Element superconductors with the single atoms provide clean and fundamental platforms for studying superconductivity.Although elements with d electrons are usually not favored by conventional BCS,the record supercondu...Element superconductors with the single atoms provide clean and fundamental platforms for studying superconductivity.Although elements with d electrons are usually not favored by conventional BCS,the record superconducting critical temperature(T_(c))in element scandium(S_(c))has further ignited the intensive attention on transition metals.The element molybdenum(M_o)with a half-full d-orbital is studied in our work,which fills the gap in the study of Mo under high pressure and investigates the pressure dependence of superconductivity.In this work,we exhibit a robust superconductivity of Mo in the pressure range of 5 GPa to 160 GPa via high-pressure electrical transport measurements,the T_(c) varies at a rate of0.013 K/GPa to 8.56 K at 160 GPa.Moreover,the superconductivity is evidenced by the T_(c) shifting to lower temperature under applied magnetic fields,and the upper critical magnetic fields are extrapolated by the WHH equation and GL equation;the results indicate that the maximum upper critical magnetic field is estimated to be 8.24 T at 137 GPa.We further investigate the superconducting mechanism of Mo,the theoretical calculations indicate that the superconductivity can be attributed to the strong coupling between the electrons from the partially filled d band and the phonons from the frequency zone of 200-400 cm^(-1).展开更多
The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient ...The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.展开更多
In a single sample plot,the total amount of heavy metals in the soil could not necessarily reflect the contents of their effective states.This must be considered when attempting to determine the degree of soil heavy-m...In a single sample plot,the total amount of heavy metals in the soil could not necessarily reflect the contents of their effective states.This must be considered when attempting to determine the degree of soil heavy-metal pollution in an area.In the present study,the soil around the molybdenum mining area in Huludao,China,was surveyed and sampled to evaluate soil heavy-metal pollution using the Nemerow multifactor pollution index method.The Tessier continuous extraction method was used to analyze the distribution of heavy-metal forms'and their content changes in the soil of this area.Thus,the bioactivity of heavy metals in the soil,the absorption of heavy metals by plants,and the distribution of heavy metals in plants were explored to provide data supporting the use of phytoremediation technology to treat the heavy-metal pollution in the molybdenum mining area and develop ecological restoration strategies for the area's wastelands.The pollution index results indicate that heavy-metal pollution in the soil around the tailings pond is severe,mainly due to Pb and Zn heavy metals.Heavy-metal pollution in the surrounding land is mainly due to Cd and Zn.Content analysis of the heavy-metal forms/states in soils shows that exchangeable forms,which are most effective and toxic to plants,of the following metals are highest in the following areas:Cd,Cu,and Zn in the mountains around the stope;Zn,Mo,and Cu in the cultivated land around the dump;and Cd,Zn,and Mo in the cultivated land around the tailings pond.The pollution index analysis provides a basic overview of soil heavy-metal pollution across the entire mining area.However,content analysis of heavy-metal forms/states better reflects the relationship between the availability of heavy metals in the soil and the effectiveness of plants.Thus,the latter analysis can help ensure that phytoremediation strategies are adequately targeted,science-based,and effective.展开更多
Selective synthesis of ethanol from syngas under the Co-based catalysts is still challenging due to the hard of regulating the active site Co^(0) and Co^(2+)ratio.In this work,a series of CaTi_(0.9-x)Co_(x)Mo_(0.1)O_(...Selective synthesis of ethanol from syngas under the Co-based catalysts is still challenging due to the hard of regulating the active site Co^(0) and Co^(2+)ratio.In this work,a series of CaTi_(0.9-x)Co_(x)Mo_(0.1)O_(3)(x=0,0.1-0.4)and CaTi_(0.7)Co_(0.3)O_(3) catalysts were prepared by using citric acid complexation method to promote the synthesis of ethanol.It was found that Mo species in the perovskite lattice can regulate the Co^(0) and Co^(2+)ratio through the domain-limiting effect of perovskite and the degree of Co reduction could be adjusted by changing the Co/Mo molar ratio.Among these investigated catalysts,the total selectivity of alcohols over the catalyst with the optimal Co/Mo ratio CaTi_(0.6)Co_(0.3)Mo_(0.1)O_(3) reached 39.1%,with ethanol accounting for 74.7%,which was ascribed to the moderate and tightly bound ratio of dissociative to non-dissociative adsorption sites on the surface and the balance of CH_(x)-CH_(y) coupling and C^(O) insertion.展开更多
Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evoluti...Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction(HER)occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed.Therefore,efficient platinum group metals(PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded.In this scenario,molybdenum disulfide(MoS_(2))owing to efficacious structural attributes and optimum hydrogen-binding free energy(ΔG_(H*))is emerging as a reliable alternative to PGMs.However,the performance of MoS_(2)-based electrocatalysts is still far away from the benchmark performance.The HER activity of MoS_(2)can be improved by engineering the structural parameters i.e.,doping,defects inducement,modulating the electronic structure,stabilizing the 1 T phase,creating nanocomposites,and altering the morphologies using appropriate fabrication pathways.Here,we have comprehensively reviewed the majority of the scientific endeavors published in recent years to uplift the HER activity of MoS_(2)-based electrocatalysts using different methods.Advancements in the major fabrication strategies including hydrothermal synthesis methods,chemical vapor deposition,exfoliation techniques,plasma treatments,chemical methodologies,etc.to tune the structural parameters and hence their ultimate influence on the electrocatalytic activity in acidic and/or alkaline media have been thoroughly discussed.This study can provide encyclopedic insights about the fabrication routes that have been pursued to improve the HER performance of MoS_(2)-based electrocatalysts.展开更多
Zero-dimensional environmentally friendly carbon quantum dots(CQDs)combined with two-di-mensional materials have a wide range of applications in optoelec-tronic devices.We combined steady-state and transient absorp-ti...Zero-dimensional environmentally friendly carbon quantum dots(CQDs)combined with two-di-mensional materials have a wide range of applications in optoelec-tronic devices.We combined steady-state and transient absorp-tion spectroscopies to study the energy transfer dynamics between CQDs and molybdenum disulfide(MoS_(2)).Transient absorption plots showed photoinduced absorption and stimulated emission features,which involved the intrinsic and defect states of CQDs.Adding MoS_(2)to CQDs solution,the lowest unoccupied molecular orbital of CQDs transferred energy to MoS_(2),which quenched the intrinsic emission at 390 nm.With addition of MoS_(2),CQD-MoS_(2)composites quenched defect emission at 490 nm and upward absorption,which originated from another energy transfer from the defect state.Two energy transfer paths between CQDs and MoS_(2)were efficiently manipulated by changing the concentration of MoS_(2),which laid a foundation for improving device performance.展开更多
Metal-ion capacitors could merit advantages from both batteries and capacitors,but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific cap...Metal-ion capacitors could merit advantages from both batteries and capacitors,but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific capacitance of capacitor type electrode for both high energy and power density.Herein,we use the Kirkendall effect for the first time to synthesize unique tubular hierarchical molybdenum dioxide with encapsulated nitrogen-doped carbon sheets while in situ realizing phosphorus-doping to create rich oxygen vacancies(P-MoO_(2-x)@NP-C)as a sodium-ion electrode.Experimental and theoretical analysis confirm that the P-doping introduced oxygen defects can partially convert the high-bond-energy Mo–O to low-bond-energy Mo–P,resulting in a low oxidation state of molybdenum for enhanced surface reactivity and rapid reaction kinetics.The as-prepared P-MoO_(2-x)@NP-C as an ion-battery electrode is further used to pair active N-doped carbon nanosheet(N-C-A)electrode for Na-ion hybrid capacitor,delivering excellent performance with an energy density of 140.3 Wh kg^(−1),a power density of 188.5 W kg^(−1)and long stable life in non-aqueous solution,which ranks the best among all reported MoO x-based hybrid capacitors.P-MoO_(2-x)@NP-C is also used to fabricate a zinc-ion hybrid capacitor,also accomplishing a remarkable energy density of 43.8 Wh kg^(−1),a power density of 93.9 W kg^(−1),and a long stable life@2A g^(−1)of 32000 cycles in aqueous solutions,solidly verifying its universal significance.This work not only demonstrates an innovative approach to synthesize high-performance metal ion hybrid capacitor materials but also reveals certain scientific insights into electron transfer enhancement mechanisms.展开更多
The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with tot...The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with total molybdenum reserves of 1.65 billion tons,an average molybdenum ore grade of 0.081%,and molybdenum resources of 1.09 million tons.The main ore body is housed in the granodiorite porphyry plutons and their surrounding inequigranular granodiorite plutons,with high-grade ores largely located in the ore-bearing granodiorite porphyries in the middle-upper part of the porphyry plutons.Specifically,it appears as an ore pipe with a large upper part and a small lower part,measuring about 1700 m in length and width,extending for about 500 m vertically,and covering an area of 2.3 km^(2).Mineralogically,the main ore body consists of molybdenite,chalcopyrite,and sphalerite horizontally from its center outward and exhibits molybdenite,azurite,and pyrite vertically from top to bottom.The primary ore minerals include pyrite and molybdenite,and the secondary ore minerals include sphalerite,chalcopyrite,tetrahedrite,and scheelite,with average grades of molybdenum,copper,sulfur,gallium,and rhenium being 0.081%,0.033%,1.67%,0.001%,and 0.0012%,respectively.The ore-forming fluids of the Daheishan deposit originated as the CO_(2)-H_(2)O-NaCl multiphase magmatic fluid system,rich in CO_(2)and bearing minor amounts of CH4,N2,and H2S,and later mixed with meteoric precipitation.In various mineralization stages,the ore-forming fluids had homogenization temperatures of>420℃‒400℃,360℃‒350℃,340℃‒230℃,220℃‒210℃,and 180℃‒160℃and salinities of>41.05%‒9.8%NaCleqv,38.16%‒4.48%NaCleqv,35.78%‒4.49%NaCleqv,7.43%NaCleqv,and 7.8%‒9.5%NaCleqv,respectively.The mineralization of the Daheishan deposit occurred at 186‒167 Ma.The granites closely related to the mineralization include granodiorites(granodiorite porphyries)and monzogranites(monzogranite porphyries),which were mineralized after magmatic evolution(189‒167 Ma).Moreover,these mineralization-related granites exhibit low initial strontium content and high initial neodymium content,indicating that these granites underwent crust-mantle mixing.The Daheishan deposit formed during the Early-Middle Jurassic,during which basaltic magma underplating induced the lower-crust melting,leading to the formation of magma chambers.After the fractional crystallization of magmas,ore-bearing fluids formed.As the temperature and pressure decreased,the ore-bearing fluids boiled drops while ascending,leading to massive unloading of metal elements.Consequently,brecciated and veinlet-disseminated ore bodies formed.展开更多
Currently the catalysis of hydrogen evolution reaction(HER)is mainly focused on the inherent electrocatalytic activity at relatively lower current densities while scarce at high current densities.Nevertheless,the latt...Currently the catalysis of hydrogen evolution reaction(HER)is mainly focused on the inherent electrocatalytic activity at relatively lower current densities while scarce at high current densities.Nevertheless,the latter is highly demanding in efficient mass-production of hydrogen.A SiO_(2) nanospheres template-synthesis is used to prepare mesoporous molybdenum carbide nanocrystals-embedded nitrogen-doped carbon foams(mp-Mo_(2)C/NC).The material shows much more excellent catalytic activity than the non-etched Mo_(2)C/NC toward hydrogen evolution reaction(HER)in acidic medium.More interestingly mp-Mo_(2)C/NC still has larger overpotential than Pt/C at lower current densities,but possess remarkably smaller overpotential than the latter at higher current densities for much better electrocatalytic performance.An approach is developed to investigate the electrode kinetics by Tafel plots,especially with eliminating the diffusion effect,indicating that Pt/C and mp-Mo_(2)C/NC display different reaction mechanisms.At low current densities the former presents reversible reaction,while the latter shows mixed electrochemical polarization/reversible electrode process.In the region of higher current densities,the former becomes totally gas-diffusion controlled with large overpotential,while the latter can still retain an electrode polarization process for much lower overpotential at the same current density.Result endorses that the meso-porously structured mp-Mo_(2)C/NC plays a critical role in avoiding gas diffusion control-resulting large overpotential at high current densities.This work holds great potential for an inexpensive catalyst better than Pt/C in practical applications of mass-production hydrogen at high current densities,while clearly shedding fundamental lights on designs of rational HER catalysts for the uses at high current densities.展开更多
The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in mate...The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in materials are related to the intrinsic Fermi energy levels in materials by the universal mass-energy equivalence equation given as dE/E=dm/m,where E is the energy and m is the mass of the free electron.The known parameters of electron effective mass of 0.48 m and the direct bandgap of 1.8 eV for monolayer MoS_(2) semiconductor are utilized to determine the properties of the MOS(metal-oxide-semiconductor)device,with the given previous research consequence that the threshold for electron heating in SiO_(2) is 2 MV/cm-eV.展开更多
A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear Mo...A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear MoDDCs.This control assists in the tailoring of specific tribological properties of the MoDDCs in both greases and lubricating oils.展开更多
The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted...The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.展开更多
Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the ...Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.展开更多
The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite...The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation.LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,one were formed at 181.7±7.4 Ma and the other at 133.6±3.3 Ma.The latter age is beli...展开更多
Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungs...Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungsten, La- Mo cathode has higher emission current density at lower temperature, but it has poor emission stability. In order to im- prove the emission stability, systematical Study on the emission mechanism of La-Mo cathode has been carried out. The life of La-Mo cathode has been improved and has achieved 1400 h, which exceeds the minimum life for practical uses (1000 h). As another alternative for thoriated tungsten cathode, Y-Mo cathode has shown better performance. The ther- mionic emission capability of Y-Mo cathode is between that of La-Mo cathode and Th-W cathode.展开更多
The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (III) produced by a Jones rcductor was investigated using a flow injection system. On the basis of this, a novel method for the determination o...The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (III) produced by a Jones rcductor was investigated using a flow injection system. On the basis of this, a novel method for the determination of trace amount of molybdenum has been established. The emission intensity was linear with molybdenum concentration in the range of 0.1-1000ng/mL; the detection limit was 0.02 ng/mL molybdenum, the relative standard deviation was less than 2% for the determination of 0.1 ng/mL molybdenum (n=11). The method has been applied successfully to the analysis of trace molybdenum in water and steel samples.展开更多
Hypoeutectic Fe-Cr-B-C hardfacing alloys with different molybdenum( Mo) contents( The design content was 0,2,3. 3 and 4. 5 wt. %,respectively) were deposited using the flux-cored wire by means of metal active gas arc ...Hypoeutectic Fe-Cr-B-C hardfacing alloys with different molybdenum( Mo) contents( The design content was 0,2,3. 3 and 4. 5 wt. %,respectively) were deposited using the flux-cored wire by means of metal active gas arc welding. The effects of Mo on the refinement of microstructures,eutectic microstructure changes and improvement of wear resistance were investigated. The main results were shown as follows: the added Mo could increase the volume fraction of eutectic microstructure and reduce the size of coarse primary austenite as well as the volume fraction. The carboboride of M_3( B,C) could be observed in hypoeutectic Fe-Cr-B-C hardfacing alloys at the Mo design content of ≤2. 0 wt. %,while that of M_(23)( B,C)_(6) was formed when 3. 3 wt. % Mo was added.Additionally,the wear resistance of alloys was increased with the increase in Mo content. Specifically,the highest wear resistance of alloys was achieved at 4. 5 wt. % Mo design content,which was 113. 7% higher than that in alloys without Mo.展开更多
An experimental setup has been designed and realized in order to optimize the characteristics of laser-induced breakdown spectroscopy system working in various pressure environments. An approach combined the normaliza...An experimental setup has been designed and realized in order to optimize the characteristics of laser-induced breakdown spectroscopy system working in various pressure environments. An approach combined the normalization methods with the partial least squares(PLS) method are developed for quantitative analysis of molybdenum(Mo) element in the multi-component alloy,which is the first wall material in the Experimental Advanced Superconducting Tokamak. In this study, the different spectral normalization methods(total spectral area normalization,background normalization, and reference line normalization) are investigated for reducing the uncertainty and improving the accuracy of spectral measurement. The results indicates that the approach of PLS based on inter-element interference is significantly better than the conventional PLS methods as well as the univariate linear methods in the various pressure for molybdenum element analysis.展开更多
The complex (Bu4N) 2 [Mo2O5 (mp)2] was synthesized by the reactionof (Bu4N)2[Mo8O26] with H2mp (H2mp=o-mercaptophenol) in methanol. The molecular formula is C44H80Mo2N2O7S2, M.=1005.10. The complex is crystallized in ...The complex (Bu4N) 2 [Mo2O5 (mp)2] was synthesized by the reactionof (Bu4N)2[Mo8O26] with H2mp (H2mp=o-mercaptophenol) in methanol. The molecular formula is C44H80Mo2N2O7S2, M.=1005.10. The complex is crystallized in monoclinic, space group P21/n with unit cell parameters, a = 17. 829 (2) A, b= 13. 759 (2 )A,c= 21. 974(2) A, g=105. 386(8)°, V= 5197. 4(1) , Dc= 1. 285 g/cm3, Z=4,λ(MoKa) =0. 71073 , μ=0. 607 mm-1,F(000) = 2120, final R=0.0348 and wR=0. 0741 for 4912 independent observed reflections (FM>4σ(Fo) ). Two MoO5S units inthe complex molecule exhibits the con facial distorted bioctahedral geometry and possesses an approximate C2 symmetry.展开更多
基金Project supported by the National Key R&D Program of China (Grant No.2022YFA1405500)the National Natural Science Foundation of China (Grant Nos.52372257 and 52072188)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University (Grant No.IRT-15R23)the Zhejiang Provincial Science and Technology Innovation Team (Grant No.2021R01004)。
文摘Element superconductors with the single atoms provide clean and fundamental platforms for studying superconductivity.Although elements with d electrons are usually not favored by conventional BCS,the record superconducting critical temperature(T_(c))in element scandium(S_(c))has further ignited the intensive attention on transition metals.The element molybdenum(M_o)with a half-full d-orbital is studied in our work,which fills the gap in the study of Mo under high pressure and investigates the pressure dependence of superconductivity.In this work,we exhibit a robust superconductivity of Mo in the pressure range of 5 GPa to 160 GPa via high-pressure electrical transport measurements,the T_(c) varies at a rate of0.013 K/GPa to 8.56 K at 160 GPa.Moreover,the superconductivity is evidenced by the T_(c) shifting to lower temperature under applied magnetic fields,and the upper critical magnetic fields are extrapolated by the WHH equation and GL equation;the results indicate that the maximum upper critical magnetic field is estimated to be 8.24 T at 137 GPa.We further investigate the superconducting mechanism of Mo,the theoretical calculations indicate that the superconductivity can be attributed to the strong coupling between the electrons from the partially filled d band and the phonons from the frequency zone of 200-400 cm^(-1).
基金financially supported by the National Natural Science Foundation of China (No.51964046)。
文摘The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.
基金financially supported by the National Natural Science Foundation of China (51504066).
文摘In a single sample plot,the total amount of heavy metals in the soil could not necessarily reflect the contents of their effective states.This must be considered when attempting to determine the degree of soil heavy-metal pollution in an area.In the present study,the soil around the molybdenum mining area in Huludao,China,was surveyed and sampled to evaluate soil heavy-metal pollution using the Nemerow multifactor pollution index method.The Tessier continuous extraction method was used to analyze the distribution of heavy-metal forms'and their content changes in the soil of this area.Thus,the bioactivity of heavy metals in the soil,the absorption of heavy metals by plants,and the distribution of heavy metals in plants were explored to provide data supporting the use of phytoremediation technology to treat the heavy-metal pollution in the molybdenum mining area and develop ecological restoration strategies for the area's wastelands.The pollution index results indicate that heavy-metal pollution in the soil around the tailings pond is severe,mainly due to Pb and Zn heavy metals.Heavy-metal pollution in the surrounding land is mainly due to Cd and Zn.Content analysis of the heavy-metal forms/states in soils shows that exchangeable forms,which are most effective and toxic to plants,of the following metals are highest in the following areas:Cd,Cu,and Zn in the mountains around the stope;Zn,Mo,and Cu in the cultivated land around the dump;and Cd,Zn,and Mo in the cultivated land around the tailings pond.The pollution index analysis provides a basic overview of soil heavy-metal pollution across the entire mining area.However,content analysis of heavy-metal forms/states better reflects the relationship between the availability of heavy metals in the soil and the effectiveness of plants.Thus,the latter analysis can help ensure that phytoremediation strategies are adequately targeted,science-based,and effective.
基金National Natural Science Foundation of China(21872101,21962014)Science and Technology Program of Zungeer County,Inner Mongolia(2020YY-12)。
文摘Selective synthesis of ethanol from syngas under the Co-based catalysts is still challenging due to the hard of regulating the active site Co^(0) and Co^(2+)ratio.In this work,a series of CaTi_(0.9-x)Co_(x)Mo_(0.1)O_(3)(x=0,0.1-0.4)and CaTi_(0.7)Co_(0.3)O_(3) catalysts were prepared by using citric acid complexation method to promote the synthesis of ethanol.It was found that Mo species in the perovskite lattice can regulate the Co^(0) and Co^(2+)ratio through the domain-limiting effect of perovskite and the degree of Co reduction could be adjusted by changing the Co/Mo molar ratio.Among these investigated catalysts,the total selectivity of alcohols over the catalyst with the optimal Co/Mo ratio CaTi_(0.6)Co_(0.3)Mo_(0.1)O_(3) reached 39.1%,with ethanol accounting for 74.7%,which was ascribed to the moderate and tightly bound ratio of dissociative to non-dissociative adsorption sites on the surface and the balance of CH_(x)-CH_(y) coupling and C^(O) insertion.
基金the Italian Ministry of University and Research(MUR)through the“Rita Levi Montalcini 2018”Fellowship(Grant number PGR18MAZLI)ENEA–UNIMIB PNRR agreement(Attività1.1.3 del PNRR POR H2)+1 种基金the Ministry of Science and Technology(State of Israel)and the Ministry of Foreign Affairs and International Cooperation–Directorate General for Cultural and Economic Promotion and Innovation(Italian Republic),respectively,within the bilateral project Italy-Israel(WE-CAT)the Italian ministry MUR for funding through the FISR 2019 project AMPERE(FISR2019_01294)。
文摘Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction(HER)occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed.Therefore,efficient platinum group metals(PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded.In this scenario,molybdenum disulfide(MoS_(2))owing to efficacious structural attributes and optimum hydrogen-binding free energy(ΔG_(H*))is emerging as a reliable alternative to PGMs.However,the performance of MoS_(2)-based electrocatalysts is still far away from the benchmark performance.The HER activity of MoS_(2)can be improved by engineering the structural parameters i.e.,doping,defects inducement,modulating the electronic structure,stabilizing the 1 T phase,creating nanocomposites,and altering the morphologies using appropriate fabrication pathways.Here,we have comprehensively reviewed the majority of the scientific endeavors published in recent years to uplift the HER activity of MoS_(2)-based electrocatalysts using different methods.Advancements in the major fabrication strategies including hydrothermal synthesis methods,chemical vapor deposition,exfoliation techniques,plasma treatments,chemical methodologies,etc.to tune the structural parameters and hence their ultimate influence on the electrocatalytic activity in acidic and/or alkaline media have been thoroughly discussed.This study can provide encyclopedic insights about the fabrication routes that have been pursued to improve the HER performance of MoS_(2)-based electrocatalysts.
基金supported by the National Natural Science Foundation of China(No.61805134 and No.11974229)Applied Basic Research Program in Shanxi Province,China(No.201801D221016 and No.202103021223254)+2 种基金Scientific and Technological Innovation Pro-grams of Higher Education Institutions in Shanxi(No.2020L0235 and No.2021L257)Linfen Key Re-search and Development Program(No.2028)Graduate Innovation Project in Shanxi Province(No.2022Y498).
文摘Zero-dimensional environmentally friendly carbon quantum dots(CQDs)combined with two-di-mensional materials have a wide range of applications in optoelec-tronic devices.We combined steady-state and transient absorp-tion spectroscopies to study the energy transfer dynamics between CQDs and molybdenum disulfide(MoS_(2)).Transient absorption plots showed photoinduced absorption and stimulated emission features,which involved the intrinsic and defect states of CQDs.Adding MoS_(2)to CQDs solution,the lowest unoccupied molecular orbital of CQDs transferred energy to MoS_(2),which quenched the intrinsic emission at 390 nm.With addition of MoS_(2),CQD-MoS_(2)composites quenched defect emission at 490 nm and upward absorption,which originated from another energy transfer from the defect state.Two energy transfer paths between CQDs and MoS_(2)were efficiently manipulated by changing the concentration of MoS_(2),which laid a foundation for improving device performance.
基金the financial support from the National Natural Science Foundation of China(51802269).
文摘Metal-ion capacitors could merit advantages from both batteries and capacitors,but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific capacitance of capacitor type electrode for both high energy and power density.Herein,we use the Kirkendall effect for the first time to synthesize unique tubular hierarchical molybdenum dioxide with encapsulated nitrogen-doped carbon sheets while in situ realizing phosphorus-doping to create rich oxygen vacancies(P-MoO_(2-x)@NP-C)as a sodium-ion electrode.Experimental and theoretical analysis confirm that the P-doping introduced oxygen defects can partially convert the high-bond-energy Mo–O to low-bond-energy Mo–P,resulting in a low oxidation state of molybdenum for enhanced surface reactivity and rapid reaction kinetics.The as-prepared P-MoO_(2-x)@NP-C as an ion-battery electrode is further used to pair active N-doped carbon nanosheet(N-C-A)electrode for Na-ion hybrid capacitor,delivering excellent performance with an energy density of 140.3 Wh kg^(−1),a power density of 188.5 W kg^(−1)and long stable life in non-aqueous solution,which ranks the best among all reported MoO x-based hybrid capacitors.P-MoO_(2-x)@NP-C is also used to fabricate a zinc-ion hybrid capacitor,also accomplishing a remarkable energy density of 43.8 Wh kg^(−1),a power density of 93.9 W kg^(−1),and a long stable life@2A g^(−1)of 32000 cycles in aqueous solutions,solidly verifying its universal significance.This work not only demonstrates an innovative approach to synthesize high-performance metal ion hybrid capacitor materials but also reveals certain scientific insights into electron transfer enhancement mechanisms.
基金This study was jointly funded by a project of the National Natural Science Foundation of China(42102087)a project of the China Postdoctoral Science Foundation(2022M712966)a key special project of the Ministry of Science and Technology of China(2021QZKK0304).
文摘The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with total molybdenum reserves of 1.65 billion tons,an average molybdenum ore grade of 0.081%,and molybdenum resources of 1.09 million tons.The main ore body is housed in the granodiorite porphyry plutons and their surrounding inequigranular granodiorite plutons,with high-grade ores largely located in the ore-bearing granodiorite porphyries in the middle-upper part of the porphyry plutons.Specifically,it appears as an ore pipe with a large upper part and a small lower part,measuring about 1700 m in length and width,extending for about 500 m vertically,and covering an area of 2.3 km^(2).Mineralogically,the main ore body consists of molybdenite,chalcopyrite,and sphalerite horizontally from its center outward and exhibits molybdenite,azurite,and pyrite vertically from top to bottom.The primary ore minerals include pyrite and molybdenite,and the secondary ore minerals include sphalerite,chalcopyrite,tetrahedrite,and scheelite,with average grades of molybdenum,copper,sulfur,gallium,and rhenium being 0.081%,0.033%,1.67%,0.001%,and 0.0012%,respectively.The ore-forming fluids of the Daheishan deposit originated as the CO_(2)-H_(2)O-NaCl multiphase magmatic fluid system,rich in CO_(2)and bearing minor amounts of CH4,N2,and H2S,and later mixed with meteoric precipitation.In various mineralization stages,the ore-forming fluids had homogenization temperatures of>420℃‒400℃,360℃‒350℃,340℃‒230℃,220℃‒210℃,and 180℃‒160℃and salinities of>41.05%‒9.8%NaCleqv,38.16%‒4.48%NaCleqv,35.78%‒4.49%NaCleqv,7.43%NaCleqv,and 7.8%‒9.5%NaCleqv,respectively.The mineralization of the Daheishan deposit occurred at 186‒167 Ma.The granites closely related to the mineralization include granodiorites(granodiorite porphyries)and monzogranites(monzogranite porphyries),which were mineralized after magmatic evolution(189‒167 Ma).Moreover,these mineralization-related granites exhibit low initial strontium content and high initial neodymium content,indicating that these granites underwent crust-mantle mixing.The Daheishan deposit formed during the Early-Middle Jurassic,during which basaltic magma underplating induced the lower-crust melting,leading to the formation of magma chambers.After the fractional crystallization of magmas,ore-bearing fluids formed.As the temperature and pressure decreased,the ore-bearing fluids boiled drops while ascending,leading to massive unloading of metal elements.Consequently,brecciated and veinlet-disseminated ore bodies formed.
基金supported by the Start-up grant from Suzhou University of Science and Technology.
文摘Currently the catalysis of hydrogen evolution reaction(HER)is mainly focused on the inherent electrocatalytic activity at relatively lower current densities while scarce at high current densities.Nevertheless,the latter is highly demanding in efficient mass-production of hydrogen.A SiO_(2) nanospheres template-synthesis is used to prepare mesoporous molybdenum carbide nanocrystals-embedded nitrogen-doped carbon foams(mp-Mo_(2)C/NC).The material shows much more excellent catalytic activity than the non-etched Mo_(2)C/NC toward hydrogen evolution reaction(HER)in acidic medium.More interestingly mp-Mo_(2)C/NC still has larger overpotential than Pt/C at lower current densities,but possess remarkably smaller overpotential than the latter at higher current densities for much better electrocatalytic performance.An approach is developed to investigate the electrode kinetics by Tafel plots,especially with eliminating the diffusion effect,indicating that Pt/C and mp-Mo_(2)C/NC display different reaction mechanisms.At low current densities the former presents reversible reaction,while the latter shows mixed electrochemical polarization/reversible electrode process.In the region of higher current densities,the former becomes totally gas-diffusion controlled with large overpotential,while the latter can still retain an electrode polarization process for much lower overpotential at the same current density.Result endorses that the meso-porously structured mp-Mo_(2)C/NC plays a critical role in avoiding gas diffusion control-resulting large overpotential at high current densities.This work holds great potential for an inexpensive catalyst better than Pt/C in practical applications of mass-production hydrogen at high current densities,while clearly shedding fundamental lights on designs of rational HER catalysts for the uses at high current densities.
文摘The properties of a metal-oxide-semiconductor device on a single layer MoS_(2)(molybdenum disulfide)semiconductor are determined theoretically utilizing the concept of physics that the carrier effective masses in materials are related to the intrinsic Fermi energy levels in materials by the universal mass-energy equivalence equation given as dE/E=dm/m,where E is the energy and m is the mass of the free electron.The known parameters of electron effective mass of 0.48 m and the direct bandgap of 1.8 eV for monolayer MoS_(2) semiconductor are utilized to determine the properties of the MOS(metal-oxide-semiconductor)device,with the given previous research consequence that the threshold for electron heating in SiO_(2) is 2 MV/cm-eV.
文摘A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear MoDDCs.This control assists in the tailoring of specific tribological properties of the MoDDCs in both greases and lubricating oils.
基金financially supported by the High-degree Talent Introduction Program of Guangdong Academy of Sciences(No.2017GDASCX-0841)the Science and Technology Program of Guangzhou(No.201607020021)+2 种基金the National Natural Science Foundation of China(No.51304055)the Innovative Platform Construction Program of Guangdong Academy of Sciences(No.2017GDASCX-0109)the Pearl River Nova Program of Guangzhou(No.201806010016)
文摘The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.
基金financially supported by the National Natural Science Foundation of China (No. 21425312, 21688102, 21621063, and 21573224)
文摘Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.
基金support by China Geological Survey (1212010911028)NSFC(40802020)+1 种基金Ministry of Land and Resources(1212010633902,1212010633903 and 121201 0711814)CUGB(GPMR 0735)
文摘The Wurinitu molybdenum deposit,located in Honggor,Sonid Left Banner of Inner Mongolia,China,is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite.The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation.LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons,one were formed at 181.7±7.4 Ma and the other at 133.6±3.3 Ma.The latter age is beli...
基金This work was financially supported by the National Key Fundamental Research Program (973) G1998061316 and theYoung Researcher
文摘Several kinds of tungsten thermonic cathodes have been introduced. As a promising alternative for thoriated tungsten, rare earth doped molybdenum cathode has been studied. Compared with the traditional thoriated tungsten, La- Mo cathode has higher emission current density at lower temperature, but it has poor emission stability. In order to im- prove the emission stability, systematical Study on the emission mechanism of La-Mo cathode has been carried out. The life of La-Mo cathode has been improved and has achieved 1400 h, which exceeds the minimum life for practical uses (1000 h). As another alternative for thoriated tungsten cathode, Y-Mo cathode has shown better performance. The ther- mionic emission capability of Y-Mo cathode is between that of La-Mo cathode and Th-W cathode.
文摘The chemiluminescence (CL) reaction between lucigenin (Lu) and molybdenum (III) produced by a Jones rcductor was investigated using a flow injection system. On the basis of this, a novel method for the determination of trace amount of molybdenum has been established. The emission intensity was linear with molybdenum concentration in the range of 0.1-1000ng/mL; the detection limit was 0.02 ng/mL molybdenum, the relative standard deviation was less than 2% for the determination of 0.1 ng/mL molybdenum (n=11). The method has been applied successfully to the analysis of trace molybdenum in water and steel samples.
文摘Hypoeutectic Fe-Cr-B-C hardfacing alloys with different molybdenum( Mo) contents( The design content was 0,2,3. 3 and 4. 5 wt. %,respectively) were deposited using the flux-cored wire by means of metal active gas arc welding. The effects of Mo on the refinement of microstructures,eutectic microstructure changes and improvement of wear resistance were investigated. The main results were shown as follows: the added Mo could increase the volume fraction of eutectic microstructure and reduce the size of coarse primary austenite as well as the volume fraction. The carboboride of M_3( B,C) could be observed in hypoeutectic Fe-Cr-B-C hardfacing alloys at the Mo design content of ≤2. 0 wt. %,while that of M_(23)( B,C)_(6) was formed when 3. 3 wt. % Mo was added.Additionally,the wear resistance of alloys was increased with the increase in Mo content. Specifically,the highest wear resistance of alloys was achieved at 4. 5 wt. % Mo design content,which was 113. 7% higher than that in alloys without Mo.
基金supported by the National Magnetic Confinement Fusion Science Program of China (No. 2017YFE0301304)National Natural Science Foundation of China (Nos. 11 475 039, 11 605 023, 11 705 020)+2 种基金China Postdoctoral Science Foundation (Nos. 2016M591423, 2017T100172, 2018M630285)the Fundamental Research Funds for the Central Universities (Nos. DUT15RC(3)072, DUT17RC(4)53, DUT18LK38)Liaoning Provincial Natural Science Foundation of China (No. 20 170 540 153)
文摘An experimental setup has been designed and realized in order to optimize the characteristics of laser-induced breakdown spectroscopy system working in various pressure environments. An approach combined the normalization methods with the partial least squares(PLS) method are developed for quantitative analysis of molybdenum(Mo) element in the multi-component alloy,which is the first wall material in the Experimental Advanced Superconducting Tokamak. In this study, the different spectral normalization methods(total spectral area normalization,background normalization, and reference line normalization) are investigated for reducing the uncertainty and improving the accuracy of spectral measurement. The results indicates that the approach of PLS based on inter-element interference is significantly better than the conventional PLS methods as well as the univariate linear methods in the various pressure for molybdenum element analysis.
文摘The complex (Bu4N) 2 [Mo2O5 (mp)2] was synthesized by the reactionof (Bu4N)2[Mo8O26] with H2mp (H2mp=o-mercaptophenol) in methanol. The molecular formula is C44H80Mo2N2O7S2, M.=1005.10. The complex is crystallized in monoclinic, space group P21/n with unit cell parameters, a = 17. 829 (2) A, b= 13. 759 (2 )A,c= 21. 974(2) A, g=105. 386(8)°, V= 5197. 4(1) , Dc= 1. 285 g/cm3, Z=4,λ(MoKa) =0. 71073 , μ=0. 607 mm-1,F(000) = 2120, final R=0.0348 and wR=0. 0741 for 4912 independent observed reflections (FM>4σ(Fo) ). Two MoO5S units inthe complex molecule exhibits the con facial distorted bioctahedral geometry and possesses an approximate C2 symmetry.
