MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery

The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.

Revealing the role of calcium ion intercalation of hydrated vanadium oxides for aqueous zinc-ion batteries

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.

Weakly Polarized Organic Cation-Modified Hydrated Vanadium Oxides for High-Energy Efficiency Aqueous Zinc-Ion Batteries

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.

Research progress on vanadium oxides for potassium-ion batteries

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.

Cs-Induced Phase Transformation of Vanadium Oxide for High-Performance Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries are promising candidate for gridscale energy storage.However,the development of zinc-ion batteries has been plagued by the lack of cathode materials with high specific capacity and superior lifespan.Herein,hexagonal Cs_(0.3)V_(2)O_(5)cathode is fabricated and investigated in zinc-ion batteries.Compared with the traditional vanadium oxides,the introduction of Cs changes the periodic atomic arrangements,which not only stabilizes the open framework structure but also facilitates the Zn^(2+)diffusion with a lower migration energy barrier.Consequently,high specific capacity of 543.8 mA h g^(-1)at 0.1 A g^(-1)is achieved,which surpasses most of reported cathode materials in zinc-ion batteries.The excellent cycle life is achieved over 1000 cycles with about 87.8%capacity retention at 2 A g^(-1).Furthermore,the morphological evolution and energy storage mechanisms are also revealed via a series of techniques.This work opens up a phase engineering strategy to fabricate the hexagonal vanadium oxide and elucidate the application of phase-dependent cathodes in zinc-ion batteries.

Competitive Redox Chemistries in Vanadium Niobium Oxide for Ultrafast and Durable Lithium Storage

Niobium pentoxide(Nb_(2)O_(5))anodes have gained increasing attentions for high-power lithium-ion batteries owing to the outstanding rate capability and high safety.However,Nb2O5 anode suffers poor cycle stability even after modified and the unrevealed mechanisms have restricted the practical applications.Herein,the over-reduction of Nb5+has been demonstrated to be the critical reason for the capacity loss for the first time.Besides,an effective competitive redox strategy has been developed to solve the rapid capacity decay of Nb_(2)O_(5),which can be achieved by the incorporation of vanadium to form a new rutile VNbO_(4)anode.The highly reversible V^(3+)/V^(2+)redox couple in VNbO_(4)can effectively inhibit the over-reduction of Nb^(5+).Besides,the electron migration from V^(3+)to Nb5+can greatly increase the intrinsic electronic conductivity for VNbO4.As a result,VNbO4 anode delivers a high capacity of 206.1 mAh g^(−1)at 0.1 A g^(−1),as well as remarkable cycle performance with a retention of 93.4%after 2000 cycles at 1.0 A g^(−1).In addition,the assembled lithium-ion capacitor demonstrates a high energy density of 44 Wh kg^(−1)at 5.8 kW kg^(−1).In summary,our work provides a new insight into the design of ultra-fast and durable anodes.

Methylene blue intercalated vanadium oxide with synergistic energy storage mechanism for highly efficient aqueous zinc ion batteries

With the rise of aqueous multivalent rechargeable batteries,inorganic-organic hybrid cathodes have attracted more and more attention due to the complement of each other’s advantages.Herein,a strategy of designing hybrid cathode is adopted for high efficient aqueous zinc-ion batteries(AZIBs).Methylene blue(MB)intercalated vanadium oxide(HVO-MB)was synthesized through sol-gel and ion exchange method.Compared with other organic-inorganic intercalation cathode,not only can the MB intercalation enlarge the HVO interlayer spacing to improve ion mobility,but also provide coordination reactions with the Zn^(2+)to enhance the intrinsic electrochemical reaction kinetics of the hybrid electrode.As a key component for the cathode of AZIBs,HVO-MB contributes a specific capacity of 418 mA h g^(-1) at 0.1 A g^(-1),high rate capability(243 mA h g^(-1) at 5 A g^(-1))and extraordinary stability(88%of capacity retention after 2000cycles at a high current density of 5 A g^(-1))in 3 M Zn(CF_(3)SO_(3))_(2) aqueous electrolyte.The electrochemical kinetics reveals HVO-MB characterized with large pseudocapacitance charge storage behavior due to the fast ion migration provided by the coordination reaction and expanded interlayer distance.Furthermore,a mixed energy storage mechanism involving Zn^(2+)insertion and coordination reaction is confirmed by various ex-situ characterization.Thus,this work opens up a new path for constructing the high performance cathode of AZIBs through organic-inorganic hybridization.

ZnO/V_(2)C/Fe_(2)O_(3)三元复合材料的制备及其对MB的光降解性能

采用高效催化剂技术可以处理工业废水中的污染物,而单相催化剂存在可见光响应范围窄的问题。通过静电自组装的方法制备ZnO/V_(2)C/Fe_(2)O_(3)三元光催化复合材料,利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等分析技术对复合材料进行表征,并以亚甲基蓝(MB)染料为目标污染物,研究三元复合物的光催化性能。在紫外光和可见光分别照射120 min后,ZnO/V_(2)C/Fe_(2)O_(3)三元复合材料对MB染料的降解速率分别是纯ZnO的19.68倍和21.76倍。在复合Fe_(2)O_(3)和V_(2)C后,缩短了ZnO禁带宽度,激发响应范围到可见光区域,有更大的比表面积和更多的反应活性位点,从而使ZnO的光催化性能增强。

Preparation and characterization of vanadium(IV) oxide supported on SBA-15 and its catalytic performance in benzene hydroxylation to phenol using molecular oxygen

Preparation of dispersed transition metal oxides catalyst with low oxidation state still remains a challenging task in heterogeneous catalysis.In this study,vanadium oxides supported on zeolite SBA-15 have been prepared under hydrothermal condition using V 2 O 5 and oxalic acid as sources of vanadium and reductant,respectively.The structures of samples,especially the oxidation state of vanadium,and the surface distribution of vanadium oxide species,have been thoroughly characterized using various techniques,including N 2-physisorption,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,UV-visible spectra（UV-Vis） and UV-visible-near infrared spectra（UV-Vis-NIR）.It is found that the majority of supported vanadium was in the form of vanadium（IV） oxide species with the low valence of vanadium.By adjusting hydrothermal treatment time,the surface distribution of vanadium（IV） oxide species can be tuned from vanadium（IV） oxide cluster to crystallites.These materials have been tested in the hydroxylation of benzene to phenol in liquid-phase with molecular oxygen in the absence of reductant.The catalyst exhibits high selectivity for phenol（61%） at benzene conversion of 4.6%,which is a relatively good result in comparison with other studies employing molecular oxygen as the oxidant.

Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering

This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were characterized with several different techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and Raman, when they were fresh from sputter chamber and aged after years, respectively, in order to determine their structure and composition. It finds that a small amount of sodium occurred on the surface of vanadium dioxide films, which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature. It also finds that aging for years significantly affected the nonstoichiometry of vanadium dioxide films, thus inducing much change in Raman modes.

Quest for carbon and vanadium oxide based rechargeable magnesium-ion batteries

Rechargeable magnesium ion batteries are potential candidates to replace the lithium ion batteries due to their high volumetric energy density,dendrite free cycling,and low costs.In present work,we have critically reviewed the recent advances made in the field of cathode materials development to achieve the high reversible capacities and working potentials.In first part,carbon-based cathodes such as fluorinedoped graphene nanosheets and graphite fluoride(CF0.8)are discussed in terms of compatibilities of pos让ive electrode materials and electrolyte solutions for rechargeable magnesium-ion batteries.Whereas,the second part of this review focuses on crystal structure of vanadium oxide and its capability to accommodate the Mg^2+ions.Likewise,electrochemical performance of selected vanadium oxide based cathodes including VO2(B),FeVO4.0.9H2(X Mc)2.5+yVO9+δ,RFC/V2O5 and V2O5/Graphene composite,are discussed at different temperatures.To support the future research on magnesium ion batteries,particularly positive electrode material developments,several innovative research directions are proposed.

Hydrothermal synthesis of vanadium oxide nanotubes by a facile route

Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VOx-NTs which have a layered structure. TG-DTA study indicates that V5+ cations in nanotubes are partially reduced to V4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VOx nanotubes from lamellar structure because of the presence of V4+ species.

Layered hydrated vanadium oxide as highly reversible intercalation cathode for aqueous Zn-ion batteries

Aqueous Zn-ion batteries(ZIBs)hold great potential in large-scale energy storage systems due to the merits of low-cost and high safety.However,the unstable structure of cathode materials and sluggish(de)intercalation kinetics of Zn2+pose challenges for further development.Herein,highly reversible aqueous ZIBs are constructed with layered hydrated vanadium oxide as a cathode material.The electrochemical performances are further tested with the optimized electrolyte of 3M Zn(CF3SO3)2 and a cut-off voltage of 0.4 to 1.3 V,exhibiting a remarkable capacity of 290mAh g−1 at 0.5Ag−1,and long-term cycling stability at high current density.Furthermore,the Zn2+storage mechanism of V3O7⋅H2O is recognized as a highly reversible(de)intercalation process with good structural stability,implying the potential application in the field of large-scale energy storage.

Hydrothermal Synthesis and Structure of [CH3NH3]2[(VⅣO)2(VⅤO4)2]:A New Layered Mixed-valence Vanadium Oxide Incorporated with Organic Cations

A new layered mixed valence vanadium oxide, [CH 3NH 3] 2[(V ⅣO) 2(V ⅤO 4) 2], which contains interlamellar organic cations was prepared under hydrothermal conditions and its single crystal structure was determined. It crystallizes in a triclinic system with space group P 1, a =0 625 59(8) nm, b =0 639 84(9) nm, c =0 747 19(10) nm, α =78 718(2)°, β =80 099(2)°, γ =77 100(2). The compound contains mixed valence V 4+ /V 5+ vanadium oxide layers constructed from VO 4 tetrahedra, pairs of edge sharing VO 5 square pyramid and methylamine with protonated organic amines occupying the interlayer space.

Modeling of conducting bridge evolution in bipolar vanadium oxide-based resistive switching memory

We investigate the resistive switching characteristics of a Cu/VOx/W structure. The VOx film is deposited by radio- frequency magnetron sputtering on the Cu electrode as a dielectric layer. The prepared VOx sample structure shows reproducible bipolar resistive switching characteristics with ultra-low switching voltage and good cycling endurance. A modified physical model is proposed to elucidate the typical switching behavior of the vanadium oxide-based resistive switching memory with a sudden resistance transition, and the self-saturation of reset current as a function of compliance current is observed in the test, which is attributed to the conducting mechanism is discussed in detail. growth pattern of the conducting filaments. Additionally, the related

High-performance zinc-ion batteries enabled by electrochemically induced transformation of vanadium oxide cathodes

Rechargeable aqueous zinc-ion batteries(ZIBs) have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electrochemical properties of ZIBs,cathode materials with prominent Zn^(2+) storage capability are highly needed.Herein,we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides.Specifically,K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes.The cathode presented superior Zn^(2+) storage capability in Zn(OTf)_(2) aqueous electrolyte,including high capacity of 321 mAh/g,fast charge/discharge ability(96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance.Mechanism analysis evidenced that in Zn(OTf)_(2) electrolyte,Zn^(2+) intercalation in the first discharge process promoted K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers to transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O nanoflakes,and the latter served as the Zn^(2+)-storage host in subsequent charge/discharge processes.Benefiting from open-framework crystal structure and sufficiently exposed surface,the Zn_(3+x)V_(2) O_7(OH)_(2)·2_H2 O nanoflakes exhibited high Zn^(2+) diffusion coefficient,smaller charge-transfer resistance and good reversibility of Zn^(2+) intercalation/de-intercalation,thus leading to superior electrochemical performance.While in ZnS04 aqueous electrolyte,the cathode material cannot sufficiently transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O thereby corresponding to inferior electrochemical behaviors.Underlying mechanism and influencing factors of such a transformation phenomenon was also explored.This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides,but also provides new insights into Zn^(2+)-storage electrochemistry.

Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in H2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. Catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. Furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 K）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

Synthesis, Structure Characterization and Biological Activity of Layered Vanadium Oxides [NH_3(CH_2)_2NH(CH_2)_2NH_3][V_6O_(14)]

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.

Modeling and experiments of N-doped vanadium oxide prepared by a reactive sputtering process

An original numerical model, based on the standard Berg model, is used to simulate the growth mechanism of Ndoped VOx deposited with changing oxygen flow in the reactive gas mixture. In order to compare with the numerical model, N-doped VOx films are prepared by reactive magnetron sputtering from a metallic vanadium target immersed in a reactive gas mixture of Ar＋O2＋N2. Both experimental and numerical results show that the addition of N2 to the process alleviates the hysteresis effect with respect to the oxygen supply. Film compositions obtained from the XPS analysis are compared to the numerical results and the agreement is satisfactory. The results also show that the compound of VN is only found at very low O concentration because of the replacement reaction of VN by O2 atoms with higher oxygen flow rate.

A new long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)/polybenzimidazole(PBI)amphoteric membrane for vanadium redox flow battery

A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO)and polybenzimidazole(PBI)for vanadium redox flow battery(VRFB)application.An acid-base pair structure formed between the imidazole of PBI and sulfonic acid of S-L-PPO resulted in lowered swelling ratio.It favors to reduce the vanadium permeation.While,the increased sulfonic acid concentration ensured that proton conductivity was still at a high level.As a result,a better balance between the vanadium ion permeation(6.1×10^-9 cm^2·s^-1)and proton conductivity(50.8 m S·cm^-1)in the S-L-PPO/PBI-10%membrane was achieved.The VRFB performance with S-L-PPO/PBI-10%membrane exhibited an EE of 82.7%,which was higher than those of pristine S-L-PPO(81.8%)and Nafion 212(78.0%)at 120 m A·cm^-2.In addition,the S-LPPO/PBI-10%membrane had a much longer self-discharge duration time(142 h)than that of Nafion 212(23 h).