but also into the molecular adsorption on ZrO2-based catalysts.

Ultrasmall amorphous zirconia nanoparticles catalyse polyolefin hydrogenolysis

Carbon–carbon bond cleavage reactions, adapted to deconstruct aliphatic hydrocarbon polymers and recover the intrinsic energy and carbon value in plastic waste, have typically been catalysed by metal nanoparticles or air-sensitive organometallics. Metal oxides that serve as supports for these catalysts are typically considered to be inert. Here we show that Earth-abundant, non-reducible zirconia catalyses the hydrogenolysis of polyolefins with activity rivalling that of precious metal nanoparticles. To harness this unusual reactivity, our catalytic architecture localizes ultrasmall amorphous zirconia nanoparticles between two fused platelets of mesoporous silica. Macromolecules translocate from bulk through radial mesopores to the highly active zirconia particles, where the chains undergo selective hydrogenolytic cleavage into a narrow, C18-centred distribution. Calculations indicated that C–H bond heterolysis across a Zr–O bond of a Zr(O)2 adatom model for unsaturated surface sites gives a zirconium hydrocarbyl, which cleaves a C–C bond via β-alkyl elimination.

An amorphous Lewis-acidic zirconium chlorofluoride as HF shuttle: C-F bond activation and formation.

An exceptional HF transfer reaction by C-F bond activation of fluoropentane and a subsequent hydrofluorination of alkynes at room temperature is reported. An amorphous Lewis-acidic Zr chlorofluoride serves as heterogeneous catalyst, which is characterised by an eightfold coordination environment at Zr including chlorine atoms. The studies are seminal in establishing sustainable fluorine chemistry.

Structural Approach to Understanding the Formation of Amorphous Metal Hydroxides.

This study investigates the formation of amorphous tetravalent metal hydroxides, M(OH)4, based on the structural analysis by small- and wide-angle X-ray scattering (SWAXS) and on the electrical potential charge near the surface of M(OH)4 particles. The amorphous zirconium hydroxide solid phases that aged in NaCl and CaCl2 solutions at 25 °C exhibited a hierarchical structure consisting of primary particles of a few nanometers in size and their aggregates more than 100 nm in size. The SWAXS profiles suggested that the size of the primary particles depends on the ionic strength and electrolytes in the sample solutions. The smaller size of the primary particles observed in solutions with higher ionic strength can be explained by the thinner electrical double layer. Additionally, we focused on the ζ potentials of M(OH)4 suspensions in NaCl, NaNO3, and CaCl2 solutions. With the aid of reference systems of metal oxides, MO2, it was found that the ζ potentials were well interpreted by a traditional surface ionization and complexation model, and the size distributions of large aggregates were explained by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory with the ζ potential values. The present study suggests the formation mechanism of amorphous metal hydroxides through a combination of structural analysis and investigation of electrical potentials.

Amorphous zirconium oxide activates peroxymonosulfate for selective degradation of organic compounds: Performance, mechanisms and structure-activity relationship

Application of heterogeneous advanced oxidation processes (AOPs) for wastewater treatment suffers from the low oxidant utilization efficiency, slow catalytic cycling and severe matrix interference. Herein, we report that amorphous zirconium dioxide (aZrO2), a redox-inert metal oxide, can efficiently activate peroxymonosulfate (PMS) to degrade organic micropollutants under very low oxidant doses and complex coexisting matrices. Distinct from conventional AOPs where radicals are formed, the surface Zr(IV)-PMS* complex was identified as the principal reactive species, and primarily conducted oxygen-atom-transfer route with selected molecules. Quantitative structure-activity relationship analysis indicated that the formation of Zr(IV)-PMS* complex was governed by the density of the surface hydroxyl groups. The strong interaction between the Zr atom and PMS caused the deviation of the negative charge from Zr(IV) metal sites to the oxidant. As a result, the O-O bond of the adsorbed PMS was prolonged and its oxidation potential elevated, which enabled it to directly react with contaminants. This study indicates the potential of aZrO2 as a novel and eco-friendly catalyst that activates PMS to selectively tackle organic contaminants, and sheds light on the designing of Fenton-like catalysts using redox-inert metals.