Vanadium redox flow batteries(VRFBs)are a means of large-scale energy storage due to their excellent scalability,safety,long cycling life,and decoupled power and energy capacities.However,the slow redox kinetics of va...Vanadium redox flow batteries(VRFBs)are a means of large-scale energy storage due to their excellent scalability,safety,long cycling life,and decoupled power and energy capacities.However,the slow redox kinetics of vanadium species on conventional carbon electrodes remains a major limitation to their performance.We investigated the deposition of carbon black,carbon nanotubes,and electrochemically exfoliated graphene(Exf-Gr)onto thermally-activated carbon paper(ACP)by spray coating to increase the electrode electrocatalytic activity.The modified electrodes were characterized using scanning electron microscopy,X-ray diffraction,Raman spectroscopy,X-ray photoelectron microscopy,and surface area analysis,while their electrochemical properties were evaluated by cyclic voltammetry,electrochemical impedance spectroscopy,and singlecell VRFB testing.Among the modified electrodes,Exf-Gr/ACP had the best performance,achieving a 2.9-fold reduction in charge transfer resistance compared to pristine ACP and delivering 2.5 times the discharge capacity in single-cell tests.This improvement is attributed to Exf-Gr’s high surface area,favorable catalytic activity,and excellent dispersion on the ACP substrate.Surface modification with electrochemically exfoliated graphene is a highly effective strategy for improving the electrode performance in VRFB systems,with significant implications for large-scale energy storage.展开更多
Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates wi...Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates with varying manganese concentrations(VL-cMn)were prepared through calcium,a calcium-manganese composite,and manganese-based roasting of vanadium slag(VS)to investigate the influence of manganese on vanadium precipitation behavior during hydrolysis precipitation(HP)and ammonium salt precipitation(AP),as well as the microscopic characteristics and purity of the resulting V_(2)O_(5) products.The results showed that increasing the pH mitigated the negative effects of Mn on the V precipitation rate during HP.However,as the manganese concentration increased from 5.69 to 15.38 g/L,the V precipitation rate gradually declined at higher temperatures and longer reaction times.The precipitates exhibited increased microstructural density,which might had contributed to the formation of Mn-bearing phases.Additionally,the average grain size of V_(2)O_(5) was reduced and the particles were increasingly agglomerated,leading to a 2.55%decrease in product purity.For AP,as manganese concentration increased,raising the pH counteracted the negative impact of Mn on the V precipitation rate and reduced the required amount of ammonium sulfate.Moreover,Mn was unevenly adsorbed on the surface of the precipitates.Although V_(2)O_(5) grains gradually shrank and became denser,there was no significant effect on the final product purity,which remained above 99.3%.In conclusion,roasting with added manganese salts influenced the hydrolysis of vanadium but had no significant effect on acidic ammonium salt precipitation.展开更多
It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,...It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).展开更多
The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment...The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment process was used to increase the fine-grained content and specific surface area of VTM concentrates,to strengthen the oxidation consolidation process of VTM pellets,and oxidation kinetic experiments were carried out.The results showed that the specific surface area of VTM concentrates was increased from 872 to 1457 cm^(2)/g by HPGR and then pelletising and roasting.With preheating at 1000℃ for 10 min and roasting at 1260℃ for 10 min,the strengths of preheated pellets were increased from 329 to 535 N,and the strengths of roasted pellets were increased from 1010 to 2591 N.The limiting link in the early stage of VTM pellets oxidation was the control of chemical reaction,while the limiting link in the later stage of oxidation was the mixed control of chemical reaction and gas diffusion.The activation energies of VTM pellets before and after HPGR pretreatment were 53.07 and 40.03 kJ/mol in the early stage of oxidation reaction,while the activation energies in the later stage of oxidation were 29.24 and 22.75 kJ/mol,respectively.展开更多
Vanadium redox flow battery(VRFB),as a potential technology for next-generation energy storage system,is restricted by the slow redox kinetics of vanadium ions.Implementing interface engineering strategies to function...Vanadium redox flow battery(VRFB),as a potential technology for next-generation energy storage system,is restricted by the slow redox kinetics of vanadium ions.Implementing interface engineering strategies to functionalize the surface of MXene can effectively address this challenge.Herein,a Nb_(2)CT_(x)/Nb_(2)O_(5)Schottky heterostructure is constructed to facilitate high-speed charge transfer at the VRFB electrode through controllable in-situ oxidation.The loading amount of Nb_(2)O_(5) nanorods on the surface of Nb_(2)CT_(x) nanosheets was regulated by varying the hydrothermal reaction time.Density functional theory calculations confirm that the Schottky barrier formed between Nb_(2)CT_(x) and Nb_(2)O_(5) leads to the establishment of an internal electric field and reconfigures the electronic structure of surficial active sites.The rich pore structure of Nb_(2)CT_(x)/Nb_(2)O_(5) electrode effectively shortens the diffusion path for vanadium ions,while its excellent hydrophilicity enhances the interaction between vanadium ions and the electrodes.Compared with graphite felt,Nb_(2)CT_(x)/Nb_(2)O_(5)-2@GF cell shows a 20%increase in energy efficiency(EE)at 150 mA cm^(-2) cycling,reaching 75%,while maintaining stable performance for over 800 cycles.This means a significant advancement in the development of high-performance electrodes for VRFBs.This work offers an efficient and scalable strategy for the design of redox flow batteries.展开更多
Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochem...Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochemical methods with only several reports.This study pioneers an electrocatalytic strategy for the efficient synthesis of THFDCA via the oxidation of tetrahydrofuran dimethanol(THFDM).By constructing NiCo bimetallic oxides micron sheets on nickel foam(NiCoMS/NF)through controlled pyrolysis of a metal-organic framework(MOF)-like precursor,we achieved a remarkable THFDM conversion of 99.0%and THFDCA yield up to 98.2%,surpassing all reports on thermocatalytic oxidation as we know.In-depth analysis revealed that the synergistic effect between NiO and Co_(3)O_(4) contributes to the high catalytic performance.In-situ Raman and rotating ring-disk electrode(RRDE)techniques were employed to discuss the reaction mechanism and the inhibitory effect on oxygen evolution reaction(OER).This study not only provides a paradigm-shifting,groundbreaking strategy for the synthesis of the flexible cyclic dicarboxylic acid derived from furanic biomass but also offers deep insights into the synergistic effects of electrocatalysts.展开更多
The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are co...The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are considered as prospective alternatives for the cathode of a new generation of lithium-ion batteries.However,the poor rate and cycling performance caused by the sluggish electrons/lithium transportation,irreversible phase changes,vanadium dissolution and large volume changes during the repeated lithium intercalation/deintercalation hinder their commercial development.Several optimizing routes have been carried out and extensively explored to address these problems.Taking V_(2)O_(5),VO_(2)(B),V_(6)O_(13),and V_(2)O_(3)as examples,this article reviewed their crystal structures and lithium storage reactions.Besides,recent progress in modification methods for the electrochemical insufficiencies of vanadium oxides,including nanostructure,heterogeneous atom doping,composite and self-supported electrodes has been systematically summarized and finally,the challenges for the industrialization of vanadium oxide cathodes and their development opportunities are proposed.展开更多
Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium ox...Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium oxides exhibit great potentiality.Vanadium oxides can provide multiple electron transfers during electrochemical reactions because vanadium possesses a variety of oxidation states.Meanwhile,their relatively low cost and superior material,structural,and physicochemical properties endow them with strong competitiveness.Although some inspiring research results have been achieved,many issues and challenges remain to be further addressed.Herein,we systematically summarize the research progress of vanadium oxides for PIBs.Then,feasible improvement strategies for the material properties and electrochemical performance are introduced.Finally,the existing challenges and perspectives are discussed with a view to promoting the development of vanadium oxides and accelerating their practical applications.展开更多
Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic chara...Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.展开更多
Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely...Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.展开更多
Vanadium redox flow battery(VRFB)is a kind of battery with wide application prospect.Electrode material is one of the key components of VRFB,and its stability directly affects the performance of battery.Among all kind...Vanadium redox flow battery(VRFB)is a kind of battery with wide application prospect.Electrode material is one of the key components of VRFB,and its stability directly affects the performance of battery.Among all kinds of electrode materials,carbon-based material has the best comprehensive properties.However,carbon-based electrodes still have disadvantages such as poor hydrophilicity and low electrochemical activity which need to be improved.One of the effective ways to improve the performance of electrode is to modify carbon-based material with metals and metal oxides.The metal catalysts have excellent electrical conductivity and high catalytic activity.The metal oxide catalysts have the advantages of low cost,wide variety and strong oxidizing properties.This work introduced the application of metal and metal oxide modified electrodes in VRFB in recent years,classified the catalysts,studied their catalytic performance and mechanism.The metal catalysts were reviewed from precious metals and base metals.The metal oxide catalysts were classified and discussed according to the similar properties of the same group elements.This work compared different modification methods,summarized the research progress of metal and metal oxide modification,and proposes the future development direction of electrodes and catalysts.展开更多
A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound cry...A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound crystallizes ina monoclinic space group P2（1）/n with a = 1.0254（2） nm, b =0.6739（2） nm, c = 1.2400（2） nm, ,8 = 93.88 （ 3 ） °, V = 0. 8549 （ 3 ）nm^3, Z = 2, R1 = 0. 0366, wR2 = 0. 1038. Compound 1 consists of two-dimensional mixed-valence vanadium oxide layers parallelling to the bc plane. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.展开更多
The desulfurization and resulfurization of slag containing oxides of vanadium and titanium(CaO–SiO_(2)–MgO–Al_(2)O_(3)–V_(2)O_(3)–TiO_(2)–FeO)in the pretreatment of semi-steel desulfurization at 1623 K were inve...The desulfurization and resulfurization of slag containing oxides of vanadium and titanium(CaO–SiO_(2)–MgO–Al_(2)O_(3)–V_(2)O_(3)–TiO_(2)–FeO)in the pretreatment of semi-steel desulfurization at 1623 K were investigated.Based on the ionic structure theory of slag,it could be concluded that V_(2)O_(3) and TiO_(2) combined with(O_(2)–)to form complex anions including VO_(3)^(3–),TiO_(4)^(4–),etc.,which reduced the activity of(O_(2)–)and decreased the sulfur partition ratio(LS).And FeO enhanced the activity of[O]at the slag–metal interface,which decreased the desulfurization capacity of the slag.Compared to the binary basicity,the presented basicity expression containing V_(2)O_(3) and TiO_(2) described the relationship between LS and basicity more accurately.Considering the problems of dilute slag,a large amount of residual slag and much resulfurization in the slagging-off process after pretreatment,the effect of CaO+C-based slag modifier on the resulfurization,melting point and viscosity of the desulfurization slag was investigated.It was proposed that adding 5%–10%of the slag modifier to the desulfurization slag after desulfurization decreased the resulfurization effectively.And the added modifier adjusted the slag viscosity well,which helped to reduce iron loss and residual slag.展开更多
The influence of V2O3,FeO,TiO2,MnO and MgO in vanadium slag on the corrosion mechanism of MgO-C bricks was studied by stationary immersion tests at vanadium-extracting temperature.Experimental results show that FeO,Ti...The influence of V2O3,FeO,TiO2,MnO and MgO in vanadium slag on the corrosion mechanism of MgO-C bricks was studied by stationary immersion tests at vanadium-extracting temperature.Experimental results show that FeO,TiO2,and MnO could enhance the corrosion rate and V2O3 and MgO could decrease it.Microstructure and phase composition of worn samples were investigated by SEM-EDS,revealing the presence of Fe particles,produced by graphite reduction,and(Mg,Fe,Mn)O solid solution at the interface.The formation process of(Mg,Fe,Mn)O solid solution was discussed and the corrosion mechnism of MgO-C bricks was thus proposed.展开更多
As the steel industry expands worldwide,slag dumps with transition metals(especially chromium and vanadium)are becoming more common,posing a serious environmental threat.Understanding the properties of slags containin...As the steel industry expands worldwide,slag dumps with transition metals(especially chromium and vanadium)are becoming more common,posing a serious environmental threat.Understanding the properties of slags containing transition metal oxides,as well as how to use the slags to recover and recycle metal values,is critical.Toward this end,the University of Science and Technology Beijing(USTB)and Royal Institute of Technology(KTH)have been collaborating on slags containing transition metals for decades.The research was carried out from a fundamental viewpoint to get a better understanding of the structure of these slags and their properties,as well as industrial practices.The research focused on the three“R”s,viz.retention,recovery,and recycling.The present paper attempts to highlight some of the important achievements in these joint studies.展开更多
Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we...Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°C.The precursors were then calcined under nitrogen at various temperatures.The products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron spectroscopy.It was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°C.The size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was used.The sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume ratio.To the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 nanocrystals.The nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.展开更多
Aqueous multivalent-metal-ion intercalation chemistries hold genuine promise to develop safe and powerful microbatteries for potential use in many miniaturized electronics.However,their development is beset by state-o...Aqueous multivalent-metal-ion intercalation chemistries hold genuine promise to develop safe and powerful microbatteries for potential use in many miniaturized electronics.However,their development is beset by state-of-the-art electrode materials having practical capacities far below their theoretical values.Here we demonstrate that high compatibility between layered transition-metal oxide hosts and hydrated cation vips substantially boost their multi-electron-redox reactions to offer higher capacities and rate capability,based on typical bipolar vanadium oxides preintercalated with hydrated cations(M_(x)V_(2)O_(5)).When seamlessly integrated on Au current microcollectors with a three-dimensional bicontinuous nanoporous architecture that offers high pathways of electron transfer and ion transport,the constituent Zn_(x)V_(2)O_(5) exhibits specific capacity of as high as∼527 mAh g^(−1) at 5 mV s^(−1) and retains∼300 mAh g^(−1) at 200 mV s^(−1) in 1 M ZnSO_(4) aqueous electrolyte,outperforming the M_(x)V_(2)O_(5)(M=Li,Na,K,Mg).This allows aqueous rechargeable zinc-ion microbatteries constructed with symmetric nanoporous Zn_(x)V_(2)O_(5)/Au interdigital microelectrodes as anode and cathode to show high-density energy of∼358 mWh cm^(−3)(a value that is forty-fold higher than that of 4 V/500μAh Li thin film battery)at high levels of power delivery.展开更多
The reaction mechanism of thiophene on vanadium oxides under FCC operating conditions hadbeen preliminary studied using in-situ FT-IR analysis of thiophene and atmospheric pressure continuousfixed-bed reaction, follow...The reaction mechanism of thiophene on vanadium oxides under FCC operating conditions hadbeen preliminary studied using in-situ FT-IR analysis of thiophene and atmospheric pressure continuousfixed-bed reaction, followed by characterization via pyridine adsorption-temperature programmed desorptionmethod, and FT-IR and XPS spectra. The research had discovered that, under 500℃ thiophene could undergothe redox reaction with V2O5, while being converted into CO, CO2 as well as SO2 with its conversion ratereaching 41.2%. At the same time the oxidation number of vanadium decreased. The existence of a few Brnstedacid centers on V2O5 could lead to an increase of H2S yield among the products derived from the reaction withthiophene.展开更多
Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueo...Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V2O5 and vanadium（Ⅲ, Ⅳ） oxides. In the first 2 hr, the release rates of vanadium from V2O3 were r = 1.14·（[H＋]）-0.269 at pH 3.0–6.0 and r = 0.016·（[H＋]）-（-0.048） at pH 6.0–10.0; the release rates from VO2 were r = 0.362·（[H＋]）-0.129 at pH 3.0–6.0 and r = 0.017·（[H＋]）-（-0.097） at pH 6.0–10.0; and the release rates from V2O5 were r = 0.131·（[H＋]）--（0.104） at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium（Ⅲ, Ⅳ and Ⅴ） oxides（33.4–87.5 kJ/mol） were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.展开更多
To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were pre...To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were prepared by hydrothermal and subsequent heat treatment.The beginning hydrogen desorption temperature of 7 wt.%Ni_(3)V_(2)O_(8)-rGO modified MgH_(2)was reduced to 208℃,while the additive-free MgH_(2)and 7 wt.%Ni_(3)V_(2)O_(8)doped MgH_(2)appeared to discharge hydrogen at 340 and 226℃,respectively.A charging capacity of about 4.7 wt.%H_(2)for MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO was achieved at 125℃ in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215℃.The microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)N_(i)H_(4) and metallic V contributed significantly to the enhanced performance of MgH_(2).In addition,the presence of rGO in the MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO composite reduced particle aggregation tendency of Mg/MgH_(2),leading to improving the cyclic stability of MgH_(2)during 20 cycles.展开更多
基金supported by the University of Seoul’s 2025 Research Fund.
文摘Vanadium redox flow batteries(VRFBs)are a means of large-scale energy storage due to their excellent scalability,safety,long cycling life,and decoupled power and energy capacities.However,the slow redox kinetics of vanadium species on conventional carbon electrodes remains a major limitation to their performance.We investigated the deposition of carbon black,carbon nanotubes,and electrochemically exfoliated graphene(Exf-Gr)onto thermally-activated carbon paper(ACP)by spray coating to increase the electrode electrocatalytic activity.The modified electrodes were characterized using scanning electron microscopy,X-ray diffraction,Raman spectroscopy,X-ray photoelectron microscopy,and surface area analysis,while their electrochemical properties were evaluated by cyclic voltammetry,electrochemical impedance spectroscopy,and singlecell VRFB testing.Among the modified electrodes,Exf-Gr/ACP had the best performance,achieving a 2.9-fold reduction in charge transfer resistance compared to pristine ACP and delivering 2.5 times the discharge capacity in single-cell tests.This improvement is attributed to Exf-Gr’s high surface area,favorable catalytic activity,and excellent dispersion on the ACP substrate.Surface modification with electrochemically exfoliated graphene is a highly effective strategy for improving the electrode performance in VRFB systems,with significant implications for large-scale energy storage.
基金supported by National Natural Science Foundation of China(Nos.52204309,52174277 and 52374300)Fundamental Funds for the Central Universities(No.N2425026)。
文摘Manganese is a major impurity in acidic vanadium-bearing leaching solutions,but its effects on vanadium precipitation via hydrolysis and acidic ammonium salts remain unclear.In this study,vanadium-bearing leachates with varying manganese concentrations(VL-cMn)were prepared through calcium,a calcium-manganese composite,and manganese-based roasting of vanadium slag(VS)to investigate the influence of manganese on vanadium precipitation behavior during hydrolysis precipitation(HP)and ammonium salt precipitation(AP),as well as the microscopic characteristics and purity of the resulting V_(2)O_(5) products.The results showed that increasing the pH mitigated the negative effects of Mn on the V precipitation rate during HP.However,as the manganese concentration increased from 5.69 to 15.38 g/L,the V precipitation rate gradually declined at higher temperatures and longer reaction times.The precipitates exhibited increased microstructural density,which might had contributed to the formation of Mn-bearing phases.Additionally,the average grain size of V_(2)O_(5) was reduced and the particles were increasingly agglomerated,leading to a 2.55%decrease in product purity.For AP,as manganese concentration increased,raising the pH counteracted the negative impact of Mn on the V precipitation rate and reduced the required amount of ammonium sulfate.Moreover,Mn was unevenly adsorbed on the surface of the precipitates.Although V_(2)O_(5) grains gradually shrank and became denser,there was no significant effect on the final product purity,which remained above 99.3%.In conclusion,roasting with added manganese salts influenced the hydrolysis of vanadium but had no significant effect on acidic ammonium salt precipitation.
文摘It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).
基金supports provided from Guangxi Science and Technology Major Project(AA24263047).
文摘The production of vanadium-titanium magnetite(VTM)pellets has the problems of low consolidation strength and high energy consumption in the preheating and roasting process.High-pressure grinding roll(HPGR)pretreatment process was used to increase the fine-grained content and specific surface area of VTM concentrates,to strengthen the oxidation consolidation process of VTM pellets,and oxidation kinetic experiments were carried out.The results showed that the specific surface area of VTM concentrates was increased from 872 to 1457 cm^(2)/g by HPGR and then pelletising and roasting.With preheating at 1000℃ for 10 min and roasting at 1260℃ for 10 min,the strengths of preheated pellets were increased from 329 to 535 N,and the strengths of roasted pellets were increased from 1010 to 2591 N.The limiting link in the early stage of VTM pellets oxidation was the control of chemical reaction,while the limiting link in the later stage of oxidation was the mixed control of chemical reaction and gas diffusion.The activation energies of VTM pellets before and after HPGR pretreatment were 53.07 and 40.03 kJ/mol in the early stage of oxidation reaction,while the activation energies in the later stage of oxidation were 29.24 and 22.75 kJ/mol,respectively.
基金financially supported by the National Natural Science Foundation of China(22578113 and 52371187)Natural Science Foundation of Hebei Province(E2024209029)Science and Technology Planning Project of Tangshan City(24130228C)。
文摘Vanadium redox flow battery(VRFB),as a potential technology for next-generation energy storage system,is restricted by the slow redox kinetics of vanadium ions.Implementing interface engineering strategies to functionalize the surface of MXene can effectively address this challenge.Herein,a Nb_(2)CT_(x)/Nb_(2)O_(5)Schottky heterostructure is constructed to facilitate high-speed charge transfer at the VRFB electrode through controllable in-situ oxidation.The loading amount of Nb_(2)O_(5) nanorods on the surface of Nb_(2)CT_(x) nanosheets was regulated by varying the hydrothermal reaction time.Density functional theory calculations confirm that the Schottky barrier formed between Nb_(2)CT_(x) and Nb_(2)O_(5) leads to the establishment of an internal electric field and reconfigures the electronic structure of surficial active sites.The rich pore structure of Nb_(2)CT_(x)/Nb_(2)O_(5) electrode effectively shortens the diffusion path for vanadium ions,while its excellent hydrophilicity enhances the interaction between vanadium ions and the electrodes.Compared with graphite felt,Nb_(2)CT_(x)/Nb_(2)O_(5)-2@GF cell shows a 20%increase in energy efficiency(EE)at 150 mA cm^(-2) cycling,reaching 75%,while maintaining stable performance for over 800 cycles.This means a significant advancement in the development of high-performance electrodes for VRFBs.This work offers an efficient and scalable strategy for the design of redox flow batteries.
基金supported by the National Natural Science Foundation of China(22072170,U23A20125)the President Foundation of Ningbo Institute of Materials Technology and Engineering。
文摘Tetrahydrofuran-2,5-dicarboxylic acid(THFDCA)is a bio-based cyclic dicarboxylic acid with greater flexibility and biosafety than the renowned 2,5-furandicarboxylic acid(FDCA),but its synthesis is limited to thermochemical methods with only several reports.This study pioneers an electrocatalytic strategy for the efficient synthesis of THFDCA via the oxidation of tetrahydrofuran dimethanol(THFDM).By constructing NiCo bimetallic oxides micron sheets on nickel foam(NiCoMS/NF)through controlled pyrolysis of a metal-organic framework(MOF)-like precursor,we achieved a remarkable THFDM conversion of 99.0%and THFDCA yield up to 98.2%,surpassing all reports on thermocatalytic oxidation as we know.In-depth analysis revealed that the synergistic effect between NiO and Co_(3)O_(4) contributes to the high catalytic performance.In-situ Raman and rotating ring-disk electrode(RRDE)techniques were employed to discuss the reaction mechanism and the inhibitory effect on oxygen evolution reaction(OER).This study not only provides a paradigm-shifting,groundbreaking strategy for the synthesis of the flexible cyclic dicarboxylic acid derived from furanic biomass but also offers deep insights into the synergistic effects of electrocatalysts.
基金supported by the National Natural Science Foundation of China,NSFC(51772205,51772208)the General Program of Municipal Natural Science Foundation of Tianjin(17JCYBJC17000,17JCYBJC22700)。
文摘The emergency of high-power electrical appliances has put forward higher requirements for the power density of lithium-ion batteries.Vanadium oxides with large theoretical capacities and high operating voltages are considered as prospective alternatives for the cathode of a new generation of lithium-ion batteries.However,the poor rate and cycling performance caused by the sluggish electrons/lithium transportation,irreversible phase changes,vanadium dissolution and large volume changes during the repeated lithium intercalation/deintercalation hinder their commercial development.Several optimizing routes have been carried out and extensively explored to address these problems.Taking V_(2)O_(5),VO_(2)(B),V_(6)O_(13),and V_(2)O_(3)as examples,this article reviewed their crystal structures and lithium storage reactions.Besides,recent progress in modification methods for the electrochemical insufficiencies of vanadium oxides,including nanostructure,heterogeneous atom doping,composite and self-supported electrodes has been systematically summarized and finally,the challenges for the industrialization of vanadium oxide cathodes and their development opportunities are proposed.
基金the Shenyang University of Technology(QNPY202209-4)the Key R&D project of Liaoning Province of China(2020JH2/10300079)+2 种基金the“Liaoning BaiQianWan Talents Program”(2018921006)the Liaoning Revitalization Talents Program(XLYC1908034)the National Natural Science Foundation of China(21571132).
文摘Potassium-ion batteries(PIBs)have been considered as promising candidates in the post-lithium-ion battery era.Till now,a large number of materials have been used as electrode materials for PIBs,among which vanadium oxides exhibit great potentiality.Vanadium oxides can provide multiple electron transfers during electrochemical reactions because vanadium possesses a variety of oxidation states.Meanwhile,their relatively low cost and superior material,structural,and physicochemical properties endow them with strong competitiveness.Although some inspiring research results have been achieved,many issues and challenges remain to be further addressed.Herein,we systematically summarize the research progress of vanadium oxides for PIBs.Then,feasible improvement strategies for the material properties and electrochemical performance are introduced.Finally,the existing challenges and perspectives are discussed with a view to promoting the development of vanadium oxides and accelerating their practical applications.
基金This work was supported by the National Science Foundation(CBET-1803256)Dr.C.Liu acknowledges the support from National Natural Science Foundation of China(52102277)the Fundamental Research Funds for the Central Universities,conducted by Tongji University.
文摘Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.
基金the financial support from the National Key Research and Development Program of China(2022YFA1207503)the Giga Force Electronics Interdisciplinary Funding(JJHXM002208-2023)。
文摘Exploring suitable high-capacity V_(2)O_(5)-based cathode materials is essential for the rapid advancement of aqueous zinc ion batteries(ZIBs).However,the typical problem of slow Zn^(2+)diffusion kinetics has severely limited the feasibility of such materials.In this work,unique hydrated vanadates(CaVO,BaVO)were obtained by intercalation of Ca^(2+)or Ba^(2+)into hydrated vanadium pentoxide.In the CaVO//Zn and BaVO//Zn batteries systems,the former delivered up to a 489.8 mAh g^(-1)discharge specific capacity at 0.1 A g^(-1).Moreover,the remarkable energy density of 370.07 Wh kg^(-1)and favorable cycling stability yard outperform BaVO,pure V_(2)O_(5),and many reported cathodes of similar ionic intercalation compounds.In addition,pseudocapacitance analysis,galvanostatic intermittent titration(GITT)tests,and Trasatti analysis revealed the high capacitance contribution and Zn^(2+)diffusion coefficient of CaVO,while an in-depth investigation based on EIS elucidated the reasons for the better electrochemical performance of CaVO.Notably,ex-situ XRD,XPS,and TEM tests further demonstrated the Zn^(2+)insertion/extraction and Zn-storage mechanism that occurred during the cycle in the CaVO//Zn battery system.This work provides new insights into the intercalation of similar divalent cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity aqueous ZIBs.
基金the National Natural Science Foundation of China(Nos.51872090 and 51772097)the Hebei Natural Science Fund for Distinguished Young Scholar(Nos.E2019209433 and E2017209079)。
文摘Vanadium redox flow battery(VRFB)is a kind of battery with wide application prospect.Electrode material is one of the key components of VRFB,and its stability directly affects the performance of battery.Among all kinds of electrode materials,carbon-based material has the best comprehensive properties.However,carbon-based electrodes still have disadvantages such as poor hydrophilicity and low electrochemical activity which need to be improved.One of the effective ways to improve the performance of electrode is to modify carbon-based material with metals and metal oxides.The metal catalysts have excellent electrical conductivity and high catalytic activity.The metal oxide catalysts have the advantages of low cost,wide variety and strong oxidizing properties.This work introduced the application of metal and metal oxide modified electrodes in VRFB in recent years,classified the catalysts,studied their catalytic performance and mechanism.The metal catalysts were reviewed from precious metals and base metals.The metal oxide catalysts were classified and discussed according to the similar properties of the same group elements.This work compared different modification methods,summarized the research progress of metal and metal oxide modification,and proposes the future development direction of electrodes and catalysts.
基金Supported by the National Natural Science Foundation of China(No.20171010).
文摘A new layered vanadium oxide [ NH3 （ CH2 ）2NH（ CH2 ）2NH3 ] [ V6O14 ] （ compound 1 ） was synthesized and characterized by elemental analysis, IR spectrometry and single crystal X ray diffraction. The compound crystallizes ina monoclinic space group P2（1）/n with a = 1.0254（2） nm, b =0.6739（2） nm, c = 1.2400（2） nm, ,8 = 93.88 （ 3 ） °, V = 0. 8549 （ 3 ）nm^3, Z = 2, R1 = 0. 0366, wR2 = 0. 1038. Compound 1 consists of two-dimensional mixed-valence vanadium oxide layers parallelling to the bc plane. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.
文摘The desulfurization and resulfurization of slag containing oxides of vanadium and titanium(CaO–SiO_(2)–MgO–Al_(2)O_(3)–V_(2)O_(3)–TiO_(2)–FeO)in the pretreatment of semi-steel desulfurization at 1623 K were investigated.Based on the ionic structure theory of slag,it could be concluded that V_(2)O_(3) and TiO_(2) combined with(O_(2)–)to form complex anions including VO_(3)^(3–),TiO_(4)^(4–),etc.,which reduced the activity of(O_(2)–)and decreased the sulfur partition ratio(LS).And FeO enhanced the activity of[O]at the slag–metal interface,which decreased the desulfurization capacity of the slag.Compared to the binary basicity,the presented basicity expression containing V_(2)O_(3) and TiO_(2) described the relationship between LS and basicity more accurately.Considering the problems of dilute slag,a large amount of residual slag and much resulfurization in the slagging-off process after pretreatment,the effect of CaO+C-based slag modifier on the resulfurization,melting point and viscosity of the desulfurization slag was investigated.It was proposed that adding 5%–10%of the slag modifier to the desulfurization slag after desulfurization decreased the resulfurization effectively.And the added modifier adjusted the slag viscosity well,which helped to reduce iron loss and residual slag.
基金Item Sponsored by National Natural Science Foundation of China(51090382)
文摘The influence of V2O3,FeO,TiO2,MnO and MgO in vanadium slag on the corrosion mechanism of MgO-C bricks was studied by stationary immersion tests at vanadium-extracting temperature.Experimental results show that FeO,TiO2,and MnO could enhance the corrosion rate and V2O3 and MgO could decrease it.Microstructure and phase composition of worn samples were investigated by SEM-EDS,revealing the presence of Fe particles,produced by graphite reduction,and(Mg,Fe,Mn)O solid solution at the interface.The formation process of(Mg,Fe,Mn)O solid solution was discussed and the corrosion mechnism of MgO-C bricks was thus proposed.
基金Parts of the work were carried out as part of the Eco Steelmaking project funded by the Swedish Foundation for Strategic Environmental Research(MISTRA)through the Swedish Steel Producers AssociationChinese Academy of Science is acknowledged for its partial finical support through the“Transfer and commercialization of scientific and technological achievements”project(No.2020109)。
文摘As the steel industry expands worldwide,slag dumps with transition metals(especially chromium and vanadium)are becoming more common,posing a serious environmental threat.Understanding the properties of slags containing transition metal oxides,as well as how to use the slags to recover and recycle metal values,is critical.Toward this end,the University of Science and Technology Beijing(USTB)and Royal Institute of Technology(KTH)have been collaborating on slags containing transition metals for decades.The research was carried out from a fundamental viewpoint to get a better understanding of the structure of these slags and their properties,as well as industrial practices.The research focused on the three“R”s,viz.retention,recovery,and recycling.The present paper attempts to highlight some of the important achievements in these joint studies.
基金supported by the National Natural Science Foundation of China(21172269)Innovation Group of Hubei Natural Science Foundation(2018CFA023)Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(JDGD-201809)~~
文摘Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°C.The precursors were then calcined under nitrogen at various temperatures.The products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron spectroscopy.It was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°C.The size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was used.The sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume ratio.To the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 nanocrystals.The nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.
基金supported by the National Natural Science Foundation of China (Nos. 51871107, 52130101, 51631004)Top-notch Young Talent Program of China (W02070051)+2 种基金Chang Jiang Scholar Program of China (Q2016064)the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT, 2017TD-09)the Fundamental Research Funds for the Central Universities, the Program for Innovative Research Team (in Science and Technology) in University of Jilin Province。
文摘Aqueous multivalent-metal-ion intercalation chemistries hold genuine promise to develop safe and powerful microbatteries for potential use in many miniaturized electronics.However,their development is beset by state-of-the-art electrode materials having practical capacities far below their theoretical values.Here we demonstrate that high compatibility between layered transition-metal oxide hosts and hydrated cation vips substantially boost their multi-electron-redox reactions to offer higher capacities and rate capability,based on typical bipolar vanadium oxides preintercalated with hydrated cations(M_(x)V_(2)O_(5)).When seamlessly integrated on Au current microcollectors with a three-dimensional bicontinuous nanoporous architecture that offers high pathways of electron transfer and ion transport,the constituent Zn_(x)V_(2)O_(5) exhibits specific capacity of as high as∼527 mAh g^(−1) at 5 mV s^(−1) and retains∼300 mAh g^(−1) at 200 mV s^(−1) in 1 M ZnSO_(4) aqueous electrolyte,outperforming the M_(x)V_(2)O_(5)(M=Li,Na,K,Mg).This allows aqueous rechargeable zinc-ion microbatteries constructed with symmetric nanoporous Zn_(x)V_(2)O_(5)/Au interdigital microelectrodes as anode and cathode to show high-density energy of∼358 mWh cm^(−3)(a value that is forty-fold higher than that of 4 V/500μAh Li thin film battery)at high levels of power delivery.
文摘The reaction mechanism of thiophene on vanadium oxides under FCC operating conditions hadbeen preliminary studied using in-situ FT-IR analysis of thiophene and atmospheric pressure continuousfixed-bed reaction, followed by characterization via pyridine adsorption-temperature programmed desorptionmethod, and FT-IR and XPS spectra. The research had discovered that, under 500℃ thiophene could undergothe redox reaction with V2O5, while being converted into CO, CO2 as well as SO2 with its conversion ratereaching 41.2%. At the same time the oxidation number of vanadium decreased. The existence of a few Brnstedacid centers on V2O5 could lead to an increase of H2S yield among the products derived from the reaction withthiophene.
基金supported by the National Natural Science Foundation of China(Nos.21607166,41641034 and 41473113)the National Water Pollution Control and Treatment Science and Technology Major Project(No.2015ZX07205-003)
文摘Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium（Ⅲ, Ⅳ and Ⅴ） oxides at pH 3.1–10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V2O5 and vanadium（Ⅲ, Ⅳ） oxides. In the first 2 hr, the release rates of vanadium from V2O3 were r = 1.14·（[H＋]）-0.269 at pH 3.0–6.0 and r = 0.016·（[H＋]）-（-0.048） at pH 6.0–10.0; the release rates from VO2 were r = 0.362·（[H＋]）-0.129 at pH 3.0–6.0 and r = 0.017·（[H＋]）-（-0.097） at pH 6.0–10.0; and the release rates from V2O5 were r = 0.131·（[H＋]）--（0.104） at pH 3.1–10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium（Ⅲ, Ⅳ and Ⅴ） oxides（33.4–87.5 kJ/mol） were determined at pH 3.8, pH 6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose,albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment.
基金the financial support from the National Natural Science Foundation of China(No.51801078).
文摘To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were prepared by hydrothermal and subsequent heat treatment.The beginning hydrogen desorption temperature of 7 wt.%Ni_(3)V_(2)O_(8)-rGO modified MgH_(2)was reduced to 208℃,while the additive-free MgH_(2)and 7 wt.%Ni_(3)V_(2)O_(8)doped MgH_(2)appeared to discharge hydrogen at 340 and 226℃,respectively.A charging capacity of about 4.7 wt.%H_(2)for MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO was achieved at 125℃ in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215℃.The microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)N_(i)H_(4) and metallic V contributed significantly to the enhanced performance of MgH_(2).In addition,the presence of rGO in the MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO composite reduced particle aggregation tendency of Mg/MgH_(2),leading to improving the cyclic stability of MgH_(2)during 20 cycles.
