The molten CaCl_(2)−CaMoO_(4) system was investigated,and the electrodeposition of protective Mo coatings on Ni plates was demonstrated.The results confirm the high solubility of solid CaMoO_(4) and the electrochemica...The molten CaCl_(2)−CaMoO_(4) system was investigated,and the electrodeposition of protective Mo coatings on Ni plates was demonstrated.The results confirm the high solubility of solid CaMoO_(4) and the electrochemical reactivity of MoO_(4)^(2-)ions in molten CaCl_(2).The eutectic temperature and composition of the system are identified as 1021 K and 4.74 wt.%CaMoO_(4),respectively.Under constant-current electrolysis conditions of−10 mA/cm^(2) at 1123 K,uniform and dense Mo coatings are obtained on Ni plates with up to 90.31%efficiency.Increasing the current density raises the overpotential,leading to refined grains and decreased roughness.The Mo-coated Ni plate exhibits a significant improvement in hardness and corrosion resistance.Microhardness increases from HV 46.00 to HV 215.10 after coating,and the corrosion rate in a 20 wt.%NaCl solution at room temperature decreases to 0.1%that of the bare plate.These findings enhance our understanding of the molten CaCl_(2)–CaMoO_(4) system and emphasize the potential of innovative Mo coating technologies.展开更多
This study investigates the compatibility and efficacy of combining ammonium molybdate(AM)with antagonistic bacteria Bacillus amyloliquefaciens B10W10 and Pseudomonas sp.B11W11 for brown rot control(Monilinia laxa).In...This study investigates the compatibility and efficacy of combining ammonium molybdate(AM)with antagonistic bacteria Bacillus amyloliquefaciens B10W10 and Pseudomonas sp.B11W11 for brown rot control(Monilinia laxa).In vitro experiments reveal variable mycelial growth inhibition rates compared to untreated controls,with B11W11+0.5%AM and B10W10+2%AM displaying the highest inhibition rates after 5 days.After 10 days,the 2%AM+B10W10 combination exhibits the highest inhibition rate.Microscopic observations show structural alterations in mycelium within inhibition zones,marked by vacuolization.The antagonistic bacteria,alone or with different ammonium molybdate concentrations,significantly impact M.laxa spore germination,with the B10W10 cell filtrate+2%ammonium molybdate combination achieving the most substantial inhibition.Conversely,the 0.5%ammonium molybdate treatment has the lowest inhibition rate while the combination of AM and bacteria is giving better results compared to the use of bacteria alone.Fruits treated with various antagonistic bacteria and ammonium molybdate combinations demonstrate a significant reduction in disease severity.The 0.5%AM+B10W10 combination exhibits the lowest severity.FT-IR spectra analysis identifies shifts in fungal biomass functional groups,with reduced lignin-related bands and increased phenols,lipids,polysaccharides,and carbohydrates.This highlights the structural modifications caused by the biological treatments.The study also evaluates the effects on fruit quality parameters.The 2%ammonium molybdate treatment yields the lowest weight loss.TSS levels are affected by salt concentration,while acid content remains consistent across treatments.All treatments influence fruit firmness compared to controls.These findings emphasize the potential of combining ammonium molybdate and antagonistic bacteria for effective brown rot control,highlighting their compatibility and effects on disease severity,fungal biomass,spore germination,and fruit quality.展开更多
Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-dope...Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.展开更多
The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)h...The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)has garnered increasing attention due to its cost-effectiveness,non-toxicity and earth abundance.To enhance the Li storage performance of Na_(2)MoO_(4)·2H_(2)O,a crystallographic orientation regulation strategy is proposed in this work.Initially,density functional theory calculations are carried out to demonstrate that the(020)crystal plane of Na_(2)MoO_(4)·2H_(2)O offers the lowest energy barrier for Li^(+)migration.Subsequently,the preferred crystallographic orientation of Na_(2)MoO_(4)·2H_(2)O crystal is tuned through a low-temperature recrystallization method.Furthermore,the microstructure and phase changes of Na_(2)MoO_(4)·2H_(2)O during the lithiation/de-lithiation process are studied using in situ and ex situ XRD tests,ex situ XPS and cyclic voltammetry to unravel its Li^(+)storage mechanism.Upon application as LIBs anode,the Na_(2)MoO_(4)·2H_(2)O single-crystal particles with a preferred(020)surface exhibit superior reversible capacity,high-capacity retention and high cycling stability.The enhanced Li storage performance should be attributed to the regulated crystallographic orientation and small changes in the crystal microstructure during the charge/discharge process,which facilitates Li^(+)migration and bolsters structural stability.Notably,this study introduces a novel concept and a simple synthesis method for the advancement of electrodes in rechargeable batteries.展开更多
Traditional resistive semiconductor gas sensors suffer from high operating temperatures and poor selectivity.Thus,to address these issues,a highly selective nitrogen dioxide(NO_(2))sensor based on lead sulfide(PbS)qua...Traditional resistive semiconductor gas sensors suffer from high operating temperatures and poor selectivity.Thus,to address these issues,a highly selective nitrogen dioxide(NO_(2))sensor based on lead sulfide(PbS)quantum dots(QDs)–lead molybdate(PbMoO_(4))–molybdenum disulfide(MoS_(2))ternary nanocomposites operating at room temperature was fabricated herein.The ternary nanocomposites were synthesized using an in situ method,yielding Pb S QDs with an average size of~10 nm and PbMoO_(4)nanoparticles in the 10-to 20-nm range,uniformly distributed on ultrathin MoS_(2)nanosheets with an average thickness of~7 nm.The optimized sensor demonstrated a significant improvement in response to 1 ppm NO_(2)at 25℃,achieving a response of 44.5%,which was approximately five times higher than that of the pure MoS_(2)-based sensor(8.5%).The sensor also achieved relatively short response/recovery times and full recovery properties.Notably,the optimal sensor displayed extraordinary selectivity toward NO_(2),showing negligible responses to different interfering gases.Density functional theory(DFT)calculations were conducted to elucidate the underlying sensing mechanism,which was attributed to the enhanced specific surface area,the receptor function of both PbS QDs and PbMoO_(4)nanoparticles,and the transducer function of MoS_(2) nanosheets.展开更多
The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media...The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.展开更多
Currently,endeavors to scale up the production of amorphous catalysts are still impeded by intricate synthesis conditions.Here,we have prepared a series of metal-based molybdate via one-step coprecipitation method.Aft...Currently,endeavors to scale up the production of amorphous catalysts are still impeded by intricate synthesis conditions.Here,we have prepared a series of metal-based molybdate via one-step coprecipitation method.After ingredient optimization,amorphous Co_(2)CeFe_(2)-MoO_(4) was identified as exhibiting the highest intrinsic activity among its counterparts.Modulation of electron structure enables Co_(2)CeFe_(2)-MoO_(4) to balance the adsorption behavior towards reactive intermediates.Ultimately,the obtained Co_(2)CeFe_(2)-MoO_(4) molybdate demonstrated a captivating OER performance,showcasing a low overpotential of 230 mV at 10 mA cm^(-2).Moreover,the alkaline electrolyzer employing the Co_(2)CeFe_(2)-MoO_(4) anode exhibited a low cell voltage of 1.50 V for water splitting and underwent an acceptable attenuation of 4.99% after 165 h of continuous operation,demonstrating its favorable catalytic activity and durability.This work provides a facile and eco-friendly synthesis pathway for crafting cost-effective and durable earth-abundant OER electrocatalysts tailored for water splitting to produce clean hydrogen.展开更多
Novel silver/silver molybdate（Ag/Ag2MoO4） composites with surface plasmon resonance（SPR）-enhanced photocatalytic performance were successfully fabricated via a facile one-pot hydrothermal route with the presence o...Novel silver/silver molybdate（Ag/Ag2MoO4） composites with surface plasmon resonance（SPR）-enhanced photocatalytic performance were successfully fabricated via a facile one-pot hydrothermal route with the presence of sodium dodecyl sulfate（SDS） in this study.The as prepared silver/silver molybdate（Ag/Ag2MoO4） composites were systematically characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and ultraviolet-visible diffuse reflectance absorption spectroscopy（DRS） in order to investigate their crystal structure,morphology and optical property as well.The photocatalytic activities of the composites were subsequently evaluated by their ability to degrade rhodamine B（RhB） under visible-light irradiation.Varies of controlled experiments were then carefully operated to gain a deep insight into the assembling of Ag/Ag2MoO4composites.It was found that preparation conditions such as pH,reaction time,and the amount of surfactant played important roles in the formation of composites with octahedral microstructures.And the composite obtained at 160 ℃ using 0.5 g of sodium dodecyl sulfate exhibited the highest photocatalytic performance under visible-light irradiation.Capture experiments were also conducted to clarify the function of different active species generated on the surface of Ag/Ag2MoO4during the photocatalytic process,in which both holes and ·OH radicals were found to play crucial role in photocatalytic removal of RhB under visible light irradiation.A possible photocatalytic mechanism of Ag/Ag2MoO4 was finally proposed on the basis of all the results to explain the higher photocatalytic activity of the octahedral Ag/Ag2MoO4 composites.It was inferred that the photoinduced ＂hot＂ electrons can quickly transfer from the Ag NPs to the conduction band of Ag2MoO4 and react with oxygen and H2O to generate a large quality of active radicals such as ·OH and ·O2^- because of the SPR effects.Besides,this SPR effects of Ag nanoparticles deposited on the surface of Ag2MoO4 can not only dramatically amplify its light absorption,especially in the visible region,but also promote the separation of photoexcited electron-hole pairs and effectively decrease electron-hole recombination.展开更多
The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the ...The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate.The ammonium molybdate was then calcined to produce mo-lybdic oxide.At the fusion stage,the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated.The results show that during the fusion,sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product.By melting at 850℃with 5wt%excess carbonate,the maximum solubility of the products is obtained.The molybdenum is recovered from the solutions as ammonium molybdate.展开更多
The removal of tungsten(W)and vanadium(V)from molybdate solutions was studied using the poly hydroxyl chelating resin D403in batch and column experiments.The batch experiments indicated that tungsten and vanadium coul...The removal of tungsten(W)and vanadium(V)from molybdate solutions was studied using the poly hydroxyl chelating resin D403in batch and column experiments.The batch experiments indicated that tungsten and vanadium could be preferentially adsorbed by the D403resin for4h in molybdate solution at a pH of approximately9.25.Separation factors,αVMo andαWMo,wereabove45and18,respectively,when the molar ratios of Mo/V and Mo/W in the solution exceeded40.Elution tests illustrated that vanadium and tungsten could be easily eluted from the resin with1mol/L sodium hydroxide solution in only1h.To further explore the sorption mechanism of the resin,the experimental equilibrium isotherm data of the three metals fitted well with the Freundlich model.The column experiments confirmed the adaptability of the D403resin in the production of sodium molybdate with a removal rate of tungsten surpassing90%and that of vanadium of99.4%.展开更多
We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle siz...We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.展开更多
This article investigated molybdenum recovery from oxygen pressure water leaching residue of Ni-Mo ore using alkaline leaching, followed by chemical treatment of leach liquor. Parameters affecting Mo leaching rate, su...This article investigated molybdenum recovery from oxygen pressure water leaching residue of Ni-Mo ore using alkaline leaching, followed by chemical treatment of leach liquor. Parameters affecting Mo leaching rate, such as sodium hydroxide concentration, reaction time, a liquid- to-solid ratio, and temperature for the preliminary alkaline leaching were experimentally determined. The results showed that more than 88 % of molybdenum was leached under the optimum conditions （2.5 ml.g-1 NaOH, 80 ℃, a liquid to solid ratio 3 ml.g-1, and reaction time 3 h）. After the purification of leach liquor, a CaMoO4 product of 99.2 % purity could be obtained by CaCla precipitation method. The whole Mo recovery reached about 82.7 %.展开更多
A series of Sm3＋ doped Y2MoO6 were prepared through high temperature solid state reaction technique. Their phase structures, morphologies and luminescence properties were investigated by X-ray diffraction （XRD）, sc...A series of Sm3＋ doped Y2MoO6 were prepared through high temperature solid state reaction technique. Their phase structures, morphologies and luminescence properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and photoluminescence spectrometry. The most intense absorption of Y2MoO6 host occurred at 367 nm. Energy transfer from host lattice to Sm3＋ ions could be observed, and the schematic diagram of energy transfer was constructed, The critical energy transfer dis- tance and energy transfer mechanism between Sm3＋ ions were discussed in detail. Considering the high color purity and appropriate emission intensity, Sm3＋ doped Y2MoO6 could be a promising phosphor under near ultraviolet light excitation.展开更多
Trivalent samarium ion (Sm^(3+)) activated calcium molybdate (CaMoO_4) phosphor was prepared by solid-state reaction in air. The XRD pattern of the powder CaMoO_4∶Sm shows that the CaMoO_4∶Sm single phase is develop...Trivalent samarium ion (Sm^(3+)) activated calcium molybdate (CaMoO_4) phosphor was prepared by solid-state reaction in air. The XRD pattern of the powder CaMoO_4∶Sm shows that the CaMoO_4∶Sm single phase is developed fully through our preparation procedure. The excitation spectrum of CaMoO_4∶Sm is composed of a broad absorption of host and some sharp lines of the f-f transition absorption of Sm^(3+). Illustrated in photoluminescence spectrum, CaMoO_4 doped with Sm^(3+) displays orange red emission that is ascribed to the inner 4f^5 electron transitions ~6H_(7/2)(orange)and ~6H_(9/2)(red)of Sm^(3+). Different from the sites of Sm^(3+) in CdWO_4, the Sm^(3+) ions substitute for the Ca^(2+) and form only one type emission center in the CaMoO_4 crystal lattice.展开更多
In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. We investigated the influences of two inorganic corrosion inhibitors(ammoniu...In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. We investigated the influences of two inorganic corrosion inhibitors(ammonium dihydrogen phosphate and sodium molybdate) on the corrosion resistance of anodic oxidation films on 2024 aluminum alloy, and studied the synergistic effect of two corrosion inhibitors. The corrosion resistance of anodic oxidation film in 3.5 wt% NaCl solution was evaluated by electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization curves. Results show that, after adding the single ammonium dihydrogen phosphate or sodium molybdate of 0.01 M to oxalic acid electrolyte, inhibition efficiencies of the anodized samples are 10% and 47%, respectively. However, in the presence of two inhibitors with the same concentration of 0.01 M, inhibition efficiency can be as high as 92%. Therefore, we observed the significantly synergistic corrosion inhibition effect of molybdate and phosphate ions for anodic oxidation film formed on 2024 aluminum alloy.展开更多
A novel transition metal ion bridging bis（diphosphopentamolybdates） has been synthesized and characterized by elemental analysis,IR spectrum,UV spectrum and single-crystal X-ray diffraction.The single-crystal struct...A novel transition metal ion bridging bis（diphosphopentamolybdates） has been synthesized and characterized by elemental analysis,IR spectrum,UV spectrum and single-crystal X-ray diffraction.The single-crystal structure analysis shows that the compound consists of seven charge-compensating 2,2＇-biimidazole cations （BIIM=2,2＇-biimidazole） and one dumbbell-like [Mn（H2O）4（P2Mo5O23）2]10-heteropolyanion which is constructed by two [P2Mo5O23]6-clusters bridged through one [Mn（H2O）4]2＋ cation.展开更多
Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of ...Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of phosphoric acid and hydrochloric acid was investigated.For further understanding of the leaching mechanism,the effects of five key factors were studied to describe the leaching kinetics.The results indicated that the dissolution rate of CaMoO4 was independent of the stirring speed.Mo extraction significantly increased with increasing HCl concentration and temperature,but decreased with increasing particle size.A shrinking core model with surface chemical reaction was found to withstand the dissolution of CaMoO4.The apparent activation energy was calculated to be 70.879 kJ/mol,and a semi-empirical equation was derived for the rate of reaction.展开更多
A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diff...A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.展开更多
In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the dop...In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu^3＋ concentration on the luminescent properties of Eu^3＋ doped SrMoO4 was investigated and the 25% （mole fraction） was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.展开更多
The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na2 Mo O4 and Na2WO4 solutions.The sorption isotherm results show that the...The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na2 Mo O4 and Na2WO4 solutions.The sorption isotherm results show that the adsorption process of W obeys the Freundlich model very well whereas the exchange process with Mo approximately follows the Henry model.The kinetic experiments show that the intraparticle diffusion process was the rate-determining step for W sorption on the resin,and the corresponding activation energy is calculated to be 21.976 k J/mol.展开更多
基金supported by Research Center for Industries of the Future(No.WU2022C034)at Westlake University,China。
文摘The molten CaCl_(2)−CaMoO_(4) system was investigated,and the electrodeposition of protective Mo coatings on Ni plates was demonstrated.The results confirm the high solubility of solid CaMoO_(4) and the electrochemical reactivity of MoO_(4)^(2-)ions in molten CaCl_(2).The eutectic temperature and composition of the system are identified as 1021 K and 4.74 wt.%CaMoO_(4),respectively.Under constant-current electrolysis conditions of−10 mA/cm^(2) at 1123 K,uniform and dense Mo coatings are obtained on Ni plates with up to 90.31%efficiency.Increasing the current density raises the overpotential,leading to refined grains and decreased roughness.The Mo-coated Ni plate exhibits a significant improvement in hardness and corrosion resistance.Microhardness increases from HV 46.00 to HV 215.10 after coating,and the corrosion rate in a 20 wt.%NaCl solution at room temperature decreases to 0.1%that of the bare plate.These findings enhance our understanding of the molten CaCl_(2)–CaMoO_(4) system and emphasize the potential of innovative Mo coating technologies.
基金supported by the Phytopathology Unit of the Department of Plant Protection(ENA-Meknes,Morocco).
文摘This study investigates the compatibility and efficacy of combining ammonium molybdate(AM)with antagonistic bacteria Bacillus amyloliquefaciens B10W10 and Pseudomonas sp.B11W11 for brown rot control(Monilinia laxa).In vitro experiments reveal variable mycelial growth inhibition rates compared to untreated controls,with B11W11+0.5%AM and B10W10+2%AM displaying the highest inhibition rates after 5 days.After 10 days,the 2%AM+B10W10 combination exhibits the highest inhibition rate.Microscopic observations show structural alterations in mycelium within inhibition zones,marked by vacuolization.The antagonistic bacteria,alone or with different ammonium molybdate concentrations,significantly impact M.laxa spore germination,with the B10W10 cell filtrate+2%ammonium molybdate combination achieving the most substantial inhibition.Conversely,the 0.5%ammonium molybdate treatment has the lowest inhibition rate while the combination of AM and bacteria is giving better results compared to the use of bacteria alone.Fruits treated with various antagonistic bacteria and ammonium molybdate combinations demonstrate a significant reduction in disease severity.The 0.5%AM+B10W10 combination exhibits the lowest severity.FT-IR spectra analysis identifies shifts in fungal biomass functional groups,with reduced lignin-related bands and increased phenols,lipids,polysaccharides,and carbohydrates.This highlights the structural modifications caused by the biological treatments.The study also evaluates the effects on fruit quality parameters.The 2%ammonium molybdate treatment yields the lowest weight loss.TSS levels are affected by salt concentration,while acid content remains consistent across treatments.All treatments influence fruit firmness compared to controls.These findings emphasize the potential of combining ammonium molybdate and antagonistic bacteria for effective brown rot control,highlighting their compatibility and effects on disease severity,fungal biomass,spore germination,and fruit quality.
文摘Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.
基金supported by the Natural Science Foundation of Guizhou Province(No.ZK 2022-044)the Platform of Science and Technology and Talent Team Plan of Guizhou Province(No.GCC[2023]007)+1 种基金the National Science Foundation of China(Nos.52101010 and 11964006)the Fund of Natural Science Special(Special Post)Research Foundation of Guizhou University(No.2021-018).
文摘The design and development of high-performance anodes pose significant challenges in the construction of next-generation rechargeable lithium-ion batteries(LIBs).Sodium molybdate dihydrate(Na_(2)MoO_(4)·2H_(2)O)has garnered increasing attention due to its cost-effectiveness,non-toxicity and earth abundance.To enhance the Li storage performance of Na_(2)MoO_(4)·2H_(2)O,a crystallographic orientation regulation strategy is proposed in this work.Initially,density functional theory calculations are carried out to demonstrate that the(020)crystal plane of Na_(2)MoO_(4)·2H_(2)O offers the lowest energy barrier for Li^(+)migration.Subsequently,the preferred crystallographic orientation of Na_(2)MoO_(4)·2H_(2)O crystal is tuned through a low-temperature recrystallization method.Furthermore,the microstructure and phase changes of Na_(2)MoO_(4)·2H_(2)O during the lithiation/de-lithiation process are studied using in situ and ex situ XRD tests,ex situ XPS and cyclic voltammetry to unravel its Li^(+)storage mechanism.Upon application as LIBs anode,the Na_(2)MoO_(4)·2H_(2)O single-crystal particles with a preferred(020)surface exhibit superior reversible capacity,high-capacity retention and high cycling stability.The enhanced Li storage performance should be attributed to the regulated crystallographic orientation and small changes in the crystal microstructure during the charge/discharge process,which facilitates Li^(+)migration and bolsters structural stability.Notably,this study introduces a novel concept and a simple synthesis method for the advancement of electrodes in rechargeable batteries.
基金supported by the National Natural Science Foundation of China(No.52274255)Fundamental Research Funds for the Central Universities,China(Nos.N2401003,N2301003,N2201008,N2201004,and N2301025)+3 种基金Liaoning Revitalization Talents Program,China(No.XLYC2202028)Postdoctoral Foundation of Northeastern University,ChinaYoung Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)China Postdoctoral Science Foundation(No.2022M720025)。
文摘Traditional resistive semiconductor gas sensors suffer from high operating temperatures and poor selectivity.Thus,to address these issues,a highly selective nitrogen dioxide(NO_(2))sensor based on lead sulfide(PbS)quantum dots(QDs)–lead molybdate(PbMoO_(4))–molybdenum disulfide(MoS_(2))ternary nanocomposites operating at room temperature was fabricated herein.The ternary nanocomposites were synthesized using an in situ method,yielding Pb S QDs with an average size of~10 nm and PbMoO_(4)nanoparticles in the 10-to 20-nm range,uniformly distributed on ultrathin MoS_(2)nanosheets with an average thickness of~7 nm.The optimized sensor demonstrated a significant improvement in response to 1 ppm NO_(2)at 25℃,achieving a response of 44.5%,which was approximately five times higher than that of the pure MoS_(2)-based sensor(8.5%).The sensor also achieved relatively short response/recovery times and full recovery properties.Notably,the optimal sensor displayed extraordinary selectivity toward NO_(2),showing negligible responses to different interfering gases.Density functional theory(DFT)calculations were conducted to elucidate the underlying sensing mechanism,which was attributed to the enhanced specific surface area,the receptor function of both PbS QDs and PbMoO_(4)nanoparticles,and the transducer function of MoS_(2) nanosheets.
基金Project supported by Jilin Provincial Department of Education(JJKH20230821KJ,JJKH20230822KJ,JJKH20230823KJ,JJKH20240930KJ,20240101107JC)。
文摘The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.
基金supported by the National Natural Science Foundation of China (No. 21872153)。
文摘Currently,endeavors to scale up the production of amorphous catalysts are still impeded by intricate synthesis conditions.Here,we have prepared a series of metal-based molybdate via one-step coprecipitation method.After ingredient optimization,amorphous Co_(2)CeFe_(2)-MoO_(4) was identified as exhibiting the highest intrinsic activity among its counterparts.Modulation of electron structure enables Co_(2)CeFe_(2)-MoO_(4) to balance the adsorption behavior towards reactive intermediates.Ultimately,the obtained Co_(2)CeFe_(2)-MoO_(4) molybdate demonstrated a captivating OER performance,showcasing a low overpotential of 230 mV at 10 mA cm^(-2).Moreover,the alkaline electrolyzer employing the Co_(2)CeFe_(2)-MoO_(4) anode exhibited a low cell voltage of 1.50 V for water splitting and underwent an acceptable attenuation of 4.99% after 165 h of continuous operation,demonstrating its favorable catalytic activity and durability.This work provides a facile and eco-friendly synthesis pathway for crafting cost-effective and durable earth-abundant OER electrocatalysts tailored for water splitting to produce clean hydrogen.
基金supported by Fundamental Research Funds for the Central Universities (2662014BQ061, 2015PY120, 2015PY047, 2016PY088)the National Natural Science Foundation of China (51572101, 21502059, 21607047)~~
文摘Novel silver/silver molybdate（Ag/Ag2MoO4） composites with surface plasmon resonance（SPR）-enhanced photocatalytic performance were successfully fabricated via a facile one-pot hydrothermal route with the presence of sodium dodecyl sulfate（SDS） in this study.The as prepared silver/silver molybdate（Ag/Ag2MoO4） composites were systematically characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and ultraviolet-visible diffuse reflectance absorption spectroscopy（DRS） in order to investigate their crystal structure,morphology and optical property as well.The photocatalytic activities of the composites were subsequently evaluated by their ability to degrade rhodamine B（RhB） under visible-light irradiation.Varies of controlled experiments were then carefully operated to gain a deep insight into the assembling of Ag/Ag2MoO4composites.It was found that preparation conditions such as pH,reaction time,and the amount of surfactant played important roles in the formation of composites with octahedral microstructures.And the composite obtained at 160 ℃ using 0.5 g of sodium dodecyl sulfate exhibited the highest photocatalytic performance under visible-light irradiation.Capture experiments were also conducted to clarify the function of different active species generated on the surface of Ag/Ag2MoO4during the photocatalytic process,in which both holes and ·OH radicals were found to play crucial role in photocatalytic removal of RhB under visible light irradiation.A possible photocatalytic mechanism of Ag/Ag2MoO4 was finally proposed on the basis of all the results to explain the higher photocatalytic activity of the octahedral Ag/Ag2MoO4 composites.It was inferred that the photoinduced ＂hot＂ electrons can quickly transfer from the Ag NPs to the conduction band of Ag2MoO4 and react with oxygen and H2O to generate a large quality of active radicals such as ·OH and ·O2^- because of the SPR effects.Besides,this SPR effects of Ag nanoparticles deposited on the surface of Ag2MoO4 can not only dramatically amplify its light absorption,especially in the visible region,but also promote the separation of photoexcited electron-hole pairs and effectively decrease electron-hole recombination.
文摘The production of MoO3 from Sarcheshmeh molybdenite concentrate via a pyro-hydrometallurgical process was studied.The molybdenite concentrate and sodium carbonate were premixed and fused under air atmosphere.Then the fused products were leached in water and the dissolved molybdenum was recovered as ammonium molybdate.The ammonium molybdate was then calcined to produce mo-lybdic oxide.At the fusion stage,the effect of the mass ratio of carbonate to sulfide on the reaction products and the solubility of the products was investigated.The results show that during the fusion,sodium molybdate and sodium sulfate are the final reaction products and sodium sulfide is detected as an intermediate reaction product.By melting at 850℃with 5wt%excess carbonate,the maximum solubility of the products is obtained.The molybdenum is recovered from the solutions as ammonium molybdate.
基金Project(2014CB643405)supported by the National Basic Research Program of China
文摘The removal of tungsten(W)and vanadium(V)from molybdate solutions was studied using the poly hydroxyl chelating resin D403in batch and column experiments.The batch experiments indicated that tungsten and vanadium could be preferentially adsorbed by the D403resin for4h in molybdate solution at a pH of approximately9.25.Separation factors,αVMo andαWMo,wereabove45and18,respectively,when the molar ratios of Mo/V and Mo/W in the solution exceeded40.Elution tests illustrated that vanadium and tungsten could be easily eluted from the resin with1mol/L sodium hydroxide solution in only1h.To further explore the sorption mechanism of the resin,the experimental equilibrium isotherm data of the three metals fitted well with the Freundlich model.The column experiments confirmed the adaptability of the D403resin in the production of sodium molybdate with a removal rate of tungsten surpassing90%and that of vanadium of99.4%.
基金Project supported by the National Natural Science Foundation of China(51002041)
文摘We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.
基金supported by the National High Technology Research and Development Program of China(No.2009AA06Z106)Yunnan Provincial Science and Technology Department of China(No.2011GA004)
文摘This article investigated molybdenum recovery from oxygen pressure water leaching residue of Ni-Mo ore using alkaline leaching, followed by chemical treatment of leach liquor. Parameters affecting Mo leaching rate, such as sodium hydroxide concentration, reaction time, a liquid- to-solid ratio, and temperature for the preliminary alkaline leaching were experimentally determined. The results showed that more than 88 % of molybdenum was leached under the optimum conditions （2.5 ml.g-1 NaOH, 80 ℃, a liquid to solid ratio 3 ml.g-1, and reaction time 3 h）. After the purification of leach liquor, a CaMoO4 product of 99.2 % purity could be obtained by CaCla precipitation method. The whole Mo recovery reached about 82.7 %.
基金Project supported by the Educational Commission of Jiangxi Province of China(GJJ150632)Natural Science Foundation of Jiangxi Province(20161BAB216124)
文摘A series of Sm3＋ doped Y2MoO6 were prepared through high temperature solid state reaction technique. Their phase structures, morphologies and luminescence properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and photoluminescence spectrometry. The most intense absorption of Y2MoO6 host occurred at 367 nm. Energy transfer from host lattice to Sm3＋ ions could be observed, and the schematic diagram of energy transfer was constructed, The critical energy transfer dis- tance and energy transfer mechanism between Sm3＋ ions were discussed in detail. Considering the high color purity and appropriate emission intensity, Sm3＋ doped Y2MoO6 could be a promising phosphor under near ultraviolet light excitation.
文摘Trivalent samarium ion (Sm^(3+)) activated calcium molybdate (CaMoO_4) phosphor was prepared by solid-state reaction in air. The XRD pattern of the powder CaMoO_4∶Sm shows that the CaMoO_4∶Sm single phase is developed fully through our preparation procedure. The excitation spectrum of CaMoO_4∶Sm is composed of a broad absorption of host and some sharp lines of the f-f transition absorption of Sm^(3+). Illustrated in photoluminescence spectrum, CaMoO_4 doped with Sm^(3+) displays orange red emission that is ascribed to the inner 4f^5 electron transitions ~6H_(7/2)(orange)and ~6H_(9/2)(red)of Sm^(3+). Different from the sites of Sm^(3+) in CdWO_4, the Sm^(3+) ions substitute for the Ca^(2+) and form only one type emission center in the CaMoO_4 crystal lattice.
基金Funded by the General Program of Natural Science Foundation of Jiangsu Province of China(No.BK20171440)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(NY218039)
文摘In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. We investigated the influences of two inorganic corrosion inhibitors(ammonium dihydrogen phosphate and sodium molybdate) on the corrosion resistance of anodic oxidation films on 2024 aluminum alloy, and studied the synergistic effect of two corrosion inhibitors. The corrosion resistance of anodic oxidation film in 3.5 wt% NaCl solution was evaluated by electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization curves. Results show that, after adding the single ammonium dihydrogen phosphate or sodium molybdate of 0.01 M to oxalic acid electrolyte, inhibition efficiencies of the anodized samples are 10% and 47%, respectively. However, in the presence of two inhibitors with the same concentration of 0.01 M, inhibition efficiency can be as high as 92%. Therefore, we observed the significantly synergistic corrosion inhibition effect of molybdate and phosphate ions for anodic oxidation film formed on 2024 aluminum alloy.
基金Supported by the Natural Science Foundation of Henan Province (No. 0611011900)
文摘A novel transition metal ion bridging bis（diphosphopentamolybdates） has been synthesized and characterized by elemental analysis,IR spectrum,UV spectrum and single-crystal X-ray diffraction.The single-crystal structure analysis shows that the compound consists of seven charge-compensating 2,2＇-biimidazole cations （BIIM=2,2＇-biimidazole） and one dumbbell-like [Mn（H2O）4（P2Mo5O23）2]10-heteropolyanion which is constructed by two [P2Mo5O23]6-clusters bridged through one [Mn（H2O）4]2＋ cation.
基金Project(2017M610766)supported by China Postdoctoral Science FoundationProject(FRF-BD-17-010A)supported by the Fundamental Research Funds for the Central Universities,China
文摘Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of phosphoric acid and hydrochloric acid was investigated.For further understanding of the leaching mechanism,the effects of five key factors were studied to describe the leaching kinetics.The results indicated that the dissolution rate of CaMoO4 was independent of the stirring speed.Mo extraction significantly increased with increasing HCl concentration and temperature,but decreased with increasing particle size.A shrinking core model with surface chemical reaction was found to withstand the dissolution of CaMoO4.The apparent activation energy was calculated to be 70.879 kJ/mol,and a semi-empirical equation was derived for the rate of reaction.
基金Project(51374185) supported by the National Natural Science Foundation of China
文摘A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.
基金Project supported by the Hebei Developing Foundation of Science &Technology (51215103b)
文摘In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu^3＋ concentration on the luminescent properties of Eu^3＋ doped SrMoO4 was investigated and the 25% （mole fraction） was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.
基金Project (2014CB643405) supported by National Research Development Program of China
文摘The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na2 Mo O4 and Na2WO4 solutions.The sorption isotherm results show that the adsorption process of W obeys the Freundlich model very well whereas the exchange process with Mo approximately follows the Henry model.The kinetic experiments show that the intraparticle diffusion process was the rate-determining step for W sorption on the resin,and the corresponding activation energy is calculated to be 21.976 k J/mol.
