ZrO2 Nanostructures Research Articles

Tuning the crystallinity of ZrO2 nanostructures derived from thermolysis of Zr-based aspartic acid/succinic acid MOFs for energy storage application

This paper investigated the effect of calcination temperatures on the structural, and capacitance of Zr-MOFs as an electrode material for supercapacitor applications. MIP-202 and 203 were prepared solvothermally, using zirconium clusters with aspartic acid and succinic acid as ligands, respectively. These MOFs are subject to heat treatment at 350 and 500 °C to be converted to ZrO2 derived from MOFs. As a result, we have six materials: MIP-202 (bare), MIP-202 (350 °C), MIP-202 (500 °C), MIP-203 (bare), MIP-203 (350 °C), and MIP-203 (500 °C). The structure of compounds were confirmed by X-ray diffraction analysis (XRD), N2 adsorption–desorption measurements, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). We investigated the differences in electrochemical properties in the amorphous and crystalline phases. The electrochemical performances of fabricated electrodes, including as-prepared Zr-based MOFs before heat treatment (MIP-202, MIP-203) and after that, at 350 and 500 °C, are demonstrated via electrochemical tests in a three-electrode configuration. Among the materials, MIP-202 (350) exhibits the best electrochemical efficiency due to its amorphous structure and high specific surface area, delivering a high specific capacitance of 308 F g−1 at a current density of 2 A g−1. To further identifying electrochemical properties of the electrode, an asymmetric supercapacitor was constructed utilizing graphene oxide (GO) as the anode and MIP-202 (350) as the cathode. The device provided long cyclic life durability (86 % specific capacitance maintenance after 3000 cycles) and high energy density of 16.06 Wh kg−1 and high-power density 40,000 W kg−1.

Morphology, structural and photoluminescence properties of shaping triple semiconductor YxCoO:ZrO2 nanostructures

In the present investigation, YxCoO:ZrO2 (x = 0.1, 0.3, 0.4) nanostructures (NS) are synthesized by co-precipitation and surface reduction methods using triethanol amine as surfactant and hydrazine hydrate as reducing agent. Triple-shaped semiconductor crystal features, morphology, optical absorptivity and chemical composition are determined by XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), UV–Vis and X-ray photoelectron spectroscopy. XRD patterns revealed mixed phase of tetragonal and cubic structure of YxCoO: ZrO2 with less impurity peaks. SEM morphology indicates nanoparticles (NPs) of YxCoO:ZrO2 spherical in nature with particle agglomerations. Average Grain size, grain boundary and interpore diameter were found to be ~ 55 nm, ~ 78 nm and ~ 115 nm, respectively. FTIR spectra of YxCoO:ZrO2 (0 ≤ x ≤ 0.4) show stretching and bending peaks at ~ 533/cm (O–Y–O bond), ~ 1024/cm (Zr–O–Zr bond), broad peak at ~ 3319/cm (Y–OH) and optical absorptivity of YxCoO:ZrO2 (0 ≤ x ≤ 0.4) with λmax spread over 286 nm to 270 nm, and absorption edges appeared in between 189 and 254 nm. Chemical compositional analysis exhibited binding energies of singlet O1s at 529.8 eV, Y 3d 5/2 and Y 3d3/2 observed at 157.8 eV and 163.9 eV, respectively, while Zr 3d5/2 and Zr 3d3/2 are observed at 180.4 eV and 182.7 eV. Photoluminescence spectrum (PL) of YxCoOZrO2 NS exhibit peaks centred around ~ 455 nm (UV region) in case of Y0.4Co0.5OZr0.1O2 NS and for Y0.3Co0.5OZr0.2O2 NS ~ 538 nm (visible region) with various Y-, O- and Co-related native defects. Emission band was observed at UV region with ~ 415 nm to ~ 480 nm broad peak (Y0.4Co0.5OZr0.1O2 NS, λexcitation = 380 nm) and ~ 502 nm to ~ 582 nm in case of Y0.3Co0.5OZr0.2O2 NS with λexcitation = 410 nm. PL emission spectra of YxCoO:ZrO2 have two emission peaks centred at ~ 455 nm and ~ 538 nm with emissions bands with blue and green wavelengths. The transitions can be ascertained with shielding of 4f shells of Y+3 ions by 6s, 5d shells by the interaction of the other Y+3 ions.

Towards Clinical Translation: Optimized Fabrication of Controlled Nanostructures on Implant-Relevant Curved Zirconium Surfaces.

Anodization enables fabrication of controlled nanotopographies on Ti implants to offer tailorable bioactivity and local therapy. However, anodization of Zr implants to fabricate ZrO2 nanostructures remains underexplored and are limited to the modification of easy-to-manage flat Zr foils, which do not represent the shape of clinically used implants. In this pioneering study, we report extensive optimization of various nanostructures on implant-relevant micro-rough Zr curved surfaces, bringing this technology closer to clinical translation. Further, we explore the use of sonication to remove the top nanoporous layer to reveal the underlying nanotubes. Nano-engineered Zr surfaces can be applied towards enhancing the bioactivity and therapeutic potential of conventional Zr-based implants.

Nanostructured templates for critical current density enhancement in YBa2Cu3O7–x films

YBa2Cu3O7–x (YBCO) films grown by metal-organic decomposition (MOD) are promising candidates for the production of high performance high temperature superconductors (HTS) tapes. Moreover, artificial pinning centers (APCs) introduction proved to be a powerful tool for the improvement of transport properties in YBCO films. Along with the widely employed pinning strategies, such as the introduction of secondary phases in the YBCO matrix, a less studied approach is the nanostructuring of the YBCO substrate, in order to hinder its growth and to obtain a highly defective superconductive layer. In this work, oxide nanostructures were deposited on crystalline substrates via polymer assisted deposition (PAD), a low cost, highly versatile technique, so as to create nanoparticles that could interfere with epitaxial growth of chemical YBCO films. Preliminary analyses of the superconducting films grown on BaZrO3 (BZO) and ZrO2 (ZO) nanostructures showed that the decorated templates are highly effective in straining the YBCO matrix, leading to a significant improvement in transport properties. In fact, we obtain an increase of the critical current density, at 77 K, for YBCO grown on BZO and ZO decorated substrate of the order of 3 times at 2 T and even of the order of 8 times at 5 T with respect to the YBCO grown on bare substrate. The improvement of the pinning properties can be related to the intrinsic modification of the crystal structure of YBCO film due to the presence of these nanoparticles, in agreement with transmission electron microscopy (TEM) analysis performed.

Synthesis and characterization of pure and Cd doped ZrO2 nano structures for ammonia sensing application

Pure and Cd doped (5% and 10%) ZrO 2 nano structured powder were synthesized by conventional precipitation process and the films were fabricated by drop casting method on the glass substrate. The X-ray diffraction pattern shows that the samples have monoclinic structure with no impurity peaks, and doping element induces a minor shift in peak positions. SEM images disclose that the samples are in spherical like morphology. The presence of oxygen vacancies in the samples were fixed by photoluminescence evaluation. The gas sensing potentials of the prepared films were analyzed for different temperatures and for various ammonia concentrations. The fetched data interprets that all the processed films exhibit very good response towards the target gas ammonia, especially 10% Cd doped ZrO 2 offers response as high as, 42.08%. Further, it shows an excellent response and recovery time of about 49 s and 51 s respectively. Thus, an embellished gas response of zirconium metal oxide is benefited by cadmium doping.

Formation of anodic ZrO2 nanostructures in NH4F/ethylene glycol electrolyte

The aim of this study is to investigate the morphology and surface species of ZrO2 film formed in a fluorinated ethylene glycol electrolyte by anodization process. In this work, no water was added into the NH4F/ethylene glycol electrolyte. Possible formation mechanism of anodic ZrO2 nanostructures in the NH4F/EG electrolyte was also explored. As a result, the porous ZrO2 film with the thickness of 1.5 – 2.5 µm was produced. From the top view, it is observed that the surface consists of rings with diameters of 100 – 160 nm. However, the oxide does not consist of any tubular structure. The FTIR spectrum of the film shows that the top of anodic ZrO2 film is covered by anion contamination, e.g. OH− and CO3 −.

Manganese promoted TiO2 and ZrO2 nanostructures for soot combustion with boosted efficiency

TiO2, ZrO2 and mixed-oxide (TiO2-ZrO2) materials with manganese as active promoter were synthesized. The performance of these catalysts was tested in the diesel soot oxidation reaction. The soot conversion light-off temperature was remarkably lowered by manganese in the mixed-oxide (TiO2-ZrO2) in comparison with manganese in the TiO2 and ZrO2 catalysts. On the other hand, the mixed oxide enhanced surface defects because of the promotional role played by the ZrO2 interface, which led to the formation and stabilization of defect sites. In addition, the O2/TPD characterization revealed two peaks corresponding to desorption of oxygen species and desorption of lattice oxygen between 120 and 500 °C, which was correlated with the catalytic activity. The manganese-doped-mixed-oxide (TiO2-ZrO2) catalyst displayed structural stability, higher surface area, presence of Mn3+ and Mn4+ species and soot conversion light-off temperature of 260 °C, which was preserved after three reaction cycles.

A facile microwave synthesis of rGO, ZrO2 and rGO–ZrO2 nanocomposite and their room temperature gas sensing properties

Microwave irradiation technique provides a simple and quick synthesis route for nanomaterials at controlled experimental conditions. In this view, nanostructures of rGO, ZrO2, and rGO–ZrO2 composite were synthesized using microwave synthesis technique. Herein, we experimented the preparation of rGO using optimized conditions using convection mode at 373 K in a commercial microwave oven. Structural properties revealed the formation of mixed phases of the orthorhombic and rhombohedral crystal structure of ZrO2. The preferential plane orientation was found to be in c-axis (002) for rGO–ZrO2 nanocomposite, which revealed the predominance of rGO in the nanocomposite. Morphology of the prepared nanostructures exhibited agglomerated sheets, denser nanograins and randomly aggregated nanosheets for rGO, ZrO2, and mixed nanocomposite respectively. Room temperature gas sensing properties of the prepared nanostructures were investigated and reported. rGO showed responses of 5.3 and 5.2 towards 200 ppm of trimethylamine (TMA) and methanol. ZrO2 nanostructure showed a response of 35 towards 200 ppm of ammonia with response–recovery times of 91 and 6 s.

One-step hydrothermal synthesis of high surface area m-ZrO2 nanorings with lower band gap, blue emission and high photocatalytic activity

Herein, monoclinic ZrO2 (m-ZrO2) nanostructures were prepared by a facile one-step hydrothermal method. As-prepared products showed ring-like nanostructures with an average size of ~ 23.1 nm and high surface area. The ring-like m-ZrO2 nanostructures exhibited broad absorption spectra in the visible region (400–800 nm) and a low band gap of 3.7 eV. Moreover, blue emission was also shown by m-ZrO2 nanostructures under the excitation of wavelength 300 nm. As-prepared m-ZrO2 nanostructures show high photocatalytic performance under UV irradiation. The lower band, high surface area and presence of oxygen vacancies may be attributed to the excellent performance of ring-like m-ZrO2 nanostructures as a photocatalyst.

Gas sensing performances of pure and Cu-doped ZrO2 nano structures

In this paper, we report the gas sensing studies of pure and Cu-doped (3%, 5%, 10%, and 15%) ZrO2 synthesized by conventional precipitation method using ZrOCl2·8H2O and CuCl2·2H2O as precursor, distilled water as solvent and NaOH as a stabilizing agent. The films have been prepared by drop casting method and subjected to XRD, SEM, I–V measurement, UV-DRS spectroscopy and photoluminescence studies to characterize the material properties. SEM images shows that the samples have uniform distributed spherical like structure. The I–V measurement certifies the ohmic contact of the samples with electrode. The emission peak obtained in PL study validates the presence of oxygen vacancies in the prepared samples. From the UV-DRS study, band gap of the samples were found to decrease with increase in doping concentration. The gas sensing ability of the prepared samples has been done by an exposure of different reducing gases (ammonia, ethanol, formaldehyde, acetone and xylene) at different temperatures and various gas concentrations. The response and recovery time of the samples are also assessed. From the data, it has been found that all the films shows better response towards ammonia. It has been found that 15% of Cu-ZrO2 sensor showed higher sensitivity (43.18%), faster response (60 s) and recovery time (60 s) among all the samples which proves that the addition of Cu boosted up the gas sensing nature of ZrO2 nano structure.

Synergistic catalysis over hollow CeO2-CaO-ZrO2 nanostructure for polycarbonate methanolysis with methanol

Herein, CeO2-CaO nanoparticle coated on hollow ZrO2 nanostructure (denoted as CeO2-CaO-ZrO2) was prepared via a template impregnation method, which showed excellent catalytic performance for polycarbonate (PC) transesterification with methanol (named as methanolysis). The lattice oxygen (O2−) generated from the incorporation of CeO2 and CaO to ZrO2, adsorbed atomic oxygen (O−), or adsorbed molecular oxygen (O2−) generated from predominately via CeO2 serve as the active species to promote PC methanolysis. In order to explore the detailed synergistic effect of different components and the influence of structure tailor, the mesoporous CaO-Al2O3 was also investigated and compared with hollow CeO2-CaO-ZrO2. CeO2 plays an important role in the storage and release of oxygen and forms stronger O2−/O−/O2− basic sites. Notably, interfacial active species (electron-enriched O2−/O−/O2− sites) participate in stripping protons from CH3OH which is the rate determination step for PC methanolysis. Such interfacial sites of CeO2-CaO-ZrO2 catalyst serve as the optimal active site with the substantially declined activation energy barrier (∼0.31 eV) for stripping protons from CH3OH in contrast to that of 0.83 eV of CaO-Al2O3. The activation energy is considerably declined due to the interfacial synergistic component catalysis and abundant activation sites over hollow structure. The PC conversion over such hollow CeO2-CaO-ZrO2 achieved almost 100% under the conditions of temperature 100 °C, m(cat):m(PC) = 0.05:1, n(methanol):n(PC) = 8:1 and time 2 h, while the conversion was only 13.4% over CaO-Al2O3 under the same conditions. The hollow CeO2-CaO-ZrO2 catalyst could be reused for 5 times without obvious decrease in PC conversion and BPA yield. This work supplies an extended understanding on interfacial synergistic catalysis toward PC methanolysis, which is important for efficient design and building of heterogeneous catalysts with higher activity.

First-principles studies on mechanical properties and band structures of TMO2 (TM = Zr or Hf) nanostructures under high pressure

The mechanical and band structure studies of TMO2 (TM = Zr or Hf) nanostructures under high pressure in the range of 0 GPa and 50 GPa is studied using density functional theory. Upon applying the pressure, the unit cell size decreases for TMO2 nanostructures. The Young's and bulk modulii of TMO2 decreases until 30 GPa and then increases up to 50 GPa. The universal anisotropy increases with the increase in the pressure. The ZrO2 and HfO2 nanostructure turns from ductile to brittle nature for the applied pressure beyond 30 GPa, which is inferred from Pugh's criterion. The band gap of TMO2 increases with the increase in the applied pressure. The findings show the various transformations of TMO2 nanostructures under high pressure, which can be used for tailoring the band gap and mechanical properties of TMO2 nanomaterials.

Formation of zirconia precursor nanoplates mediated by ionic liquid and transformation to monoclinic ZrO2 nanostructures

AbstractThe [Zr(OH)5]− imidazolium complex was used to synthesize a zirconia precursor with plate-like nanostructue hydrolyzed under strong acid conditions, which was characterized by means of powder X-ray diffraction, thermogravimetric-differential scanning calorimetry, Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis, inductively coupled plasma and electronic differential system. The zirconia precursor can be transformed to monoclinic ZrO2 by annealing at a temperature above 400 °C. With the increasing of the curing temperature, it tended to give rise to porous ZrO2 nanostructures.

Template‐Free Synthesis of Star‐Like ZrO2 Nanostructures and Their Application in Photocatalysis

Star‐like nano‐ZrO2 has been synthesized using Zr(NO3)4·5H2O as zirconium source by a hydrothermal process without any template and surfactant. The structure of the as‐prepared ZrO2 powder was investigated by multiple advanced analytical methods. The results showed that CH3COO− and NO3− had great effects on the formation of star‐like ZrO2 nanostructures. The as‐prepared ZrO2 had a superior catalytic activity, and the reason for it was analyzed by UV‐Vis diffuse reflectance spectroscopy. The effect of raw material ratios on the photocatalytic property of ZrO2 was studied. The synthesized ZrO2 showed a narrow bandgap (3.50–3.85 eV) and an excellent photocatalytic activity, and the degradation of RhB was up to nearly 100% in 30 min with this photocatalyst.

Co-occurrence of linear and circular dichroism in chiral sculptured ZrO2 thin films

Three dimensional chiral metamaterials, have unique helical shaped morphologies and periodically varying permittivity, possess inherent fascinatingly chiroptical activity in developing potential photonic applications. Herein, we demonstrate a systemic simulations of optical activity in chiral sculptured thin films (CSTFs) made of ZrO2. In particular, a circular dichroism (CD) and linear dichroism (LD) are scrutinized for the proposed ZrO2 CSTFs. From the calculated differential absorption, LD and CD spectrum is computed using linear and circular polarized light beams respectively. The signated mode of different peaks for LD and CD is observed at different sweep angles with a large LD effect. Moreover, the CD diminishes at large sweep angle. This finding strongly indicates high potential of our proposed helical ZrO2 nanostructures as a perfect polarization converter. Simultaneously, optical remittance of different helical nanostructures are also compared.

Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV–visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

Effect of Various Ionic Surfactants Mediated ZrO2 Nanostructures and Their Structural, Morphological and Optical Properties Under UV Irradiation

Structural, compositional, morphological, optical and photocatalytic activity of ZrO2 nanostructures were investigated via co-precipitation method (CPM) using various surfactants such as, polysorbate-80 (non-ionic), CTAB (cationic), SDS (anionic). The synthesized samples were characterized by the powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED) and Ultraviolet–Visible Spectroscopy (UV–Visible) studies. The crystal structure, diffraction planes, peak broadening, crystallite size and lattice strain were observed for the ZrO2 samples using PXRD. The functional groups were identified by the FTIR studies. The different morphologies were predicted from the SEM studies, such as spherical (Polysorbate-80), hexagonal (CTAB) and nanorod (SDS), respectively. The absorption spectra were presented in UV region and the optical bandgap energies were found to be 3.67 (P-80), 4.05 (CTAB) and 4.42 eV (SDS), respectively. The degradation process of CTAB and SDS mediated ZrO2 samples were comparatively investigated under UV illumination. In addition, the photocatalytic mechanism is also studied.

Mesoporous ZrO2 Nanoframes for Biomass Upgrading

The rational design and preparation of a high-performance catalyst for biomass upgrading are of great significance and remain a great challenge. In this work, mesoporous ZrO2 nanoframe, hollow ring, sphere, and core-shell nanostructures have been developed through a surfactant-free route for upgrading biomass acids into liquid alkane fuels. The obtained ZrO2 nanostructures possess well-defined hollow features, high surface areas, and mesopores. The diversity of the resultant ZrO2 nanostructures should arise from the discrepant hydrolysis of two different ligands in zirconocene dichloride (Cp2ZrCl2) as the zirconium precursor. The time-dependent experiments indicate that Ostwald ripening and salt-crystal-template formation mechanisms should account for hollow spheres and nanoframes, respectively. Impressively, compared with the hollow sphere, commercial nanoparticle, and the ever-reported typical results, the ZrO2 nanoframe-promoted Ni catalyst exhibits greatly enhanced catalytic activity in the upgrading of biomass acids to liquid alkane fuels, which should be ascribed to the hollow feature, large active surface area, highly dispersed Ni, and strong metal-support interactions arising from the structural advantages of nanoframes. The nanoframes also possess excellent solvothermal and thermal stability. Our findings here can be expected to offer new perspectives in material chemistry and ZrO2-based catalytic and other applications.

Synthesis, characterization and electrochemical analysis of hydrothermal synthesized AgO incorporated ZrO2 nanostructures

AgO nanospheres incorporated ZrO2 nanocubes were obtained in a novel two stage biochemical assisted hydrothermal route. Firstly, the ZrO2 nanocubes were obtained using the extracted biochemical from Streptomyces sp. then in the identical strategy AgO nanospheres were incorporated on the surfaces of the nanocubes. The obtained nanostructures were characterized systematically for structural, elemental, morphological, optical and electrochemical behaviors. The electron microscopic images indicated the cubic shaped ZrO2 particles of 400–600 nm size, whereas the surface incorporated AgO nanosphere had exhibited ~30 nm size. The FT-IR spectrum taken for the nanostructures indicated the biochemical process assisted formation of nanomaterials. The optical bandgap of the ZrO2 nanocubes and AgO incorporated ZrO2 nanocubes were evaluated as 4.92 and 3.33 eV, respectively. Also, the quenching observed in the emission spectrum showed a little evidence of electron transition occurs in the interface between the materials. Further, the analyzed electrochemical studies confirmed that the enhancement of electric conduction of ZrO2 has been made by incorporating the AgO nanospheres.

Defect-Rich Dopant-Free ZrO2 Nanostructures with Superior Dilute Ferromagnetic Semiconductor Properties.

Control of the spin degree of freedom of an electron has brought about a new era in spin-based applications, particularly spin-based electronics, with the potential to outperform the traditional charge-based semiconductor technology for data storage and information processing. However, the realization of functional spin-based devices for information processing remains elusive due to several fundamental challenges such as the low Curie temperature of group III-V and II-VI semiconductors (<200 K), and the low spin-injection efficiencies of existing III-V, II-VI, and transparent conductive oxide semiconductors in a multilayer device structure, which are caused by precipitation and migration of dopants from the host layer to the adjacent layers. Here, we use catalyst-assisted pulsed laser deposition to grow, for the first time, oxygen vacancy defect-rich, dopant-free ZrO2 nanostructures with high TC (700 K) and high magnetization (5.9 emu/g). The observed magnetization is significantly greater than both doped and defect-rich transparent conductive oxide nanomaterials reported to date. We also provide the first experimental evidence that it is the amounts and types of oxygen vacancy defects in, and not the phase of ZrO2 that control the ferromagnetic order in undoped ZrO2 nanostructures. To explain the origin of ferromagnetism in these ZrO2 nanostructures, we hypothesize a new defect-induced bound polaron model, which is generally applicable to other defect-rich, dopant-free transparent conductive oxide nanostructures. These results provide new insights into magnetic ordering in undoped dilute ferromagnetic semiconductor oxides and contribute to the design of exotic magnetic and novel multifunctional materials.