Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life p...Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life period of Crl2 steel as punching die. Kinetics of vanadium carbide coating growth was brought forward and verified by comparison of the mathematical model with the experimental results. The thickness of coating was illustrated by SEM. The chemical constituent of coating and remnants were tested by X-ray diffraction （XRD） and X-ray energy dispersive spectroscopy （EDS）. To increase the thickness, rare earth silicon powder （FeSiRe23） was added to the borax salt bath. The analysis of XRD revealed that FeSiRe23 increased the depth of vanadium car-bide coating as reducing agent and catalysis.展开更多
Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone d...Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone different periods of vanadizing time at 950 ℃ was measured. These depth values ( x ) and its corresponded time ( t ) were substituded into the experimental formula, i.e., x n=Kt (ln x=(1/n) ln K+(1/n) ln t ), and were processed by mono linear regression. It is found that x and t have the relationship of x 2=Kt . Addition of rare earth can promote reaction of the permeating agent, and increase vanadium potential of the agent. Rare earth, as a strong reductant, makes the oxide on the steel surface reduced, and thus activates the steel surface. Permeating of rare earth into steel and the VC layer intensifies the crystal fault density, and, together with its excellent chemical activation, makes carbon atoms diffuse easily. These functions of rare earth can decrease the diffusion activation energy of the carbon atoms, and therefore has catalytic effect on permeation.展开更多
Sodium-ion batteries(SIBs)hold great promise for large-scale energy storage in the post-lithium-ion battery era due to their high rate performance and long lifespan,although their sluggish Na^(+) transformation kineti...Sodium-ion batteries(SIBs)hold great promise for large-scale energy storage in the post-lithium-ion battery era due to their high rate performance and long lifespan,although their sluggish Na^(+) transformation kinetics still require improvement.Encouraged by the excellent electrochemical performance of titanium-based anode materials,here,we present a novel titanium vanadate@carbon(TVO@C)material as anode for SIBs.Our TVO@C material is synthesized via a facile coprecipitation method,with the following annealing process in an acetylene atomosphere.The opened ion channel and the oxygen vacancies within TVO@C facilitate the diffusion of Na^(+) ions,reducing their diffusion barrier.Thus,an ultrahigh rate of 100 A g^(-1)and long life of 10,000 cycles have been achieved.Furthermore,the TVO@C electrode exhibits stable performance,not only at room temperature,but also at temperatures as low as 20 C.The TVO@CjjNa_(3)V_(2)(PO_(4))_(3)@C full cells have also achieved stable discharge/charge for 500 cycles.It is believed that this strategy provides new insight into the development of advanced electrodes and provides a new opportunity for constructing novel high rate electrodes.展开更多
Developing fast-charging lithium-ion batteries(LIBs)that feature high energy density is critical for the scalable application of electric vehicles.Iron vanadate(FVO)holds great potential as anode material in fast-char...Developing fast-charging lithium-ion batteries(LIBs)that feature high energy density is critical for the scalable application of electric vehicles.Iron vanadate(FVO)holds great potential as anode material in fast-charging LIBs because of its high theoretical specific capacity and the high natural abundance of its constituents.However,the capacity of FVO rapidly decays due to its low electrical conductivity.Herein,uniform FVO nanoparticles are grown in situ on ordered mesoporous carbon(CMK-3)support,forming a highly electrically conductive porous network,FVO/CMK-3.The structure of CMK-3 helps prevent agglomeration of FVO particles.The electrically conductive nature of CMK-3 can further enhance the electrical conductivity of FVO/CMK-3 and buffer the volume expansion of FVO particles during cycling processes.As a result,the FVO/CMK-3 displays excellent fast-charging performance of 364.6 mAh·g^(-1)capacity for 2500 cycles at 10 A·g^(-1)(with an ultralow average capacity loss per cycle of 0.003%)through a pseudocapacitive-dominant process.Moreover,the LiCoO_(2)//FVO/CMK-3 full cell achieves a high capacity of 100.2 mAh·g^(-1)and a high capacity retention(96.2%)after 200 cycles.The superior electrochemical performance demonstrates that FVO/CMK-3 is an ideal anode material candidate for fast-charging,stable LIBs with high energy density.展开更多
Efficient removal of antibiotics is of great significance for the sustainability of aquatic ecosystems.In this work,a new polyoxometalate-based metal-organic hybrid material[Ag_(3)L_(0.5)(HSiW_(12)O_(4)0)]·2C_(2)...Efficient removal of antibiotics is of great significance for the sustainability of aquatic ecosystems.In this work,a new polyoxometalate-based metal-organic hybrid material[Ag_(3)L_(0.5)(HSiW_(12)O_(4)0)]·2C_(2)H_(5)OH·2CH_(3)CN(Ag-L-SiW_(12))was prepared by using Keggin-type polyoxometalate anion and thiacalix[4]arene-based ligand(L)via solvothermal method.Subsequently,a composite heterojunction Ag-L-SiW_(12)@BiVO_(4)photoanode was fabricated by loading Ag-L-SiW_(12)on the surface of BiVO_(4).The photoelectrocatalytic degradation performance of ciprofloxacin(CIP)was explored under the simulated solar radiation.Remarkably,the CIP degradation efficiency reached 93%within 240 min using the optimal Ag-LSiW_(12)@BiVO_(4)photoanode,which is approximately 2 and 23 times those of pristine BiVO_(4)and Ag-L-SiW_(12),respectively.Furthermore,density functional theory(DFT)calculations were conducted to elucidate the role of Ag-L-SiW_(12)during the photoelectrocatalytic process.This work offers an example of the efficient composite photoelectrocatalysts for the treatment of antibiotic wastewater.展开更多
A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vana...A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.展开更多
High-performance aqueous zinc(Zn)-ion batteries(AZIBs)have emerged as one of the greatest favorable candidates for next-generation energy storage systems because of their low cost,sustainability,high safety,and eco-fr...High-performance aqueous zinc(Zn)-ion batteries(AZIBs)have emerged as one of the greatest favorable candidates for next-generation energy storage systems because of their low cost,sustainability,high safety,and eco-friendliness.In this report,we prepared magnesium vanadate(MgVO)-based nanostructures by a facile single-step solvothermal method with varying experimental reaction times(1,3,and 6 h)and investigated the effect of the reaction time on the morphology and layered structure for MgVO-based compounds.The newly prepared MgVO-1 h,MgVO-3 h and MgVO-6 h samples were used as cathode materials for AZIBs.Compared to the MgVO-1 h and MgVO-6 h cathodes,the MgVO-3 h cathode showed a higher specific capacity of 492.74 mA h g^(-1) at 1 A g^(-1) over 500 cycles and excellent rate behavior(291.58 mA h g^(-1) at 3.75 A g^(-1))with high cycling stability(116%)over 2000 cycles at 5 A g^(-1).Moreover,the MgVO-3 h electrode exhibited good electrochemical performance owing to its fast Zn-ion diffusion kinetics.Additionally,various ex-situ analyses confirmed that the MgVO-3 h cathode displayed excellent insertion/extraction of Zn^(2+)ions during charge and discharge processes.This study offers an efficient method for the synthesis of nanostructured MgVO-based cathode materials for high-performance AZIBs.展开更多
Metal vanadates garner significant interest because of their exceptional potential for use in diverse practical applications,which stems from their unique framework structures,bond strength heterogeneities,and strong ...Metal vanadates garner significant interest because of their exceptional potential for use in diverse practical applications,which stems from their unique framework structures,bond strength heterogeneities,and strong O^(2-)-V^(5+)charge-transfer bands.However,their optoelectronic properties have not yet been sufficiently explored.In this study,we synthesized three high-purity calcium vanadate compounds(Ca V_(2)O_(6),Ca_(2)V_(2)O_(7),and Ca_(3)V_(2)O_(8))and comprehensively investigated their optoelectronic properties via first-principles calculations and experimental characterizations.Ca V_(2)O_(6),Ca_(2)V_(2)O_(7),and Ca_(3)V_(2)O_(8) are indirect band gap semiconductors with band gaps of 2.5-3.4 e V.A comparative analysis between density functional theory(DFT)and DFT+U(local Coulomb interaction,U)calculations revealed that standard DFT was sufficient to accurately describe the lattice parameters and band gaps of these vanadates.Further luminescence studies revealed significant photo-and electro-luminescence properties within the visible light spectrum.Notably,the luminescence intensity of CaV_(2)O_(6) exhibited a remarkable 10-fold enhancement under a modest pressure of only 0.88 GPa,underscoring its exceptional potential for use in pressure-tunable optical applications.These findings provide deeper insight into the electronic structures and optical behaviors of vanadates and highlight their potential as strong candidates for application in phosphor materials and optoelectronic devices.展开更多
In situ growth of co-catalysts on BiVO_(4)(BVO)to enhance photoelectrochemical(PEC)water splitting performance has been extensively reported.However,the understanding of the synergistic effects among various elements,...In situ growth of co-catalysts on BiVO_(4)(BVO)to enhance photoelectrochemical(PEC)water splitting performance has been extensively reported.However,the understanding of the synergistic effects among various elements,especially at the interface between the semiconductor and cocatalyst,has received insufficient attention.In this study,we report a Co,Ni and Mn trimetallic fluoride-modified BVO photoanode featuring a unique interfacial chemical bond(V-F).Under AM 1.5 G illumination,an exciting photocurrent density of 6.05 mA cm^(-2)was achieved at 1.23 V vs.RHE by the integrated BVO/CoNi_(0.18)Mn_(0.12)(OH)_(x)F photoanode and over 98%of the initial photocurrent was maintained after 10 h of photoelectrolysis.Control experiments and theoretical calculations demonstrate that the V-F interfacial bond stabilizes the Co^(2+)active sites.It serves as a transmission gear,interlinking the migration of interfacial charge and the regeneration of cocatalyst,endowing the photoanode with significant activity and stability.Furthermore,we have systematically elucidated the role of the individual Co,Ni,and Mn components in the synergistic cocatalyst layer.The interfacial modification provides novel insights into developing advanced photoanodes towards PEC water splitting.展开更多
Microbial vanadate(V(V))reduction is a key process for environmental geochemistry and detoxification of vanadium(V).However,the electron transfer pathways and V isotope fractionation involved in this process are not y...Microbial vanadate(V(V))reduction is a key process for environmental geochemistry and detoxification of vanadium(V).However,the electron transfer pathways and V isotope fractionation involved in this process are not yet fully understood.In this study,the V(V)reduction mechanisms with concomitant V isotope fractionation by the Gram-positive bacterium Bacillus subtilis(B.subtilis)and the Gramnegative bacterium Thauera humireducens(T.humireducens)were investigated.Both strains could effectively reduce V(V),removing(90.5%±1.6%)and(93.0%±1.8%)of V(V)respectively from an initial concentration of 50 mg L^(-1) during a 10-day incubation period.V(V)was bioreduced to insoluble vanadium(IV),which was distributed both inside and outside the cells.Electron transfer via cytochrome C,nicotinamide adenine dinucleotide,and glutathione played critical roles in V(V)reduction.Metabolomic analysis showed that differentially enriched metabolites(quinone,biotin,and riboflavin)mediated electron transfer in both strains.The aqueous V in the remaining solution became isotopically heavier as V(V)bioreduction proceeded.The obtained V isotope composition dynamics followed a Rayleigh fractionation model,and the isotope enrichment factor(e)was(–0.54‰±0.04‰)for B.subtilis and(–0.32‰±0.03‰)for T.humireducens,with an insignificant difference.This study provides molecular insights into electron transfer for V(V)bioreduction and reveals V isotope fractionation during this bioprocess,which is helpful for understanding V biogeochemistry and developing novel strategies for V remediation.展开更多
Layered ammonium vanadate has become a promising cathode material for aqueous zinc ion batteries(ZIBs)due to its small mass and large ionic radius of ammonium ions as well as the consequent large layer spacing and hig...Layered ammonium vanadate has become a promising cathode material for aqueous zinc ion batteries(ZIBs)due to its small mass and large ionic radius of ammonium ions as well as the consequent large layer spacing and high specific capacity.However,the irreversible de-ammoniation caused by N·H···O bonds damaged would impair cycle life of ZIBs and the strong electrostatic interaction between Zn^(2+)and V-O frame could slower the mobility of Zn^(2+).Furthermore,the thermal instability of ammonium vanadate also limits the use of common carbon coating modification method to solve the problem.Herein,V_(2)CT_(X)MXene was innovatively selected as a bifunctional source to in-situ derivatized(NH_(4))_(2)V_(8)O_(20)·x H_(2)O with amorphous carbon-coated(NHVO@C)via one-step hydrothermal method in relatively moderate temperature.The amorphous carbon shell derived from the V_(2)CT_(X)MXene as a conductive framework to effectively improve the diffusion kinetics of Zn^(2+)and the robust carbon skeleton could alleviate the ammonium dissolution during long-term cycling.As a result,zinc ion batteries using NHVO@C as cathode exhibit superior electrochemical performance.Moreover,the assembled foldable or high loading(10.2 mg/cm^(2))soft-packed ZIBs further demonstrates its practical application.This study provided new insights into the development of the carbon cladding process for thermally unstable materials in moderate temperatures.展开更多
Aqueous Zn-ion batteries have attracted much attention due to their unique high safety and low-cost merits.However,their practical applications are at a slow pace due to their short cycle life,which fundamentally resu...Aqueous Zn-ion batteries have attracted much attention due to their unique high safety and low-cost merits.However,their practical applications are at a slow pace due to their short cycle life,which fundamentally results from the instability of the positive/negative electrode interface in the traditional dilute aqueous electrolytes with high water activity.Developing highly concentrated electrolyte(HCE)has been considered as an effective solution.Unlike previous studies of single salt-based HCE(SSHCE),herein,a new dual-salt HCE(15 m ZnCl_(2)+10 m NH_(4)NH_(2)SO_(3)DS-HCE)was proposed for the first time.DS-HCE was proven to simultaneously possess higher conductivity than traditional dilute electrolytes and ultralow water activity of SS-HCE by the regulation of dual high-concentration salts on the solvation structure,which renders the Zn‖Zn symmetric cell the record-long cycling life of 2200 h compared with those with SS-HCE(30 m ZnCl_(2),300 h)and other reported HCEs.Additionally,the Zn‖NH_(4)V_(4)O_(10)full cell with DS-HCE demonstrated impressed rate capability within a wide-range current densities from 0.1 to 10 A g^(-1).Moreover,at the high current density of 5 A g^(-1),the full cell shows almost100%capacity retention after 4000 cycles,which indicates the promising future of the DS-HCE system for long-duration aqueous Zn-ion batteries.展开更多
LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity...LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity decay,and poor cycling performance in conventional lithium-ion battery cathode materials.The charge-discharge processes of LVO span multiple platforms,delivering an impressive specific discharge capacity of 219.4 mAh.g^(-1) at 1C.Remarkably,LVO exhibits a high-capacity retention rate of 81.3%after 800 cycles within the typical operating voltage range of lithium-ion batteries(2.8-4.3V).Rate capability tests and electrochemical impedance spectroscopy(EIS)reveal that,compared to traditional cathode materials,LVO significantly enhances Li*diffusion rates(D_(Li*))and reduces charge transfer resistance(Ret).展开更多
Photoelectrochemical(PEC)water splitting using bismuth vanadate(BiVO_(4))as a photoanode shows promise for renewable hydrogen production.Depositing cobalt phosphate(CoPi)on the BiVO_(4)photoanode as an oxygen evolutio...Photoelectrochemical(PEC)water splitting using bismuth vanadate(BiVO_(4))as a photoanode shows promise for renewable hydrogen production.Depositing cobalt phosphate(CoPi)on the BiVO_(4)photoanode as an oxygen evolution cocatalyst(OEC)is an effective method to improve the PEC performance.However,the CoPi/BiVO_(4)photoanode still faces challenges in terms of slow interface photogenerated carrier transport.Herein,we utilize the advantage of the classical strong metal-support interaction(SMSI)between Au and BiVO_(4)to prepare a CoPi/Au/BiVO_(4)(SMSI-CoPi/Au/BiVO_(4))photoanode.Due to the formation of SMSI,the accumulated electrons at the interface of CoPi/Au induce the accelerated extraction of photogenerated holes.Meanwhile,the active electron density of CoPi is increased,leading to improved water oxidation kinetic.As a result,the SMSI-CoPi/Au/BiVO_(4)photoanode exhibits a high photocurrent density of 5.01 m A cm^(-2)at 1.23 V versus the reversible hydrogen electrode and an applied bias photon-to-current efficiency of 1.78%.This work highlights a novel approach to enhance hole transfer and water oxidation kinetics of OEC/BiVO_(4)composite photoanodes,offering the great potential of using SMSI for PEC water splitting.展开更多
The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited ...The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited a high formate Faradaic efficiency(FE)of 97.45%(-0.9 V)and a large partial current density of-45.82 mA/cm^(2)(-1.2 V).The good performance benefits from the reconstruction of BiVO_(4)to generate active metal Bi sites,which results in the electron redistribution to boost the OCHO∗formation.In flow cells,near industrial current density of 183.94 mA/cm^(2)was achieved,with the FE of formate above 95%from 20mA/cm^(2)to 180mA/cm^(2).Our work provides a facily synthesized BiVO_(4)precatalyst for CO_(2)electroreduction.展开更多
Large-scale bismuth vanadate(BiVO_(4))photoanodes are critical to the practical application of photoelectrochemical water splitting devices.However,the lack of interface-modified coatings with simultaneous low cost,sc...Large-scale bismuth vanadate(BiVO_(4))photoanodes are critical to the practical application of photoelectrochemical water splitting devices.However,the lack of interface-modified coatings with simultaneous low cost,scalability,high hole transport efficiency,low impedance,and photocorrosion resistance is a major challenge that prevents the practical application of large-size photoanodes.Here,we present a scalable nickel-chelated polydopamine conformal coating for modifying BiVO_(4)(BiVO_(4)@PDA-Ni,BPNi),achieving over 500 h of stable water oxidation at 0.6 VRHE.The excellent stability is attributed to the chelated Ni acting as hole oxidation sites for PDA,thereby suppressing the accumulated-holes-induced PDA decomposition.Additionally,the in situ generation of Ni(IV)facilitates the structural reorganization of PDA in the photoelectrochemical system,further enhancing the stability of the PDA matrix.The findings of PDA photodegradation,its autonomous metal ion capture within photoelectrochemical systems,and the rapid deactivation of BPNi photoanodes caused by vanadium(V)ions have all provided significant guidance for the enhancement of PDA.Our study demonstrates that nickel-chelated polydopamine can be applied to large-scale BiVO_(4) photoanodes to facilitate oxygen evolution.This will promote the development of large-scale photoanodes suitable for photoelectrochemical devices.展开更多
The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_...The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_(x)VO_(4) nanoparticles were studied as a function of Ni content.The experimental results show that the prepared Ni-doped FeVO_(4) samples have a triclinic structure.Scanning electron microscopy(SEM)images reveal a decrease in average nanoparticle size with increasing Ni content,leading to an enhancement in both specific surface area and magnetization values.X-ray absorption near edge structure(XANES)analysis confirms the substitution of Ni^(2+)ions into Fe^(3+)sites.The magnetic investigation reveals that Ni-doped FeVO_(4) exhibits weak ferromagnetic behavior at room temperature,in contrast to the antiferromagnetic behavior observed in the undoped FeVO_(4).Electrochemical studies demonstrate that the Fe_(0.95)Ni_(0.05)VO_(4) electrode achieves the highest specific capacitance of 334.05 F·g^(−1) at a current density of 1 A·g^(−1),which is attributed to its smallest average pore diameter.In addition,the enhanced specific surface of the Fe_(0.8)Ni_(0.2)VO_(4) electrode is responsible for its outstanding cyclic stability.Overall,our results suggest that the magnetic and electrochemical properties of FeVO_(4) nanoparticles could be effectively tuned by varying Ni doping contents.展开更多
Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction ki...Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction kinetics and poor structural stability.In this study,we synthesized[Me_(2)NH_(2)]V_(3)O_(7)(MNVO),a layered vanadate with expended layer spacing and enhanced pH resistance,using a one-step simple hydrothermal gram-scale method.Experimental analyses and density functional theory(DFT)calculations revealed supportive ionic and hydrogen bonding interactions between the thin-layered[Me_(2)NH_(2)]+cation and[V_(3)O_(7)]-anion layers,clarifying the energy storage mechanism of the H^(+)/Zn^(2+)co-insertion.The synergistic effect of these bonds and oxygen vacancies increased the electronic conductivity and significantly reduced the diffusion energy barrier of the insertion ions,thereby improving the rate capability of the material.In an acidic electrolyte,aqueous zinc-ion batteries employing MNVO as the cathode exhibited a high specific capacity of 433 mAh g^(-1)at 0.1 A g^(-1).The prepared electrodes exhibited a maximum specific capacity of 237 mAh g^(-1)at 5 A g^(-1)and maintained a capacity retention of 83.5%after 10,000 cycles.This work introduces a novel approach for advancing layered cathodes,paving the way for their practical application in energy storage devices.展开更多
Elemental doping of BiVO_(4) crystal lattices effectively enhances carrier separation,thereby facilitating efficient photoelectrochemical water splitting.However,the positive effect of elementally induced lattice dist...Elemental doping of BiVO_(4) crystal lattices effectively enhances carrier separation,thereby facilitating efficient photoelectrochemical water splitting.However,the positive effect of elementally induced lattice distortions on hole extraction has been neglected.Herein,the crystal lattice of BiVO_(4) is distorted by doping with an inexpensive Cs metal;then,CoFe_(2)O_(4) is used as an efficient hole-extraction layer to further modify the surface of the doped photoanode.Benefiting from the above design,the newly prepared CoFe_(2)O_(4)-Cs-BiVO_(4) photoanode achieved a photocurrent density of 5.66 mA cm^(–2) at 1.23 V vs.a reversible hydrogen electrode,indicating a 3.9-fold improvement in photocurrent density.Detailed physicochemical characterization and density functional theory calculations showed that the lattice distortion induced by Cs doping promoted the directional migration of BiVO_(4) bulk-phase holes to the CoFe_(2)O_(4) layer.Additionally,the coupled CoFe_(2)O_(4) can be used as a hole extraction layer to further enhance the interfacial migration of carriers.The synergistic effect of the two effectively promotes the directional migration of photogenerated carriers from the BiVO_(4) bulk phase to the active sites of the oxygen evolution reaction,thereby effectively inhibiting carrier recombination.This study revealed the positive effect of the dual-hole extraction strategy on solar energy conversion,thereby opening new avenues for the rational design of photoanodes.展开更多
Vanadium-based cathode materials are attractive for aqueous zinc-ion batteries(AZIBs)owing to the high capacity from their open frameworks and multiple valences.However,the cycle stability and rate capability are stil...Vanadium-based cathode materials are attractive for aqueous zinc-ion batteries(AZIBs)owing to the high capacity from their open frameworks and multiple valences.However,the cycle stability and rate capability are still restricted by the low electrical conductivity and trapped diffusion kinetics.Here,we propose an organic-inorganic co-intercalation strategy to regulate the structure of ammonium vanadate(NH_(4)V_(4)O_(10),NVO).The introduction of Al^(3+)and polyaniline(PANI)induces the optimized layered structure and generation of urchin-like hierarchical construction(AP-NVO),based on heterogeneous nucleation and dissolution-recrystallization growth mechanism.Owing to these favorable features,the AP-NVO electrode delivers a desirable discharge capacity of 386 mA h g^(-1) at 1.0 A g^(-1),high-rate capability of 263 mA h g^(-1 )at 5.0 A g^(-1) and excellent cycling stability with 80.4%capacity retention over 2000 cycles at 5.0 A g^(-1).Such satisfactory electrochemical performance is believed to result from the enhanced reaction kinetics provided by the stable layered structure and a high intercalation pseudo-capacitance reaction.These results could provide enlightening insights into the design of layered vanadium oxide cathodematerials.展开更多
基金Funded by the National Natural Science Foundation of China (No.50675165)the National Key Technology R&D Program (No.2006BAF02A29)
文摘Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life period of Crl2 steel as punching die. Kinetics of vanadium carbide coating growth was brought forward and verified by comparison of the mathematical model with the experimental results. The thickness of coating was illustrated by SEM. The chemical constituent of coating and remnants were tested by X-ray diffraction （XRD） and X-ray energy dispersive spectroscopy （EDS）. To increase the thickness, rare earth silicon powder （FeSiRe23） was added to the borax salt bath. The analysis of XRD revealed that FeSiRe23 increased the depth of vanadium car-bide coating as reducing agent and catalysis.
文摘Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone different periods of vanadizing time at 950 ℃ was measured. These depth values ( x ) and its corresponded time ( t ) were substituded into the experimental formula, i.e., x n=Kt (ln x=(1/n) ln K+(1/n) ln t ), and were processed by mono linear regression. It is found that x and t have the relationship of x 2=Kt . Addition of rare earth can promote reaction of the permeating agent, and increase vanadium potential of the agent. Rare earth, as a strong reductant, makes the oxide on the steel surface reduced, and thus activates the steel surface. Permeating of rare earth into steel and the VC layer intensifies the crystal fault density, and, together with its excellent chemical activation, makes carbon atoms diffuse easily. These functions of rare earth can decrease the diffusion activation energy of the carbon atoms, and therefore has catalytic effect on permeation.
基金supported by National Nature Science Foundation of China(22105118)Nature Science Foundation of Shandong Provinces(ZR2021QB095)China Postdoctoral Science Foundation(2020TQ0183 and 2021M701979).
文摘Sodium-ion batteries(SIBs)hold great promise for large-scale energy storage in the post-lithium-ion battery era due to their high rate performance and long lifespan,although their sluggish Na^(+) transformation kinetics still require improvement.Encouraged by the excellent electrochemical performance of titanium-based anode materials,here,we present a novel titanium vanadate@carbon(TVO@C)material as anode for SIBs.Our TVO@C material is synthesized via a facile coprecipitation method,with the following annealing process in an acetylene atomosphere.The opened ion channel and the oxygen vacancies within TVO@C facilitate the diffusion of Na^(+) ions,reducing their diffusion barrier.Thus,an ultrahigh rate of 100 A g^(-1)and long life of 10,000 cycles have been achieved.Furthermore,the TVO@C electrode exhibits stable performance,not only at room temperature,but also at temperatures as low as 20 C.The TVO@CjjNa_(3)V_(2)(PO_(4))_(3)@C full cells have also achieved stable discharge/charge for 500 cycles.It is believed that this strategy provides new insight into the development of advanced electrodes and provides a new opportunity for constructing novel high rate electrodes.
基金supported by the National Natural Science Foundation of China(No.52002170)the Central Guidance Fund Project for Local Scientific and Technological Development in Qinghai Province(No.2024ZY013)+1 种基金the Foundation of Key Laboratory of Flexible Electronics of Zhejiang Province(No.2023FE011)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_1635).
文摘Developing fast-charging lithium-ion batteries(LIBs)that feature high energy density is critical for the scalable application of electric vehicles.Iron vanadate(FVO)holds great potential as anode material in fast-charging LIBs because of its high theoretical specific capacity and the high natural abundance of its constituents.However,the capacity of FVO rapidly decays due to its low electrical conductivity.Herein,uniform FVO nanoparticles are grown in situ on ordered mesoporous carbon(CMK-3)support,forming a highly electrically conductive porous network,FVO/CMK-3.The structure of CMK-3 helps prevent agglomeration of FVO particles.The electrically conductive nature of CMK-3 can further enhance the electrical conductivity of FVO/CMK-3 and buffer the volume expansion of FVO particles during cycling processes.As a result,the FVO/CMK-3 displays excellent fast-charging performance of 364.6 mAh·g^(-1)capacity for 2500 cycles at 10 A·g^(-1)(with an ultralow average capacity loss per cycle of 0.003%)through a pseudocapacitive-dominant process.Moreover,the LiCoO_(2)//FVO/CMK-3 full cell achieves a high capacity of 100.2 mAh·g^(-1)and a high capacity retention(96.2%)after 200 cycles.The superior electrochemical performance demonstrates that FVO/CMK-3 is an ideal anode material candidate for fast-charging,stable LIBs with high energy density.
基金supported by the National Natural Science Foundation of China(Grant No.21471029).
文摘Efficient removal of antibiotics is of great significance for the sustainability of aquatic ecosystems.In this work,a new polyoxometalate-based metal-organic hybrid material[Ag_(3)L_(0.5)(HSiW_(12)O_(4)0)]·2C_(2)H_(5)OH·2CH_(3)CN(Ag-L-SiW_(12))was prepared by using Keggin-type polyoxometalate anion and thiacalix[4]arene-based ligand(L)via solvothermal method.Subsequently,a composite heterojunction Ag-L-SiW_(12)@BiVO_(4)photoanode was fabricated by loading Ag-L-SiW_(12)on the surface of BiVO_(4).The photoelectrocatalytic degradation performance of ciprofloxacin(CIP)was explored under the simulated solar radiation.Remarkably,the CIP degradation efficiency reached 93%within 240 min using the optimal Ag-LSiW_(12)@BiVO_(4)photoanode,which is approximately 2 and 23 times those of pristine BiVO_(4)and Ag-L-SiW_(12),respectively.Furthermore,density functional theory(DFT)calculations were conducted to elucidate the role of Ag-L-SiW_(12)during the photoelectrocatalytic process.This work offers an example of the efficient composite photoelectrocatalysts for the treatment of antibiotic wastewater.
基金finally supported by the National Natural Science Foundation of China (Nos.52204309,52174277,52374300)。
文摘A simplified CaO-V_(2)O_(5)-MnO_(2) system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates.The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V_(2)O_(5))/n(MnO_(2))ratios and roasting temperatures varied.When MnO_(2) was incrementally added with n(CaO)/n(V_(2)O_(5))of 2,some Ca_(2)V_(2)O_(7) converted to Mn_(2)V_(2)O_(7).The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate.Conversely,when CaO was gradually added with n(MnO_(2))/n(V_(2)O_(5))of 2,Mn_(2)V_(2)O_(7) tended to transform into Ca_(2)V_(2)O_(7) and Ca3V2O8.The affinity of vanadium for calcium was higher compared that of vanadium for manganese.The specific type of calcium vanadate formed depended on both n(CaO)/n(V_(2)O_(5))/n(MnO_(2))values and roasting temperatures,while manganese vanadate remained predominantly as Mn_(2)V_(2)O_(7).The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal.At n(CaO)/n(V_(2)O_(5))/n(MnO_(2))of 2/1/2 and temperatures ranging from 650 to 850°C,the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2018R1A6A1A03025708).
文摘High-performance aqueous zinc(Zn)-ion batteries(AZIBs)have emerged as one of the greatest favorable candidates for next-generation energy storage systems because of their low cost,sustainability,high safety,and eco-friendliness.In this report,we prepared magnesium vanadate(MgVO)-based nanostructures by a facile single-step solvothermal method with varying experimental reaction times(1,3,and 6 h)and investigated the effect of the reaction time on the morphology and layered structure for MgVO-based compounds.The newly prepared MgVO-1 h,MgVO-3 h and MgVO-6 h samples were used as cathode materials for AZIBs.Compared to the MgVO-1 h and MgVO-6 h cathodes,the MgVO-3 h cathode showed a higher specific capacity of 492.74 mA h g^(-1) at 1 A g^(-1) over 500 cycles and excellent rate behavior(291.58 mA h g^(-1) at 3.75 A g^(-1))with high cycling stability(116%)over 2000 cycles at 5 A g^(-1).Moreover,the MgVO-3 h electrode exhibited good electrochemical performance owing to its fast Zn-ion diffusion kinetics.Additionally,various ex-situ analyses confirmed that the MgVO-3 h cathode displayed excellent insertion/extraction of Zn^(2+)ions during charge and discharge processes.This study offers an efficient method for the synthesis of nanostructured MgVO-based cathode materials for high-performance AZIBs.
基金supported by the National Natural Science Foundation of China(Nos.12404045 and 52371148)the National Key R&D Program of China(No.2018YFC 1900500)+1 种基金the Foundation of Chongqing Normal University,China(No.23XLB015)the Science and Technology Research Program of Chongqing Municipal Education Commission,China(No.KJQN-202400553)。
文摘Metal vanadates garner significant interest because of their exceptional potential for use in diverse practical applications,which stems from their unique framework structures,bond strength heterogeneities,and strong O^(2-)-V^(5+)charge-transfer bands.However,their optoelectronic properties have not yet been sufficiently explored.In this study,we synthesized three high-purity calcium vanadate compounds(Ca V_(2)O_(6),Ca_(2)V_(2)O_(7),and Ca_(3)V_(2)O_(8))and comprehensively investigated their optoelectronic properties via first-principles calculations and experimental characterizations.Ca V_(2)O_(6),Ca_(2)V_(2)O_(7),and Ca_(3)V_(2)O_(8) are indirect band gap semiconductors with band gaps of 2.5-3.4 e V.A comparative analysis between density functional theory(DFT)and DFT+U(local Coulomb interaction,U)calculations revealed that standard DFT was sufficient to accurately describe the lattice parameters and band gaps of these vanadates.Further luminescence studies revealed significant photo-and electro-luminescence properties within the visible light spectrum.Notably,the luminescence intensity of CaV_(2)O_(6) exhibited a remarkable 10-fold enhancement under a modest pressure of only 0.88 GPa,underscoring its exceptional potential for use in pressure-tunable optical applications.These findings provide deeper insight into the electronic structures and optical behaviors of vanadates and highlight their potential as strong candidates for application in phosphor materials and optoelectronic devices.
文摘In situ growth of co-catalysts on BiVO_(4)(BVO)to enhance photoelectrochemical(PEC)water splitting performance has been extensively reported.However,the understanding of the synergistic effects among various elements,especially at the interface between the semiconductor and cocatalyst,has received insufficient attention.In this study,we report a Co,Ni and Mn trimetallic fluoride-modified BVO photoanode featuring a unique interfacial chemical bond(V-F).Under AM 1.5 G illumination,an exciting photocurrent density of 6.05 mA cm^(-2)was achieved at 1.23 V vs.RHE by the integrated BVO/CoNi_(0.18)Mn_(0.12)(OH)_(x)F photoanode and over 98%of the initial photocurrent was maintained after 10 h of photoelectrolysis.Control experiments and theoretical calculations demonstrate that the V-F interfacial bond stabilizes the Co^(2+)active sites.It serves as a transmission gear,interlinking the migration of interfacial charge and the regeneration of cocatalyst,endowing the photoanode with significant activity and stability.Furthermore,we have systematically elucidated the role of the individual Co,Ni,and Mn components in the synergistic cocatalyst layer.The interfacial modification provides novel insights into developing advanced photoanodes towards PEC water splitting.
基金supported by the National Natural Science Foundation of China(U21A2033)the Fundamental Research Funds for the Central Universities(2652022103).
文摘Microbial vanadate(V(V))reduction is a key process for environmental geochemistry and detoxification of vanadium(V).However,the electron transfer pathways and V isotope fractionation involved in this process are not yet fully understood.In this study,the V(V)reduction mechanisms with concomitant V isotope fractionation by the Gram-positive bacterium Bacillus subtilis(B.subtilis)and the Gramnegative bacterium Thauera humireducens(T.humireducens)were investigated.Both strains could effectively reduce V(V),removing(90.5%±1.6%)and(93.0%±1.8%)of V(V)respectively from an initial concentration of 50 mg L^(-1) during a 10-day incubation period.V(V)was bioreduced to insoluble vanadium(IV),which was distributed both inside and outside the cells.Electron transfer via cytochrome C,nicotinamide adenine dinucleotide,and glutathione played critical roles in V(V)reduction.Metabolomic analysis showed that differentially enriched metabolites(quinone,biotin,and riboflavin)mediated electron transfer in both strains.The aqueous V in the remaining solution became isotopically heavier as V(V)bioreduction proceeded.The obtained V isotope composition dynamics followed a Rayleigh fractionation model,and the isotope enrichment factor(e)was(–0.54‰±0.04‰)for B.subtilis and(–0.32‰±0.03‰)for T.humireducens,with an insignificant difference.This study provides molecular insights into electron transfer for V(V)bioreduction and reveals V isotope fractionation during this bioprocess,which is helpful for understanding V biogeochemistry and developing novel strategies for V remediation.
基金financially supported by the National Natural Science Foundation of China(Nos.52402271,22005167 and52302273)the Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province(No.2024KJH129)+2 种基金the Taishan Scholar Project of Shandong Provinceof China(Nos.tsqn202211160,tsqn202312199)Shandong Provincial Natural Science Foundation of China(Nos.ZR2022QE003 and ZR2023QE176)China Postdoctoral Science Foundation(No.2023M741810)。
文摘Layered ammonium vanadate has become a promising cathode material for aqueous zinc ion batteries(ZIBs)due to its small mass and large ionic radius of ammonium ions as well as the consequent large layer spacing and high specific capacity.However,the irreversible de-ammoniation caused by N·H···O bonds damaged would impair cycle life of ZIBs and the strong electrostatic interaction between Zn^(2+)and V-O frame could slower the mobility of Zn^(2+).Furthermore,the thermal instability of ammonium vanadate also limits the use of common carbon coating modification method to solve the problem.Herein,V_(2)CT_(X)MXene was innovatively selected as a bifunctional source to in-situ derivatized(NH_(4))_(2)V_(8)O_(20)·x H_(2)O with amorphous carbon-coated(NHVO@C)via one-step hydrothermal method in relatively moderate temperature.The amorphous carbon shell derived from the V_(2)CT_(X)MXene as a conductive framework to effectively improve the diffusion kinetics of Zn^(2+)and the robust carbon skeleton could alleviate the ammonium dissolution during long-term cycling.As a result,zinc ion batteries using NHVO@C as cathode exhibit superior electrochemical performance.Moreover,the assembled foldable or high loading(10.2 mg/cm^(2))soft-packed ZIBs further demonstrates its practical application.This study provided new insights into the development of the carbon cladding process for thermally unstable materials in moderate temperatures.
基金financially supported by the National Natural Science Foundation of China(Grant No.52171147)the Tenthousand Talents Program+2 种基金the K.C.Wong Pioneer Talent Programthe National Key R&D Program of China(2024YFE0101100)the Inner Mengolia Science and Technology Plan(No.2021ZD0033).
文摘Aqueous Zn-ion batteries have attracted much attention due to their unique high safety and low-cost merits.However,their practical applications are at a slow pace due to their short cycle life,which fundamentally results from the instability of the positive/negative electrode interface in the traditional dilute aqueous electrolytes with high water activity.Developing highly concentrated electrolyte(HCE)has been considered as an effective solution.Unlike previous studies of single salt-based HCE(SSHCE),herein,a new dual-salt HCE(15 m ZnCl_(2)+10 m NH_(4)NH_(2)SO_(3)DS-HCE)was proposed for the first time.DS-HCE was proven to simultaneously possess higher conductivity than traditional dilute electrolytes and ultralow water activity of SS-HCE by the regulation of dual high-concentration salts on the solvation structure,which renders the Zn‖Zn symmetric cell the record-long cycling life of 2200 h compared with those with SS-HCE(30 m ZnCl_(2),300 h)and other reported HCEs.Additionally,the Zn‖NH_(4)V_(4)O_(10)full cell with DS-HCE demonstrated impressed rate capability within a wide-range current densities from 0.1 to 10 A g^(-1).Moreover,at the high current density of 5 A g^(-1),the full cell shows almost100%capacity retention after 4000 cycles,which indicates the promising future of the DS-HCE system for long-duration aqueous Zn-ion batteries.
基金supported by the National Natural Science Foundation of China(Nos.52125405 and U22A20108)Thailand Science Research and Innovation Fund Chulalongkorn University,National Research Council of Thailand(NRCT)+1 种基金Chulalongkorn University(No.42A660383)the Hub of Talents:Sustainable Materials for Circular Economy,National Research Council of Thailand(NRCT).
文摘LithiumvanadatesLiV_(3)O_(8)-LiV_(6)O_(15)(LVO)witha heterojunction structure are synthesized using a conventional high-temperature solid-state method to address the challenges of low ionic conductivity,rapid capacity decay,and poor cycling performance in conventional lithium-ion battery cathode materials.The charge-discharge processes of LVO span multiple platforms,delivering an impressive specific discharge capacity of 219.4 mAh.g^(-1) at 1C.Remarkably,LVO exhibits a high-capacity retention rate of 81.3%after 800 cycles within the typical operating voltage range of lithium-ion batteries(2.8-4.3V).Rate capability tests and electrochemical impedance spectroscopy(EIS)reveal that,compared to traditional cathode materials,LVO significantly enhances Li*diffusion rates(D_(Li*))and reduces charge transfer resistance(Ret).
基金supported by the National Natural Science Foundation of China(Nos.52472241,52403108 and 52301285)Department of Science and Technology of Hubei Province(Nos.2025AFA114 and 2024CSA076)+1 种基金Wuhan Science and Technology Bureau(Nos.2023020201010116 and 2024040801020319)Hubei Provincial Department of Education(No.Q20231703)。
文摘Photoelectrochemical(PEC)water splitting using bismuth vanadate(BiVO_(4))as a photoanode shows promise for renewable hydrogen production.Depositing cobalt phosphate(CoPi)on the BiVO_(4)photoanode as an oxygen evolution cocatalyst(OEC)is an effective method to improve the PEC performance.However,the CoPi/BiVO_(4)photoanode still faces challenges in terms of slow interface photogenerated carrier transport.Herein,we utilize the advantage of the classical strong metal-support interaction(SMSI)between Au and BiVO_(4)to prepare a CoPi/Au/BiVO_(4)(SMSI-CoPi/Au/BiVO_(4))photoanode.Due to the formation of SMSI,the accumulated electrons at the interface of CoPi/Au induce the accelerated extraction of photogenerated holes.Meanwhile,the active electron density of CoPi is increased,leading to improved water oxidation kinetic.As a result,the SMSI-CoPi/Au/BiVO_(4)photoanode exhibits a high photocurrent density of 5.01 m A cm^(-2)at 1.23 V versus the reversible hydrogen electrode and an applied bias photon-to-current efficiency of 1.78%.This work highlights a novel approach to enhance hole transfer and water oxidation kinetics of OEC/BiVO_(4)composite photoanodes,offering the great potential of using SMSI for PEC water splitting.
基金financially supported by the Fundamental Research Funds for the Central Universities of Central South University(No.2022ZZTS0579).
文摘The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited a high formate Faradaic efficiency(FE)of 97.45%(-0.9 V)and a large partial current density of-45.82 mA/cm^(2)(-1.2 V).The good performance benefits from the reconstruction of BiVO_(4)to generate active metal Bi sites,which results in the electron redistribution to boost the OCHO∗formation.In flow cells,near industrial current density of 183.94 mA/cm^(2)was achieved,with the FE of formate above 95%from 20mA/cm^(2)to 180mA/cm^(2).Our work provides a facily synthesized BiVO_(4)precatalyst for CO_(2)electroreduction.
基金support by National Natural Science Foundation of China(NSFC,Grant No.22379153 and 22109128)Ningbo Science And Technology Bureau:Ningbo Key Research and Development Project(2023Z147)Ningbo 3315 Program(2018A-13-C).
文摘Large-scale bismuth vanadate(BiVO_(4))photoanodes are critical to the practical application of photoelectrochemical water splitting devices.However,the lack of interface-modified coatings with simultaneous low cost,scalability,high hole transport efficiency,low impedance,and photocorrosion resistance is a major challenge that prevents the practical application of large-size photoanodes.Here,we present a scalable nickel-chelated polydopamine conformal coating for modifying BiVO_(4)(BiVO_(4)@PDA-Ni,BPNi),achieving over 500 h of stable water oxidation at 0.6 VRHE.The excellent stability is attributed to the chelated Ni acting as hole oxidation sites for PDA,thereby suppressing the accumulated-holes-induced PDA decomposition.Additionally,the in situ generation of Ni(IV)facilitates the structural reorganization of PDA in the photoelectrochemical system,further enhancing the stability of the PDA matrix.The findings of PDA photodegradation,its autonomous metal ion capture within photoelectrochemical systems,and the rapid deactivation of BPNi photoanodes caused by vanadium(V)ions have all provided significant guidance for the enhancement of PDA.Our study demonstrates that nickel-chelated polydopamine can be applied to large-scale BiVO_(4) photoanodes to facilitate oxygen evolution.This will promote the development of large-scale photoanodes suitable for photoelectrochemical devices.
文摘The Fe_(1−x)Ni_(x)VO_(4)(x=0,0.05,0.10,and 0.20)nanoparticles in this work were successfully synthesized via a co-precipitation method.The structural,magnetic and electrochemical properties of the prepared Fe_(1−x)Ni_(x)VO_(4) nanoparticles were studied as a function of Ni content.The experimental results show that the prepared Ni-doped FeVO_(4) samples have a triclinic structure.Scanning electron microscopy(SEM)images reveal a decrease in average nanoparticle size with increasing Ni content,leading to an enhancement in both specific surface area and magnetization values.X-ray absorption near edge structure(XANES)analysis confirms the substitution of Ni^(2+)ions into Fe^(3+)sites.The magnetic investigation reveals that Ni-doped FeVO_(4) exhibits weak ferromagnetic behavior at room temperature,in contrast to the antiferromagnetic behavior observed in the undoped FeVO_(4).Electrochemical studies demonstrate that the Fe_(0.95)Ni_(0.05)VO_(4) electrode achieves the highest specific capacitance of 334.05 F·g^(−1) at a current density of 1 A·g^(−1),which is attributed to its smallest average pore diameter.In addition,the enhanced specific surface of the Fe_(0.8)Ni_(0.2)VO_(4) electrode is responsible for its outstanding cyclic stability.Overall,our results suggest that the magnetic and electrochemical properties of FeVO_(4) nanoparticles could be effectively tuned by varying Ni doping contents.
基金Science Fund for Outstanding Young Scholars of Hunan Province,Grant/Award Number:2023JJ20064National Natural Science Foundation of China,Grant/Award Number:12004057+1 种基金Graduate Research and Innovation Foundation of Chongqing,Grant/Award Number:CYB23026Natural Science Foundation of Chongqing Municipality,Grant/Award Number:CSTB2022NSCQ-MSX1183。
文摘Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction kinetics and poor structural stability.In this study,we synthesized[Me_(2)NH_(2)]V_(3)O_(7)(MNVO),a layered vanadate with expended layer spacing and enhanced pH resistance,using a one-step simple hydrothermal gram-scale method.Experimental analyses and density functional theory(DFT)calculations revealed supportive ionic and hydrogen bonding interactions between the thin-layered[Me_(2)NH_(2)]+cation and[V_(3)O_(7)]-anion layers,clarifying the energy storage mechanism of the H^(+)/Zn^(2+)co-insertion.The synergistic effect of these bonds and oxygen vacancies increased the electronic conductivity and significantly reduced the diffusion energy barrier of the insertion ions,thereby improving the rate capability of the material.In an acidic electrolyte,aqueous zinc-ion batteries employing MNVO as the cathode exhibited a high specific capacity of 433 mAh g^(-1)at 0.1 A g^(-1).The prepared electrodes exhibited a maximum specific capacity of 237 mAh g^(-1)at 5 A g^(-1)and maintained a capacity retention of 83.5%after 10,000 cycles.This work introduces a novel approach for advancing layered cathodes,paving the way for their practical application in energy storage devices.
文摘Elemental doping of BiVO_(4) crystal lattices effectively enhances carrier separation,thereby facilitating efficient photoelectrochemical water splitting.However,the positive effect of elementally induced lattice distortions on hole extraction has been neglected.Herein,the crystal lattice of BiVO_(4) is distorted by doping with an inexpensive Cs metal;then,CoFe_(2)O_(4) is used as an efficient hole-extraction layer to further modify the surface of the doped photoanode.Benefiting from the above design,the newly prepared CoFe_(2)O_(4)-Cs-BiVO_(4) photoanode achieved a photocurrent density of 5.66 mA cm^(–2) at 1.23 V vs.a reversible hydrogen electrode,indicating a 3.9-fold improvement in photocurrent density.Detailed physicochemical characterization and density functional theory calculations showed that the lattice distortion induced by Cs doping promoted the directional migration of BiVO_(4) bulk-phase holes to the CoFe_(2)O_(4) layer.Additionally,the coupled CoFe_(2)O_(4) can be used as a hole extraction layer to further enhance the interfacial migration of carriers.The synergistic effect of the two effectively promotes the directional migration of photogenerated carriers from the BiVO_(4) bulk phase to the active sites of the oxygen evolution reaction,thereby effectively inhibiting carrier recombination.This study revealed the positive effect of the dual-hole extraction strategy on solar energy conversion,thereby opening new avenues for the rational design of photoanodes.
基金financially supported by the National Natural Science Foundation of China(U21A2077)the Taishan Scholar Project Foundation of Shandong Province(ts20190908)the Natural Science Foundation of Shandong Province(ZR2022MB084 and ZR2021ZD05).
文摘Vanadium-based cathode materials are attractive for aqueous zinc-ion batteries(AZIBs)owing to the high capacity from their open frameworks and multiple valences.However,the cycle stability and rate capability are still restricted by the low electrical conductivity and trapped diffusion kinetics.Here,we propose an organic-inorganic co-intercalation strategy to regulate the structure of ammonium vanadate(NH_(4)V_(4)O_(10),NVO).The introduction of Al^(3+)and polyaniline(PANI)induces the optimized layered structure and generation of urchin-like hierarchical construction(AP-NVO),based on heterogeneous nucleation and dissolution-recrystallization growth mechanism.Owing to these favorable features,the AP-NVO electrode delivers a desirable discharge capacity of 386 mA h g^(-1) at 1.0 A g^(-1),high-rate capability of 263 mA h g^(-1 )at 5.0 A g^(-1) and excellent cycling stability with 80.4%capacity retention over 2000 cycles at 5.0 A g^(-1).Such satisfactory electrochemical performance is believed to result from the enhanced reaction kinetics provided by the stable layered structure and a high intercalation pseudo-capacitance reaction.These results could provide enlightening insights into the design of layered vanadium oxide cathodematerials.
