Composite solid electrolyte based on (Ca2+, Al3+)-infiltrated ZrO2(MgO) for direct sulfur determination in the liquid iron

Magnesium-stabilized zirconia [ZrO₂(MgO)] with calcium aluminate (CaO–Al₂O₃) ceramic composite electrolyte based on (calcium ion [Ca²⁺], aluminum ion [Al³⁺])-infiltrated zirconia-magnesia [ZrO₂(MgO)] porous backbone was prepared for direct sulfur ([S]) determination in the liquid iron. Effect of amylum content on the phase composition, microstructures and mechanical properties of the composite electrolyte was detected and correlated to the electrochemical performance. The results indicated that the ZrO₂(MgO)-(CaO–Al₂O₃) composite electrolyte simultaneously inherited the mechanical and electrochemical properties of ZrO₂(MgO), and unique physical and chemical properties of CaO–Al₂O₃. The compressive strength of the composite electrolyte reached above 250 MPa and the conductivity reached up to 0.003 S/cm^-, meeting the requirements of the sensor for the electrolyte. The assembled sensor could respond to sulfur activity and showed fine response characteristics. Among the tested compositions, the composite electrolyte with 6.0 wt% of amylum added in ZrO₂(MgO) porous backbone exhibited the best properties and was more suitable for application in sulfur determination.     

Hydrogen Production by Steam Reforming of Ethanol Over Mesoporous Ni–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZrO<Subscript>2</Subscript> Catalysts

This review paper reports the recent progress concerning the application of nickel–alumina–zirconia based catalysts to the ethanol steam reforming for hydrogen production. Several series of mesoporous nickel–alumina–zirconia based catalysts were prepared by an epoxide-initiated sol–gel method. The first series comprised Ni–Al₂O₃–ZrO₂ xerogel catalysts with diverse Zr/Al molar ratios. Chemical species maintained a well-dispersed state, while catalyst acidity decreased with increasing Zr/Al molar ratio. An optimal amount of Zr (Zr/Al molar ratio of 0.2) was required to achieve the highest hydrogen yield. In the second series, Ni–Al₂O₃–ZrO₂ xerogel catalysts with different Ni content were examined. Reducibility and nickel surface area of the catalysts could be modulated by changing nickel content. Ni–Al₂O₃–ZrO₂ catalyst with 15 wt% of nickel content showed the highest nickel surface area and the best catalytic performance. In the catalysts where copper was introduced as an additive (Cu–Ni–Al₂O₃–ZrO₂), it was found that nickel dispersion, nickel surface area, and ethanol adsorption capacity were enhanced at an appropriate amount of copper introduction, leading to a promising catalytic activity. Ni–Sr–Al₂O₃–ZrO₂ catalysts prepared by changing drying method were tested as well. Textural properties of Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst produced from supercritical drying were enhanced when compared to those of xerogel catalyst produced from conventional drying. Nickel dispersion and nickel surface area were higher on Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst, which led to higher hydrogen yield and catalyst stability over Ni–Sr–Al₂O₃–ZrO₂ aerogel catalyst.     

Silica-Zirconia Coatings Produced by Dipping and EPD from Colloidal Sol–Gel Suspensions

SiO₂-ZrO₂ sols have been prepared via acid catalysis using a commercial colloidal suspension of zirconia and two silica alkoxides; tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES). Suspensions with 10, 15 and 25-mol% of ZrO₂ were prepared. The stability of the suspensions was followed by rheological measurements showing that the amount of water incorporated with the colloidal suspension is the factor that limits the maximum ZrO₂ content. Coatings have been prepared by dipping using the suspensions up to 25-mol% ZrO₂ onto glass-slides at different withdrawal rates. EPD process has been used to prepare coatings onto stainless steel AISI 304 using the suspension with 25-mol% ZrO₂ at different pHs. The parameters associated with the EPD process (current density, electric field, potential and deposition time) have been evaluated. The critical thickness for a ZrO₂ addition of 25-mol% was 0.8 μm and it increased for diminishing ZrO₂ content.     

Spinel LiNi0.5Mn1.5O4 with ultra-thin Al2O3 coating for Li-ion batteries: investigation of improved cycling performance at elevated temperature

In this study, spinel LiNi_0.5Mn_1.5O₄ (LNMO) was successfully decorated with Al₂O₃ thin film by using atomic layer deposition (ALD) approach and evaluated as a cathode material for high-temperature applications in lithium ion batteries (LIBs). To optimize the LNMO-Al₂O₃ electrodes operated at elevated temperature (55 °C), the effects of Al₂O₃ thicknesses adjusted by controlling the ALD deposition cycle were systemically investigated. According to the series of electrochemical results, the LNMO coated with the Al₂O₃ thin layer in the thickness of ca. 2 nm was achieved by using one-cycle ALD and the LNMO-Al₂O₃ electrode exhibited superior electrochemical stability (capacity retention up to 93.7% after consecutive 150 charge/discharge cycles at 0.5 C to the pristine LNMO electrode at elevated temperature. This can be attributed to two factors: (i) the decoration of Al₂O₃ thin layer could not contribute remarkably to extra resistance for charge transfer; (ii) Al₂O₃ thin film deposition could efficiently stabilize the growth of cathode electrolyte interface (CEI) and suppress the dissolution of transition metals. Therefore, these results verify that the LNMO-Al₂O₃ electrode could be regarded as a promising cathode material for high-voltage LIBs, especially at elevated temperature operation.

     

Comparative analysis of the composition, structure, and catalytic activity of the NiO-CuO-TiO2 on Titanium and NiO-CuO-Al2O3 on aluminum composites

The catalytically active oxide structures based on Al and Ti prepared by plasma-electrolytic oxidation (PEO) and additionally modified by impregnation with an aqueous solution of nickel and copper nitrates followed by annealing were studied. The oxide film-metal composites were studied using X-ray diffraction and X-ray spectroscopic analysis, X-ray electron spectroscopy, and electron microscopy. The catalytic activity of the composites in the reaction of CO oxidation was studied. In spite of differences in the elemental composition and morphology, the initial oxide layers on Al and Ti were comparable in terms of activity. Microgranules of size ～ 1 µm and formations from tens to hundreds of nanometers in size were detected on the surface of PEO layers. The modified layers contained crystalline CuO, NiO, and Al₂O₃ or TiO₂ phases. The surface layers of the modified structures about 3 nm in thickness on AMg5 aluminum alloy and VT1-0 titanium had the same elemental composition but exhibited different activity in the reaction of CO oxidation to CO₂.     

Eliminated Phototoxicity of TiO2 Particles by an Atomic‐Layer‐Deposited Al2O3 Coating Layer for UV‐Protection Applications

We demonstrate the conformal coating of an ultrathin Al₂O₃ layer on TiO₂ nanoparticles through atomic layer deposition by using a specifically designed rotary reactor to eliminate the phototoxicity of the particles for cosmetic use. The ALD reactor is modified to improve the coating efficiency as well as the agitation of the particles for conformal coating. Elemental and microstructural analyses show that ultrathin Al₂O₃ layers are conformally deposited on the TiO₂ nanoparticles with a controlled thickness. Rhodamine B dye molecules on Al₂O₃‐coated TiO₂ exhibited a long life time under UV irradiation, that is, more than 2 h, compared to that on bare TiO₂, that is, 8 min, indicating mitigation of photocatalytic activity by the coated layer. The effect of carbon impurities in the film resulting from various deposition temperatures and thicknesses of the Al₂O₃ layer on the photocatalytic activity are also thoroughly investigated with controlled experimental condition by using dye molecules on the surface. Our results reveal that an increased carbon impurity resulting from a low processing temperature provides a charge conduction path and generates reactive oxygen species causing the degradation of dye molecule. A thin coated layer, that is, less than 3 nm, also induced the tunneling of electrons and holes to the surface, hence oxidizing dye molecules. Furthermore, the introduction of an Al₂O₃ layer on TiO₂ improves the light trapping thus, enhances the UV absorption.     

Effect of ZrO<Subscript>2</Subscript> on Catalyst Structure and Catalytic Sulfur-Resistant Methanation Performance of MoO<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

A series of MoO₃/ZrO₂–Al₂O₃ catalysts was prepared and investigated in the sulfur-resistant methanation aimed at production of synthetic natural gas. Different methods including impregnation, deposition precipitation, and co-precipitation were used for preparing ZrO₂–Al₂O₃ composite supports. These composite supports and their corresponding Mo-based catalysts were investigated in the sulfur-resistant methanation, and characterized by N₂ adsorption–desorption, XRD and H₂-TPR. The results indicated that adding ZrO₂ promoted MoO3dispersion and decreased the interaction between Mo species and support in the MoO₃/ZrO₂–Al₂O₃ catalysts. The co-precipitation method was favorable for obtaining smaller ZrO₂ particle size and improving textural properties of support, such as better MoO₃ dispersion and increased concentration of Mo⁶⁺ species in octahedral coordination to oxygen. It was found that the MoO₃/ZrO₂–Al₂O₃ catalyst with ZrO₂Al₂O₃ composite support prepared by co-precipitation method exhibited the best catalytic activity. The ZrO₂ content in the ZrO₂Al₂O₃ composite support was further optimized. The MoO₃/ZrO₂–Al₂O₃ with 15 wt % ZrO₂ loading exhibited the highest sulfur-resistant CO methanation activity, and excess ZrO₂ reduced the specific surface area and enhanced the interaction between Mo species and support. The N₂ adsorption-desorption results indicated that the presence of ZrO₂ in excessive amounts decreased the specific surface area since some amounts of ZrO₂ form aggregates on the surface of the support. The XRD and H₂-TPR results showed that with the increasing ZrO₂ content, ZrO₂ particle size increased. These led to the formation of coordinated tetrahedrally Mo⁶⁺(T) species and crystalline MoO₃, and this development was unfavorable for improving the sulfur-resistant methanation performance of MoO₃/ZrO₂–Al₂O₃ catalyst.     

Mechanical Properties of Electrostatically Self-Assembled Al2O3–ZrO2 Nanocomposites Prepared at Room Temperature

Alternate layers of Al₂O₃ and ZrO₂ nanocomposite films were prepared on silicon wafers and glass substrates at room temperature using the electrostatic self-assembly monolayer (ESAM) process. The versatile approach of the ESAM process provides the possibility of integrating diverse inorganic colloids on the nanosize level in a layer-by-layer or block-by-block fashion. Further, it allows the combination of inorganic colloids and organic molecules, making it possible to fabricate thick films with large pores and good stress relaxation. Highly ordered, micron-thick films have been formed, sintered, and characterized by scanning electron microscopy and ellipsometry. There is no significant visible crack formation for Al₂O₃–ZrO₂ composite films after heat treatment at 1200°C for 2 h, although significant thickness reduction occurs. The hardness and Young's modulus of these films before and after sintering were measured using nanoindentation techniques.     

Reaction-Induced Metal-Metal Oxide Interactions in Pd-In2O3/ZrO2 Catalysts Drive Selective and Stable CO2 Hydrogenation to Methanol

Ternary Pd-In₂O₃/ZrO₂ catalysts exhibit technological potential for CO₂-based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In₂O₃/ZrO₂ systems prepared by wet impregnation evolves under CO₂ hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPd_x alloy particles decorated by InO_x layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO₂ hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation.     

(ZrO2)0.86(Sm2O3)0.14纳米粉体的水热法合成及其烧结体的电性能

以湿化学法制得Zr(OH)₄和Sm(OH)₃的共沉淀为前驱体, 在碱性介质中用水热法合成了(ZrO₂)_0.86(Sm₂O₃)_0.14及(ZrO₂)_0.88(Sm₂O₃)_0.12纳米粉体. 将纳米粉体在较低温度(1450 ℃)下烧结制得了致密的固体电解质陶瓷样品, 比通常高温固相反应法采用的烧结温度(＞1600 ℃)降低了150 ℃以上. XRD测定结果表明, (ZrO₂)_0.86(Sm₂O₃)_0.14纳米粉体及其烧结体均为立方相, 但(ZrO₂)_0.88(Sm₂O₃)_0.12纳米粉体为立方相, 它的烧结体为立方相和单斜相的混合相. 用交流阻抗谱法、氧浓差电池法及氧泵(氧的电化学透过)法研究了(ZrO₂)_0.86(Sm₂O₃)_0.14陶瓷样品在600～1000 ℃下的离子导电特性. 结果表明, 该陶瓷样品在600～1000 ℃下氧离子迁移数为1, 氧离子电导率的最大值为3.2×10^－2 S•cm^－1, 是一个优良的氧离子导体; 它的氧泵性能明显地优于YSZ.     

Influence of ZrO2 on Carbon Monoxide Oxidation Over Pd/Al2O3

The influence of ZrO₂ on the properties of Al₂O₃ and performances of Pd/Al₂O₃ catalyst in CO oxidation have been investigated. TPD results show that the activity enhanced is due to the increase of the adsorptive capacity of CO and the activation of C=O bond after the introduction of ZrO₂.     

ZrO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> binary oxides as promising supports for palladium catalysts of hydrodechlorination

Deposited palladium catalysts of the hydrodechlorination of 1,3,5-trichlorobenzene were studied. Pure zirconium and aluminum oxides and ZrO₂-Al₂O₃ mixtures with 1, 5, and 10 mol % Al₂O₃ prepared by coprecipitation were used as supports. Palladium was deposited by the precipitation of its hydroxide on supports. Catalysts on binary supports (ZrO₂ + 1% Al₂O₃ and ZrO₂ + 5% Al₂O₃) exhibited higher activity and stability in hydrodechlorination compared with catalysts on pure supports. The suggestion was made that the high activity and stability of these systems in hydrodechlorination was related to the formation of binary oxide in the interaction of ZrO₂ with palladium oxide at the stage of annealing of the catalyst precursor. Binary oxide, which was a center of the activation of the C-Cl bond, was simultaneously a source of active hydrogen. The presence of various palladium states in catalysts was substantiated by the temperature programmed reduction method.     

Enhanced epoxidation of soybean oil by novel Al2O3–ZrO2–TiO2 solid acid catalyst

This study aims to develop highly efficient, recyclable solid catalysts for the epoxidation of vegetable oils. An Al₂O₃–ZrO₂–TiO₂ solid acid catalyst was prepared by a co‐precipitation/impregnation method and characterised through scanning electron microscopy, energy‐dispersive spectroscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared and nitrogen adsorption–desorption analyses. The solid acid catalyst with a high surface area and typical slit pore adsorption was successfully synthesised. Al₂O₃–ZrO₂–TiO₂ also exhibits high stability and improved catalytic efficiency in the epoxidation of soybean oil. An oil conversion rate of 86.6%, which is higher than that of conventional catalysts, was obtained with a catalyst loading of 0.8 wt% and was maintained at 76.6% even after recycling the catalyst three times. The performance of the solid catalyst was slightly superior to that of H₂SO₄. Therefore, this novel catalyst may potentially be applicable in catalysing soybean oil epoxidation.     

Comparison of the quantity and reactivity of carbon deposit arising on Mo/Al2O3 and Mo/ZrO2 catalysts

The quantity and reactivity of carbon deposit arising on Mo/Al₂O₃ and Mo/ZrO₂ catalysts in propane decomposition was investigated. Results showed that the Mo/ZrO₂ catalyst is more resistant to carbon deposit formation process. The coke formed on the surface of this catalyst is more reactive in oxygen atmosphere than the carbon deposit formed under the same conditions on Mo/Al₂O₃. This revised version was published online in June 2006 with corrections to the Cover Date.     

Formation of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–TiO<Subscript>2</Subscript> bilayer using atomic layer deposition and its application to dynamic random access memory

To enhance film conformality together with electrical property suitable for dynamic random access memory (DRAM) capacitor dielectric, the effects of oxidant and post heat treatment were investigated on aluminum and titanium oxide (Al₂O₃–TiO₂) bilayer (ATO) thin film formed by atomic layer deposition method. For the conformal deposition of Al₂O₃ thin film, the O₃ oxidant required a higher deposition temperature, more than 450 °C, while H₂O or combined oxygen sources (H₂O+O₃) needed a wide range of deposition temperatures ranging from 250 to 450 °C. Conformal deposition of the TiO₂ thin film was achieved at around 325 °C regardless of the oxidants. The charge storage capacitance, measured from the ATO bilayer (4 nm Al₂O₃ and 2 nm TiO₂) deposited at 450 °C for Al₂O₃ and 325 °C for TiO₂ with O₃ oxidant on the phosphine-doped poly silicon trench, showed about 15% higher value than that of 5 nm Al₂O₃ single layer thin film without any increase of leakage current. To maintain the improved electrical property of the ATO bilayer for DRAM application, such as enhanced charge capacitance without increase of leakage current, upper electrode materials and post heat treatments after electrode formation must be selected carefully. Dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday.     

Synthesis of a precursor for an alumina ceramic reinforced by zirconium dioxide from inorganic compounds in the presence of urea

Samples of a precursor for an alumina ceramic reinforced by zirconium dioxide were synthesized. The samples have a uniform structure and are characterized by high ratios of the tetragonal and monoclinic modifications of ZrO₂, tlm, after a thermal treatment (1250°C). The structure of samples in the system Al₂O₃-ZrO₂ is formed under conditions favorable for deposition of products of hydrolysis of Al(III) ions on the surface of ZrO₂ sol particles in decomposition of urea. The coating of ZrO₂ sol particles by products of hydrolysis of Al(III) salts was confirmed by electrophoresis. The size distribution of particles of the in?dividual ZrO₂ sol was determined by small-angle X-ray scattering. The structure of the products formed in thermal treatment of samples of mixed oxides Al₂O₃-ZrO₂ was characterized by X-ray phase analysis and scanning electron microscopy. The porosity and specific surface area of a thermally treated sample was determined by measuring nitrogen absorption isotherms.     

Catalytically Promoted NOx Sorption by ZrO2-Based Oxides

Metal promoted zirconia-based oxide sorbents, such as Pt–ZrO₂/Al₂O₃ for NO _x have been investigated. To clarify the role of the catalyst component, sorption of NO and NO₂ was compared using the samples with and without Pt. The catalytic oxidation of NO to NO₂ and successively to nitrate ions is an important role for the Pt catalyst. The experimental results indicate that a high-temperature calcination is essential to remove residual Cl from Pt–ZrO₂–Al₂O₃ prepared from H₂PtCl₆ in order to provide more active NO _x sorption sites. Of M–ZrO₂–Al₂O₃ samples investigated, ruthenium as well as Pt demonstrated relatively good performance as a catalyst component in the sorbent. The FT-IR spectra after sorption of NO and NO₂ demonstrated a strong band attributed to stored nitrate ions. The Pt catalyst was more resistant to sulfur poisoning than a base metal catalyst. However, the NO _x sorptive capacities of the Pt–ZrO₂/Al₂O₃ sorbents were expected to be deteriorated in dilute SO₂ as far as observed from FT-IR spectra.     

Contribution to the analytical characterization of coatings produced by thermal spraying

This paper reports on the use of Auger electron spectroscopy (AES)/ depth profile analysis for the investigation of plasma-sprayed coatings. Prior to spraying the St 37 substrates are heated to 300 °C or 500 °C for ceramic or metallic layers, respectively. Studies of the starting materials and of the interfaces are important if the adhesion mechanism is to be understood. Therefore the initial components—the unheated and heated substrates and the powder particles NiCrAl, Al₂O₃ and ZrO₂-7.25Y₂O₃—are analyzed. Depth profiles obtained from two coatings St 37/NiCrAl and St 37/Al₂O₃ show the influence of plasmaspraying on substrate surfaces and sprayed particles. Plasma-spraying mainly causes a decrease of superficial carbon contamination for both coating layers. In the case of St 37/NiCrAl incorporation of carbon in the sprayed layer is observed. The whole layer is almost completely oxidized except for some areas where substrate and particle material are present. It is assumed that these areas are identical with so-called adherence zones.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

致密的5%Al3+掺杂的SnP2O7-SnO2复合陶瓷在中温燃料电池中的应用

首先制备了未掺杂和5%(摩尔分数)Al³⁺掺杂SnO₂的多孔性基片, 然后将基片与85%的H₃PO₄在600℃下反应, 分别得到了致密的未掺杂和5%Al³⁺掺杂的SnP₂O₇-SnO₂复合陶瓷样品. 采用X射线衍射(XRD), 扫描电子显微镜(SEM)和X射线能量色散谱(EDS)测试方法对样品进行了表征, 采用电化学阻抗谱法(EIS)测试了样品在中温(100-250℃)下, 湿润空气和湿润氢气气氛中的电导率. 结果表明, 在湿润空气和湿润氢气中, 5%Al³⁺掺杂的SnP₂O₇-SnO₂复合陶瓷样品的电导率均高于未掺杂的SnP₂O₇-SnO₂复合陶瓷样品的电导率, 且该复合陶瓷样品在湿润空气和湿润氢气中250℃下, 电导率分别达到最大值: 4.30×10^-2和6.25×10^-2 S·cm^-1, 高于至今报道的SnP₂O₇-SnO₂基复合陶瓷及SnP₂O₇基陶瓷在类似条件下的电导率. 以5%Al³⁺掺杂的SnP₂O₇-SnO₂复合陶瓷样品(厚度: 1.45 mm)为电解质, 多孔性铂为电极组装成的氢气/空气燃料电池具有良好的中温电池性能, 175、200、250℃的最大输出功率密度分别为52.0、61.9、82.3 mW·cm^-2. 良好的中温电池性能与该复合陶瓷电解质较高的电导率和致密度及该燃料电池较低的界面极化电阻有关.     

AN XPS study of the interaction of model Ba/TiO2 AND Ba/ZrO2 NSR catalysts with NO2

X-ray photoelectron spectroscopy is used to study the interaction of model NO₂ storage-reduction catalysts (NSR catalysts) Ba/TiO₂ and Ba/ZrO₂ with NO₂. The catalysts are prepared on the surface of ultrathin Al₂O₃ film substrates obtained by the FeCrAl alloy oxidation. It is shown that at room temperature the model catalysts react with NO₂ with the successive formation of surface barium nitrite and nitrate. The NO₂ reduction with the formation of barium nitrite at the initial step of the interaction is assumed to be accompanied by the oxidation of residual metallic barium and amorphous carbon impurity. It is found that the formation of barium nitrate proceeds more efficiently on Ba/ZrO₂ rather than on Ba/TiO₂.