Amount Of MoO3 Research Articles

Effect of niobium on the mechanical strength of the laser beam welding joints of molybdenum

The low strength and plasticity of molybdenum (Mo) fusion welding joints are the key problem hindering the application in the engineering structures field. The main reason for the low strength and plasticity of Mo joints is the low grain boundary bonding strength, which is also known as grain boundary brittleness. The segregation of oxygen (O) at the grain boundaries and the distribution of the lamellar MoO2 phases are the intrinsic reasons for brittleness. In this study, the Mo fusion welding joints were processed by laser beam welding. The maximum tensile strength of the unalloyed joint could only reach 169.8 MPa. Meanwhile, the maximum tensile strength of joints with Nb alloyed could reach 426.7 MPa. During the welding, the niobium (Nb) element preferred to reduce the O content and realize the second-phase strengthening at the grain boundaries. The results of XPS and TEM confirmed that Nb mainly existed in the form of Nb2O5 and NbC in the fusion zone (FZ) of joints with Nb alloyed. The SEM and EBSD showed that a certain amount of NbC is precipitated at the grain boundaries, and the amount of MoO2 is significantly reduced. The lamellar MoO2 could be clearly observed on the grain boundary surface of the FZ of the joints without alloying.

Effect of MoO3 on Na2O–B2O3–CdO–ZnO glasses: Applications in optoelectronics, communication devices, and radiation shielding

The current study focuses on the physical and structural aspects of B2O3–CdO–ZnO–Na2O glasses that have been reinforced by MoO3 ions. The samples were experimentally prepared using a melt quenching procedure, and then the absence of strong peaks in the XRD spectra confirms their amorphous nature. A variety of optical, Raman, and radiationshielding qualities were evaluated and described. The structural changes in the material were investigated using FTIR and Raman spectra. The density of the samples rose when MoO3 was added, implying that BO3 was transformed into BO4 units. The transition of Mo6+ to Mo5+ ions is responsible for the reduction in band gap in these glasses. Because of the vacancy generated by the oxygen units, the Urbach energy increased, implying the generation of additional defects. The presence of diverse structures present in the structure of the glass was revealed by FTIR and Raman spectra, such as MoO6, BO3, BO4, metaborates, pyroborates, and so on. The transition of BO3 to BO4 units, which is crucial in density analyses, was also corroborated by Raman spectra. Using FLUKA simulation and XCOM estimations, the mass attenuation coefficient of the glasses improved with the amount of MoO3. At 15 keV, the half-value layer of 0.0103 cm, 0.01019 cm, 0.01016 cm, 0.0101 cm, and 0.01005 cm was obtained for glasses with an MoO3 concentration of 0, 0.5, 1, 1.5, and 2.0 mol% respectively. The optimum MoO3 concentration for fast and thermal neutron cross-sections was 0.5 and 2.0 mol% respectively. The glasses are viable materials for environmentally friendly and transparent radiation barriers in nuclear facilities.

A novel coating method for MoO3 to improve the electrochemical performance of regenerated Li(Ni0.8Co0.1Mn0.1)O2 cathode material from spent Li‐ion Batteries

AbstractRegeneration of cathode materials from spent lithium‐ion batteries (LIBs), as an efficient short‐range recycling strategy, is gradually becoming a research hotspot. However, due to the unavoidable influence of impurities in the recycling process, the regenerated material suffers from severe performance degradation during the recycling process. Surface coating is an effective routine to improve cycling stability. Here, regenerated Li(Ni0.8Co0.1Mn0.1)O2 cathode material is successfully wet‐coated by an appropriate amount of MoO3. The study finds the material loading 2.0 wt% MoO3 exhibits even better properties. After 100 cycles, the capacity retention efficiency is significantly improved from 70 % to 86.5 % in the range of 2.8∼4.3 V. It is confirmed that the MoO3 coating effectively stabilized the cathode/electrolyte interface, thus reducing the occurrence of side reactions and improving the electrochemical stability of the battery. In addition, the MoO3 had great electrical conductivity, keeping the lithium diffusion even at a stable level upon cycling. To sum up, our work provides a simple and available modification strategy for nickel‐rich cathode materials recovered from spent LIBs.

MoO2 nanoparticles confined in N,P-codoped graphene aerogels with excellent pseudocapacitance performance

In this work, MoO2@NPGA nanocomposites were successfully prepared via a simple hydrothermal and calcination route. The as-prepared MoO2@NPGA composites exhibit a synergistic effect between MoO2 and N,P-codoped graphene aerogels, which can significantly improve the electrochemical performance of the MoO2@NPGA electrodes. Moreover, the results also proved that the mass loading of MoO2 has a huge effect on the electrochemical properties of MoO2@NPGA composites. With an appropriate amount of MoO2, the MoO2@NPGA composite shows a high specific capacitance (335 F g−1 at 1 A g−1) and excellent cycle stability (capacitance remains at 88% after 6000 cycles). Furthermore, the assembled symmetric supercapacitor displays a high energy density of 23.75 W h kg−1 at a power density of 300 W kg−1 and can maintain an energy density of 17.1 W h kg−1 when the power density reaches up to 6005 W kg−1.

Porous Molybdenum Carbide Nanostructures Synthesized on Carbon Cloth by CVD for Efficient Hydrogen Production.

Molybdenum carbide (Mo2 C) is a promising noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER), due to its structural and electronic merits, such as high conductivity, metallic band states and wide pH applicability. Here, a simple CVD process was developed for synthesis of a Mo2 C on carbon cloth (Mo2 C@CC) electrode with carbon cloth as carbon source and MoO3 as the Mo precursor. XRD, Raman, XPS and SEM results of Mo2 C@CC with different amounts of MoO3 and growth temperatures suggested a two-step synthetic mechanism, and porous Mo2 C nanostructures were obtained on carbon cloth with 50 mg MoO3 at 850 °C (Mo2 C-850(50)). With the merits of unique porous nanostructures, a low overpotential of 72 mV at current density of 10 mA cm-2 and a small Tafel slope of 52.8 mV dec-1 was achieved for Mo2 C-850(50) in 1.0 m KOH. The dual role of carbon cloth as electrode and carbon source resulted into intimate adhesion of Mo2 C on carbon cloth, offering fast electron transfer at the interface. Cyclic voltammetry measurements for 5000 cycles revealed that Mo2 C@CC had excellent electrochemical stability. This work provides a novel strategy for synthesizing Mo2 C and other efficient carbide electrocatalysts for HER and other applications, such as supercapacitors and lithium-ion batteries.

Hierarchical mesoporous MoO2 sphere as highly effective supercapacitor electrode

Abstract MoO 2 and MoO 3 with specific morphologies are synthesized on flexible carbon cloth through a facile hydrothermal method as supercapacitor electrodes. The prepared prismatic MoO 3 shows a specific capacitance of 54.7 F g −1 in 1 M LiOH electrolyte. Moreover, the prepared MoO 2 presents a spherical profile with hierarchical porous structure. Each MoO 2 sphere is stacked with several layers of MoO 2 “spindle” which is further built by amounts of MoO 2 nanoparticles. A high specific capacitance of 381.0 F g −1 is achieved for the MoO 2 sphere electrode, 7 times higher than that of MoO 3 .

Studies on modified borosilicate glass for enhancement of solubility of molybdenum

Molybdenum is a fission product with high fission yield, present in High Level Liquid Waste (HLW). Presently HLW is confined in borosilicate glass matrix. To enhance the solubility of MoO3, different host glass matrices containing different amount of MoO3 were prepared and studied. Phosphate containing borosilicate glass showed increased solubility for MoO3. X-ray Diffraction (XRD) studies were carried out to check for presence of crystalline phase within glass samples. Phosphate containing glass samples could accommodate 4 mol% of MoO3 whereas in absence of phosphate only 1 mol% of MoO3 could be accommodated in borosilicate glass. Laser induced breakdown spectroscopy (LIBS) data was employed to confirm the homogeneity of MoO3 within the glass sample. Glass transition temperature was also observed for all the glass samples to study the effect of MoO3 on thermal stability.

MoO2 nanoparticle-modified Li4Ti5O12 as high rate anode material for lithium ion batteries

Abstract MoO2 nanoparticle-modified Li4Ti5O12 materials were prepared via a facile solution-based method. X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) analyses revealed that the MoO2 nanoparticles were anchored on the surface of spinel Li4Ti5O12, and energy dispersive X-ray spectroscopy (EDX) mapping indicated the MoO2 nanoparticles distributed uniformly. Compared with the pristine Li4Ti5O12, the appropriate amount of MoO2 on the surface of the Li4Ti5O12 could not only effectively reduce the electrochemical polarization of Li4Ti5O12, but also contribute to specific capacity for lithium storage. The 3% MoO2 modified Li4Ti5O12 exhibited excellent rate capability of 116 mA h g−1 at 10 C, and superior cycling performance of 124 mA h g−1 after 450 cycles at 5 C. Since the MoO2 modification process was easy to handle and the source of Mo has affordable costs, MoO2-modified Li4Ti5O12 would be promising for industrial application.

Effects of Current Density on the Properties of Microarc Oxidation Coatings Formed on Aluminum Alloy in Silicate-Na<sub>2</sub>MoO<sub>4</sub> Electrolyte

Microarc oxidation (MAO) coatings on ZL108 aluminum alloy were prepared in the silicate-Na2MoO4 electrolytes with different current density. The MAO process was studied by measuring the voltage as a function of time. The microstructure, compositions, distribution of element and corrosion resistance of the MAO coatings were investigated by SEM, XRD, EDS, XPS and polarization curve, respectively. With the increasing of current density, the final voltage in the microarc discharge process increased. The results shown that the MAO coatings were mainly composed of mullite, γ-Al2O3, Si, little MoO2 and MoO3. The micropore size, thickness, compositions, distribution of element of the MAO coatings depended on the current density and the amount of MoO2 and MoO3. The corrosion resistance improved as the porosity of the MAO coatings decreasing.

Highly efficient MoO2.5(OH)0.5-doped ZnO nanoflower for photodecolorization of azo dye

Different morphologies of ZnO doped with 0–10 mol%. MoO2.5(OH)0.5 nanorod prepared by a simple solid-state reaction method with no template at room temperature, using zinc acetate, molybdenum oxide hydroxide and sodium hydroxide and used for photodecolorization of Congo red dye. The structural and optical properties of the samples were investigated using scanning electron microscopy, powder X-ray diffraction, UV–visible absorption, photoluminescence, FT-IR and Raman spectroscopy. It was found that, using different amount of MoO2.5(OH)0.5 not only prevent a drastic increase in the crystallite size of the zinc species but also provide suitable conditions for the oriented growth of primary nanoparticles. The abnormal Raman spectrum shows the strongest intensity at 438.5 cm−1, which indicates the wurtzite structure of ZnO is still maintained after doping of MoO2.5(OH)0.5. Furthermore, MoO2.5(OH)0.5-doped ZnO with morphology of flower exhibited a significant enhancement of photodecolorization capability toward Congo red dye after 20 min in UV exposure. The improvement of decolorization might be attributed to the crystallite size, especial morphology and composition of the nanostructures as result of doping ZnO with MoO2.5(OH)0.5.

Enhancement of red fluorescence and afterglow in CaWO4:Eu3+ by addition of MoO3

In this study, Eu3+ doped Ca(WO4)1−x(MoO4)x phosphors were synthesized via high temperature solid-state reaction. Compared with the Eu3+ activated CaWO4 sample, an increment of MoO3 doping concentration could improve the emission intensity. Improved red afterglow originating from the 5D0 to 7FJ (J=0, 1, 2, 3, 4) transitions of Eu3+ was observed after appropriate amount of MoO3 was added, and the optimal MoO3 doping concentration was experimentally determined to be 0.02. The proposed explanation for the afterglow property was also discussed.

ChemInform Abstract: The Acidic Property and Catalytic Activity of MoO3-SiO2-Al2O3.

The ternary oxide system MoO3–SiO2–Al2O3 was prepared by coprecipitation method. The pH of coprecipitation has been varied from pH=2 to pH=8 and its effect on the acidic properties of the ternary oxide acidic system was studied by butylamine titration. The MoO3–SiO2–Al2O3 prepared from highly acidic solution has low acid strength. The total acid amount of the ternary oxide decreased considerably at higher pH (>6) of coprecipitation. It was found that the total acid amount of MoO3–SiO2–Al2O3 containing 9.7% (by weight) of MoO3 and silica to alumina molar ratio 16.6 is very high compared with that of SiO2–Al2O3 of the same silica to alumina molar ratio. The acid strength of SiO2–Al2O3 is reduced by the incorporation of MoO3. Increase in calcination temperature increased the acid strength. The catalytic activity of MoO3–SiO2–Al2O3 was found to be very high for the alkylation of toluene with 2-propanol. The products are found to be o-cymene, p-cymene, and three isomers of diisopropyltoluenes. Reaction tempera...

1.4μm emission properties and local environments of Tm3+ ions in tellurite glass modified with MoO3

Abstract The 1.4 μm emission properties of Tm 3+ ions embedded in tellurite glass containing MoO 3 have been investigated in an effort to develop non-crystalline materials for ultra broadband optical amplifier. Spectral lineshape and bandwidth of the 1.4 μm emission exhibited a negligible dependence on amount of MoO 3 , while the measured lifetime of the Tm 3+ : 3 H 4 state decreased with increase in MoO 3 content. Multiphonon relaxation turned out to become stronger with increase in MoO 3 amount, which coincided with the further broadened Raman scattering bandwidth of the MoO 3 -containing tellurite glass. The spectroscopic properties of Tm 3+ ions doped in our modified tellurite glasses are discussed in connection with the local structural parameters obtained from Tm L 3 -edge EXAFS analysis.

Combustion Measurements of Fuel‐Rich Aluminum and Molybdenum Oxide Nano‐Composite Mixtures

AbstractFuel rich nano‐composite powders of aluminum and molybdenum oxide were tested for ignition and combustion behind the incident and reflected shock waves in a shock tube. The powders consisted of approximately 10 μm particles, each of which contained Al and MoO3 mixed by mechanical alloying on the nano‐scale. These powders were aluminum rich with composition ratios of 4 : 1, 8 : 1, and 16 : 1 Al : MoO3 by mass. Ignition tests were performed behind incident shocks for temperatures in the range of 900 to 1500 K. From these tests, ignition delay times were obtained, and some information on combustion duration was also derived. Samples were tested in air at 0.2 MPa, and compared against nano‐Al, 2.7 μm Al, and 10 μm Al baselines. Ignition results for the baseline Al cases were as expected: 10 μm Al not igniting until 2000 K, 2 μm Al igniting down to ∼1400 K, and n‐Al igniting as low as 1150 K. The thermite samples showed considerable improvement in ignition characteristics. At the lowest temperature tested (900 K), both the 8 : 1 and 4 : 1 samples ignited within 250 μs. The 16 : 1 sample (94% Al) ignited down to 1050 K – which represents an improvement of roughly 1000 K over baseline Al with only a small energetic penalty. In all cases, the ignition delay increased as the amount of MoO3 in the composite was reduced. The 4 : 1 nano‐composite material ignited as fast or faster than the n‐Al samples. Ignition delay increased with decreasing temperature, as expected. Emission spectra and temperature data were also taken for all samples using high‐speed pyrometry and time‐integrated spectroscopy. In these cases, measurements were made behind the reflected shock using end‐wall loading, though the conditions (temperature, pressure, and gas composition) were identical to the incident shock tests. Spectroscopy showed strong AlO features in all the samples, and the spectra fit well to an equilibrium temperature. Broadband, low resolution spectra were also fit to continuum, gray body temperatures. In general, the observed temperatures were reasonably close to 3500 K, which is similar to the combustion temperatures of pure aluminum under these conditions.

Desulfurization of Vacuum Gasoil by MCM-41 Supported Molybdenum−Nickel Catalysts

Hydrodesulfurization (HDS) of vacuum gas oil (VGO) was carried out in a trickle bed reactor at 400 °C and 7.2 MPa with a weight hourly space velocity (WHSV) = 2 h−1 over a series of molybdenum−nickel catalysts, which were prepared by loading the same amounts of MoO3 (12 wt %) and NiO (3 wt %) on supports including: tubular shaped MCM-41, nontubular shaped MCM-41, alumina, and silica. The HDS activity of the MoNi catalysts with different supports was investigated. The tubular shaped MCM-41, which possesses a regularly ordered molecular sieve structure, was shown to give significant improvements in the diffusion of large molecules. The results indicated that the tubular shaped MCM-41 supported catalyst has a higher activity than the other catalysts when measured over a 4−5 day running period. The effect of Si/Al ratios in the framework is also discussed. Various methods and techniques were used to characterize the catalysts such as: scanning electron microscopy (SEM), transmission electronic microscopy (TEM), temperature programming reduction (TPR), X-ray diffraction (XRD), mercury-porosity, and the generation of nitrogen adsorption−desorption isotherms.

Slurry Impregnation of ZrO2 Extrudates: Controlled EggShell Distribution of MoO3, Hydrodesulfurization Activity, Promotion by Co

Catalysts with eggshell/uniform Mo concentration profiles were prepared by a reaction of ZrO2 and ZrO(OH)2 extrudates with an aqueous slurry of MoO3. The thickness of the shell was regulated by the amount of MoO3. CoCO3 was adsorbed onto MoO3/ZrO2 from its aqueous slurry. The ZrO2-supported catalysts were compared to their TiO2-supported and industrial reference Al2O3-supported counterparts in a model reaction of benzothiophene hydrodesulfurization.

Selective Oxidation of Ethane Over Mo–V–Al–O Oxide Catalysts: Insight to the Factors Affecting the Selectivity of Ethylene and Acetic Acid and Structure-activity Correlation Studies

Catalysts of general formula, MoVAlOx were prepared with the initial elemental composition of 1:0.34:0.167 (Mo:V:Al) at a pH value in the range of 1–4. The elemental analysis showed that the final composition of the catalysts is pH dependant. The performance of the catalysts was tested for selective oxidation of ethane to give ethylene and acetic acid. While all of them were active for ethane oxidation with a moderate conversion, the catalyst prepared at pH 2 showed a highest activity with 23% ethane conversion and a combined selectivity of 80.6% to ethylene and acetic acid. The catalyst prepared at pH 4 was least selective to ethylene and acetic acid. Various techniques like powder XRD, SEM, Raman, UV–Vis and EPR were used to characterize the catalysts and to identify the active phases responsible for the selective oxidation of ethane. The powder XRD data showed that the catalysts prepared at pH 1 and 2 contain mainly of MoO3 and MoV2O8 along with traces of Mo4O11. The amount of MoO3 was slightly higher in the catalyst prepared at pH 1. However, the catalyst prepared at pH 3 contains mainly of MoV2O8 with no trace of MoO3. The catalyst prepared at pH 4 showed V2O5 as the major phase along with MoVAlO4 phase. The Raman data corroborated the XRD results. EPR and UV–Vis studies indicated the presence of traces of V4+ in pH 1 and 2 catalysts and significant amount of Mo5+ in all the catalysts. Thus, the high activity and selectivity to ethylene and acetic acid are attributed to the presence of MoV2O8 phase and other reduced species like Mo4O11 phase supported on MoO3. The presence of V and Mo ions in a partially reduced form seems to play a crucial role in the selective oxidation of ethane.

Mesoporous H-AlMCM-41 supported NiO-MoO 3 catalysts for hydrodenitrogenation of o-toluidine : I. Effect of MoO 3 loading

The mesoporous molecular sieve, H-AlMCM-41 (Si/Al = 100) was synthesized hydrothermally and used as support for the preparation of series of sequentially impregnated NiO-MoO 3 catalysts. Various amounts of MoO 3 (12, 18, 24 and 30 wt.%) along with of 7 wt.% of NiO were loaded in order to optimize the MoO 3 loading level for obtaining maximum HDN activity. These catalysts were well-characterized by physico-chemical techniques, such as X-ray diffraction (XRD), N 2 adsorption–desorption, SEM, FT-Raman spectroscopy, UV–vis DRS and FT-IR spectra of CO adsorption and tested for hydrodenitrogenation (HDN) of o-toluidine. The change in dispersion with MoO 3 loading was studied by FT-IR spectra of CO adsorbed samples. HDN activities of various NiO-MoO 3 catalysts were evaluated and the activities are accounted in terms of physico-chemical characteristics of the catalytic materials. Catalyst with 7 wt.% NiO-24 wt.% MoO 3 showed maximum HDN activity when compared to other catalysts and its enhanced activity due to the fine dispersion of MoO 3 as well as due to formation of an additional Ni–Mo–O phase from AlMCM-41, as revealed by FT-IR of CO adsorption, FT-Raman and XRD studies.

Surface and catalytic properties of MoO 3/Al 2O 3 system doped with Co 3O 4

Thermal solid–solid interactions in cobalt treated MoO 3/Al 2O 3 system were investigated using X-ray powder diffraction. The solids were prepared by wet impregnation method using Al(OH) 3, ammonium molybdate and cobalt nitrate solutions, drying at 100 °C then calcination at 300, 500, 750 and 1000 °C. The amount of MoO 3, was fixed at 16.67 mol% and those of cobalt oxide were varied between 2.04 and 14.29 mol% Co 3O 4. Surface and catalytic properties of various solid samples precalcined at 300 and 500 °C were studied using nitrogen adsorption at −196 °C, conversion of isopropanol at 200–500 °C and decomposition of H 2O 2 at 30–50 °C. The results obtained revealed that pure mixed solids precalcined at 300 °C consisted of AlOOH and MoO 3 phases. Cobalt oxide-doped samples calcined at the same temperature consisted also of AlOOH, MoO 3 and CoMoO 4 compounds. The rise in calcination temperature to 500 °C resulted in complete conversion of AlOOH into very poorly crystalline γ-Al 2O 3. The further increase in precalcination temperature to 750 °C led to the formation of Al 2(MoO 4) 3, κ-Al 2O 3 besides CoMoO 4 and un-reacted portion of Co 3O 4 in the samples rich in cobalt oxide. Pure MoO 3/Al 2O 3 preheated at 1000 °C composed of MoO 3–αAl 2O 3 solid solution (acquired grey colour). The doped samples consisted of the same solid solution together with CoMoO 4 and CoAl 2O 4 compounds. The increase in calcination temperature of pure and variously doped solids from 300 to 500 °C increased their specific surface areas and total pore volume which suffered a drastic decrease upon heating at 750 °C. Doping the investigated system with small amounts of cobalt oxide (2.04 and 4 mol%) followed by heating at 300 and 500 °C increased its catalytic activity in H 2O 2 decomposition. This increase, measured at 300 °C, attained 25.4- and 12.9-fold for the solids precalcined at 300 and 500 °C, respectively. The increase in the amount of dopant added above this limit decreased the catalytic activity which remained bigger than those of un-treated catalysts. On the other hand, the doping process decreased the catalytic activity of treated solids in isopropanol conversion especially the catalysts precalcined at 300 °C. This treatment modified the selectivities of treated solids towards dehydration and dehydrogenation of reacted alcohol. The activation energies of H 2O 2 decomposition were determined for pure and variously doped solids. The results obtained were discussed in light of induced changes in chemical composition and surface properties of the investigated system due to doping with cobalt oxide.

MoO2(acac)2 Catalysed Oxidative Deprotection of Oximes

Oximes undergo facile deprotection in acetone in the presence of a catalytic amount of MoO2(acac)2 and hydrogen peroxide.