库仑滴定法测定钒电池电解液中钒(Ⅲ)与钒(Ⅳ)的含量

钒电池是利用不同价态的钒离子在硫酸电解质溶液中发生氧化还原反应,实现化学能与电能之间的相互转换,从而具有大容量的快速充放电且功率和容量可调节等优点,被相关行业认为是最佳新能源储存介质[1-2]。该电池的容量和充放电效率,与电解液中不同价态的钒离子浓度有关,而该电解液中的钒离子的起始状态通常为钒(Ⅲ,V3+)和钒(Ⅵ,VO2+)混合态,当两种离子浓度的比值为1时,电池比容量达到最大[3-4],因此如何简便、快速且高效的测定V3+和VO2+的含量,对产品的质量控制意义重大。     

电位滴定法测定钒电池电解液中不同价态的钒

钒电池是以钒离子溶液为正负极活性物质的蓄电池[1,2]。钒各种价态的化学行为都很活跃,其中VO 2/VO2 及V3 /V2 两电对电位相差约为1.25 V。钒电池的工作原理如下:正极:V(Ⅳ)→V(Ⅴ) e充电V(Ⅴ)→V(Ⅳ)-e放电负极:V(Ⅲ) e→V(Ⅱ)充电V(Ⅱ)-e→V(Ⅲ)放电基于钒电池具有优于其它氧化还原电池的特点,如无交叉污染、反应速度快、可深度放电、易于增减电池功率和容量等,因而有着广泛的用途,如电网调峰、应急电源、动力电源等。由于钒电池正负极的活性物质均为钒离子,钒离子的电化学反应程度决定着电池的充放电效率,因此有必要建立一种经济、简便、安全、有效的价态钒分析方法。价态钒的分析方法主要有发射光谱法和电位滴定法等,目前钒电池用电解液中价态钒的分析以电位滴定为主,但报道的均是使用毒性较强、对人体危害较大的重铬酸钾作为滴定剂[3,4],而且操作相对繁琐。本法提出了一种以硫酸亚铁铵溶液为滴定剂的安全、简便、有效的各种价态钒的电位滴定分析方法。1试验部分1.1分析原理在强酸性介质中,4种价态钒离子不能3种以上共存,高价钒与低价钒氧化还原反应,这个反应是完全的也是定量的。因此本法以下面三个化学反应...     

Mn2+浓度对钒液流电池正极液的电化学性能影响

电解液中金属离子会影响钒液流电池的电化学性能。本文采用循环伏安法和电化学阻抗谱研究了正极液中Mn2+浓度对V髨/V(Ⅳ)电对的氧化还原过程影响规律,发现Mn2+在正极液中没有发生副反应,但严重影响V髨/V(Ⅳ)的反应活性、电极反应可逆性、离子扩散与电荷转移反应等电化学性能。循环伏安测试结果表明Mn2+浓度为0.04-0.13 g.L-1时,V髨/V(Ⅳ)电对电极反应可逆性和反应活性较高,钒离子扩散系数由参照溶液中的8.89×10-7-1.098×10-6增大至1.302×10-6-1.800×10-6 cm2.s-1,提高了-60%;电化学阻抗测试结果表明Mn2+浓度为0-0.04 g.L-1时,V髨/V(Ⅳ)电对电极反应阻抗和界面阻抗均较参照溶液中的增加不明显,但当Mn2+浓度增至0.07 g.L-1时,上述阻抗值较参照溶液增大了25%-28%。基于二者结果,Mn2+对电极反应有不同程度的负面影响,但是适当的Mn2+浓度有利于钒离子的扩散。     

甘氨酸为络合剂时钯和葡萄糖氧化酶的电化学共沉积研究

甘氨酸和Pd(NH3 ) 2 Cl2 组成镀液 ,用于钯和葡萄糖氧化酶 (GOD)的电化学共沉积以制备金属化酶电极、UV/V光谱实验表明甘氨酸能与Pd2 + 离子发生络合作用 ,并使镀液在一定 pH范围内具有较稳定的化学组成 .伏安法实验证实甘氨酸的存在降低了Pd的沉积电位 ,有利于防止钯氢化合物的形成 .讨论了钯和GOD电化学共沉积的合适条件 .     

甲基磺酸亚锡溶液中不同稳定剂的作用机制及电化学性质

研究了对苯二酚、邻苯二酚、间苯二酚和抗坏血酸4种稳定剂对甲基磺酸亚锡电镀液稳定性、电极极化及镀层表面形貌的影响.采用循环伏安法探究了镀液稳定性与稳定剂电化学性质的关系,通过交流阻抗和计时电位考察了稳定剂对镀液阴极极化性能的影响,分析了对苯二酚在电镀过程中的循环使用原理及对苯二酚的最佳使用浓度.结果表明,镀液的稳定性与稳定剂自身的还原能力及电化学活性之间存在重要联系,4种稳定剂对镀液稳定作用的大小顺序为对苯二酚邻苯二酚抗坏血酸间苯二酚,稳定效果最好的对苯二酚可以将镀液的储存时间延长一倍;苯二酚类稳定剂可以提高锡沉积的阴极极化程度,使晶粒细化,而抗坏血酸对锡沉积起到去极化作用;对苯二酚在电镀锡过程中兼具抗氧化剂、光亮剂和整平剂的作用,镀层的耐蚀性能测试结果表明,对苯二酚的最佳浓度为1.0 g/L.     

四羟基蒽醌修饰活性炭碳糊电极流动注射安培法测定铬(Ⅵ)

报道了将四羟基蒽醌吸附在稻壳基活性炭上 ,用直接混合法制备成化学修饰电极及其在测定Cr 中的应用。研究表明 ,Cr 的电还原产物Cr 可被该电极吸附 ,产生较灵敏的后行吸附。通过实验考察 ,确定了流动注射安培法测定Cr 的最佳操作条件。支持电解质为 0 .0 6mol/L的H2 SO4,在 - 0 .6V电位下作计时电流法测定 ,该电极对Cr 在 5 .0× 10 -6～ 1.0× 10 -3 mol/L范围内有良好的线性响应 ;检出限为 4 .3×10 -7mol/L ;Mg2 + 、Mn2 + 、Al3 + 和Fe3 + 等 10余种共存离子基本不干扰。每次进样后用底液洗脱 5 0s ,可不必更新电极表面。     

Keggin型钼钒磷杂多酸催化剂上丙烷选择氧化性能的研究

系统研究了不同数目V⁵⁺取代的钼钒磷杂多酸H_3+nPMo_12－nV_nO₄₀ (n＝0～4)催化剂上丙烷选择氧化反应性能. 通过BET, IR, TPR, 紫外-可见光谱等表征手段对催化剂的理化性质进行了考察, 并对催化剂的结构-性能关系进行了初步关联. 在杂多酸的一级结构中, V⁵⁺对Mo⁶⁺的取代不仅改变了杂多阴离子金属-氧桥的键强以及晶格氧的插入能力, 而且也相应地调变了样品的酸量. 催化剂活性随V⁵⁺取代数量的递增而增强; 适宜数量的V⁵⁺取代提高了含氧酸产物的选择性, 而过量的V⁵⁺取代则导致部分氧化产物的深度氧化. 考察了在Keggin型杂多酸二级结构上引入钒物种的影响, 也即将钒物种(VO)²⁺作为抗衡离子取代部分质子以调变催化剂的结构与性质. 实验表明, 处于一级结构和二级结构[(VO)²⁺抗衡离子]中的V在反应中均可离析出少量V₂O₅物种. 适宜量的(VO)²⁺物种以及离析出来的少量V₂O₅物种可能均对催化剂的性能有贡献. 显然, 钒在不同位置的价态变化以及形态的不同, 会导致催化性能的相应改变.     

结构原子组成对Keggin型杂多酸铯盐上丙烷选择氧化性能的影响

系统地研究了具有不同结构原子组成的Keggin型杂多酸铯盐上丙烷选择氧化性能,重点考察了H3+n-xCsxPMo12-nVnO40(n=0-4,x=0-3)系列化合物以及H0.5Cs2.5PW12O40,H1.5Cs2.5PW11VO40和H1.5Cs2.5SiMo12O40样品.应用BET,UV-Vis,FTIR,XRD,TPR和SEM等手段研究了催化剂的物化性质.V取代Mo增加了H3+nPMo12-nVnO40(n=0-4)系列杂多酸的酸量和氧化性能.Cs+对质子的取代调变了样品的表面酸性以及氧化还原性,同时催化剂的热稳定性也随着Cs+取代数的递增而增强,当Cs+的取代数达到2以上时催化剂的热稳定性较好.Cs+取代对H3+n-xCsxPMo12-nVnO40(n=0-4,x=0-3)催化剂上丙烷选择氧化性能有重要影响.随着一级结构中V5+取代数目的增多,可能的Cs+取代数目相应减少;而对丙烯酸的选择性则存在一适宜的Cs+取代数目.Keggin型杂多阴离子的结构原子组成及平衡离子的种类和数量决定了其酸性、氧化还原性和热稳定性,这是影响该类催化剂上丙烷选择氧化性能的首要因素.研究结果表明,以P为中心原子,以Mo和V为配位原子的杂多酸铯盐[x(Cs+)=2.5]具有较好的催化性能.     

KSCN对钒电池正极反应动力学及电池性能的影响

应用循环伏安、交流阻抗(EIS)等方法,研究了硫氰酸钾(KSCN)添加剂对石墨电极上(正极)钒电池电对(VO2+/VO2+)动力学特征及电池性能的影响.结果表明:1)KSCN的添加提高了VO2+/VO2+电对氧化峰的峰电流,但对还原峰的影响很小;2)添加KSCN,增加了充放电电量,提高了钒电池中活性物质的利用效率;3)VO2+/VO2+电对的速率常数K0,随着KSCN浓度的增加而逐渐增大.     

酸性介质中碘离子在铂电极上的电化学氧化行为

采用循环伏安法研究了酸性介质中碘离子在铂电极上不同电位区间, 不同酸度下的电化学反应行为. 结果表明, 当极化电位较低(小于0.6 V(vs Hg/Hg2SO4))时, 碘离子在铂电极上发生2I--2e→I2电氧化反应, 反应产物通过I2+I-=I-3被进一步溶解, 整个反应属于E-C(electrochemical-chemical)模式. 电氧化过程中可以形成碘膜, 其也可以被碘离子溶解. 当极化电位升高至0.6 V(vs Hg/Hg2SO4)或以上时, 碘离子会直接电氧化为高价态碘化合物, I-+3H2O→IO-3+6H++6e, 而析出的碘膜并不发生再氧化反应; 在电化学还原过程中, 出现了两个还原峰, 分别对应于I2、I-3的还原反应; 在无碘膜时, 碘离子电氧化过程受溶液中碘离子的液相扩散步骤控制; 碘膜形成后, 主要受碘膜中碘离子的固相扩散控制; 酸度对于碘离子的电化学氧化过程有很大的影响, 其线性极化曲线的起峰电位及电流峰值电位均随酸浓度升高而负移.     

Synthesis and characterization of vanadium(IV) complexes with cis-inositol in aqueous solution and in the solid-state

The complex formation of vanadium(IV) with cis-inositol (ino) and the corresponding trimethyl ether 1,3,5-trideoxy-1,3,5-trimethoxy-cis-inositol (tmci) was studied in aqueous solution and in the solid-state. With increasing pH, the formation of [VO(H-2L)], [(VO)2L2H-5]-, [VO(H-3L)]- (L = ino) or [(VO)2L2H-6]2- (L = tmci), [V(H-3L)2]2-, and [VO(H-3L)(OH)2]3- was observed. For the vanadium(IV)/ino system, [(VO)2L2H-7]3- was observed as an additional dinuclear species. The formation constants of these complexes were determined by potentiometric titrations (25 degrees C, 0.1 M KCl). In addition, the vanadium(IV)/ino system was investigated by means of UV-vis spectrophotometric methods. EPR spectroscopy and cyclic voltammetry confirmed this complexation scheme. EPR measurements indicated the formation of three distinct isomers of the non-oxo complex [V(H-3ino)2]2- in weakly basic solution. This type of isomerism, which is not observed for the vanadium(IV)/tmci system, was assigned to the ability of ino to bind the vanadium(IV) center with three alkoxo groups having either a 1,3,5-triaxial or an 1,2,3-axial-equatorial-axial arrangement. The structures of [V(H-3ino)2][K2(ino)2].4H2O (1) and [Na6V(H-3ino)2](SO4)2.6H2O (2) were determined by single-crystal X-ray analysis. In both compounds, the coordination of each ino molecule to the vanadium(IV) center via three axial deprotonated oxygen donors was confirmed. The centrosymmetric structure of the coordination spheres corresponds to an almost regular octahedral geometry with a twist angle of 60 degrees. The crystal structure of the potassium complex 1 represents an unusual 1:1 packing of [V(H-3ino)2]2- dianions and [K2(ino)2]2+ dications, in which both K+ ions have a coordination number of nine and are bonded simultaneously to a 1,3,5-triaxial and an 1,2,3-axial-equatorial-axial site of ino. In 2, the [V(H-3ino)2]2- complexes are surrounded by six Na+ counterions that are bonded to the axial alkoxo oxygens and to the equatorial hydroxy oxygens of the cis-inositolato moieties. The six Na+ centers are further interlinked by bridging sulfate ions. According to EPR spectroscopy, the D3d symmetric structure of the [V(H-3ino)2]2- anion is retained in H2O, in dimethylformamide, and in a mixture of CHCl3/toluene 60:40 v/v.     

4-amino- and 4-nitrodipicolinatovanadium(V) complexes and their hydroxylamido derivatives: synthesis, aqueous, and solid-state properties

A number of 4-substituted, dipicolinatodioxovanadium(V) complexes and their hydroxylamido derivatives were synthesized to characterize the solid state and solution properties of five- and seven-coordinate vanadium(V) complexes. The X-ray crystal structures of Na[VO2dipic-NH2].2H2O (2) and K[VO2dipic-NO2] (3) show the vanadium adopting a distorted, trigonal-bipyramidal coordination environment similar to the parent coordination complex, [VO2dipic]- (1), reported previously as the Cs+ salt. The observed differences in the chemical shifts of the complexes both in the 1H (ca. 0.7-1.4 ppm) and 51V (ca. 1-11 ppm) NMR spectra were consistent with the electron-donating or electron-withdrawing properties of the substituent groups, respectively. Stoichiometric addition of a series of hydroxylamine ligands (H2NOH, MeHNOH, Me2NOH, and Et2NOH) to complexes 1-3 led to the formation of seven-coordinate vanadium(V) complexes. The X-ray crystal structure of [VO(dipic)(Me2NO)(H2O)].0.5H2O (1c) was found to be similar to the previously characterized complexes [VO(dipic)(H2NO)(H2O)] (1a) and [VO(dipic)(OO-tBu)(H2O)]. While only slight differences in the 1H NMR spectra were observed upon addition of the hydroxylamido ligand, the signals in the 51V NMR spectra change by up to 100 ppm. The addition of the hydroxylamido ligand increased the complex stability of complexes 2 and 3. Evidence for a nonstoichiometric redox reaction was found for the monoalkyl hydroxylamine ligand. The reaction of an unsaturated five-coordinate species with a hydroxylamine to form a seven-coordinate vanadium complex will, in general, dramatically increase the amounts of the vanadium compound that remain intact at pH values near neutral.     

Protonation Equilibria of Mononuclear Vanadate: Thermodynamic Evidence for the Expansion of the Coordination Number in VO(2)(+)

A spectrophotometric investigation of the protonation of HVO(4)(2-) has been conducted at vanadium(V) concentrations low enough (5 x 10(-5) mol dm(-3)) to prevent the formation of polynuclear ions. Equilibrium constants as well as enthalpy and entropy changes for the formation of H(2)VO(4)(-) and VO(2)(+) have been determined in ionic medium: 1.0 mol dm(-3) NaCl and NaClO(4), respectively. The percentage concentration of the neutral species, H(3)VO(4), is so low (apparently <1%) that the protonation of H(2)VO(4)(-) to form VO(2)(+) occurs virtually in a single step. The disproportionately great stability of VO(2)(+) relative to H(3)VO(4) is explained in terms of an increase in the coordination number of vanadium when the cationic species is formed. This explanation is based on a comparison of the thermodynamic quantities of the vanadium(V) species with those of various other oxyacids reported in the literature.     

Experimental and theoretical study of the reactions between neutral vanadium oxide clusters and ethane, ethylene, and acetylene

Reactions of neutral vanadium oxide clusters with small hydrocarbons, namely C2H6, C2H4, and C2H2, are investigated by experiment and density functional theory (DFT) calculations. Single photon ionization through extreme ultraviolet (EUV, 46.9 nm, 26.5 eV) and vacuum ultraviolet (VUV, 118 nm, 10.5 eV) lasers is used to detect neutral cluster distributions and reaction products. The most stable vanadium oxide clusters VO2, V2O5, V3O7, V4O10, etc. tend to associate with C2H4 generating products V(m)O(n)C2H4. Oxygen-rich clusters VO3(V2O5)(n=0,1,2...), (e.g., VO3, V3O8, and V5O13) react with C2H4 molecules to cause a cleavage of the C=C bond of C2H4 to produce (V2O5)(n)VO2CH2 clusters. For the reactions of vanadium oxide clusters (V(m)O(n)) with C2H2 molecules, V(m)O(n)C2H2 are assigned as the major products of the association reactions. Additionally, a dehydration reaction for VO3 + C2H2 to produce VO2C2 is also identified. C2H6 molecules are quite stable toward reaction with neutral vanadium oxide clusters. Density functional theory calculations are employed to investigate association reactions for V2O5 + C2H(x). The observed relative reactivity of C2 hydrocarbons toward neutral vanadium oxide clusters is well interpreted by using the DFT calculated binding energies. DFT calculations of the pathways for VO3+C2H4 and VO3+C2H2 reaction systems indicate that the reactions VO3+C2H4 --> VO2CH2 + H2CO and VO3+C2H2 --> VO2C2 + H2O are thermodynamically favorable and overall barrierless at room temperature, in good agreement with the experimental observations.     

Syntheses and crystal structures of a series of alkaline earth vanadium selenites and tellurites

Six new novel alkaline-earth metal vanadium(V) or vanadium(IV) selenites and tellurites, namely, Sr(2)(VO)(3)(SeO(3))(5), Sr(V(2)O(5))(TeO(3)), Sr(2)(V(2)O(5))(2)(TeO(3))(2)(H(2)O), Ba(3)(VO(2))(2)(SeO(3))(4), Ba(2)(VO(3))Te(4)O(9)(OH), and Ba(2)V(2)O(5)(Te(2)O(6)), have been prepared and structurally characterized by single crystal X-ray diffraction analyses. These compounds exhibit six different anionic structures ranging from zero-dimensional (0D) cluster to three-dimensional (3D) network. Sr(2)(VO)(3)(SeO(3))(5) features a 3D anionic framework composed of VO(6) octahedra that are bridged by SeO(3) polyhedra. The oxidation state of the vanadium cation is +4 because of the partial reduction of V(2)O(5) by SeO(2) at high temperature. Ba(3)(VO(2))(2)(SeO(3))(4) features a 0D [(VO(2))(SeO(3))(2)](3-) anion. Sr(V(2)O(5))(TeO(3)) displays a unique 1D vanadium(V) tellurite chain composed of V(2)O(8) and V(2)O(7) units connected by tellurite groups, forming 4- and 10-MRs, whereas Sr(2)(V(2)O(5))(2)(TeO(3))(2)(H(2)O) exhibits a 2D layer consisting of [V(4)O(14)] tetramers interconnected by bridging TeO(3)(2-) anions with the Sr(2+) and water molecules located at the interlayer space. Ba(2)(VO(3))Te(4)O(9)(OH) exhibits a one-dimensional (1D) vanadium tellurite chain composed of a novel 1D [Te(4)O(9)(OH)](3-) chain further decorated by VO(4) tetrahedra. Ba(2)V(2)O(5)(Te(2)O(6)) also features a 1D vanadium(V) tellurites chain in which neighboring VO(4) tetrahedra are bridged by [Te(2)O(6)](4-) dimers. The existence of V(4+) ions in Sr(2)(VO)(3)(SeO(3))(5) is also confirmed by magnetic measurements. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory (DFT) methods indicate that all six compounds are wide-band gap semiconductors.     

一个二核钒配合物的合成及晶体结构：NH4[(VⅣO)2(μ2-O)(nta)2][EuⅢ(H2O)9](英)

A binuclear vanadium complex NH₄[(V^ⅣO)₂(μ₂-O)(nta)₂][Eu^Ⅲ(H₂O)₉] was synthesized by reaction of NH₃VO₃, nitrilotriacetic acid and EuCl₃ in one aqueous solution. The crystal X-ray analysis shows that the complex contains one binuclear vanadium anion [(V^ⅣO)₂(μ₂-O)(nta)2]^4- and one [Eu^Ⅲ(H₂O)₉]³⁺ cation. The molecules are built up to a three-dimensional supramolecular structure through hydrogen bonding. CCDC: 238716.     

Vanadium(IV,V) complexes of D-saccharic and mucic acids in aqueous solution

The vanadium(IV,V) complexes formed with two aldaric acids (D-saccharic or D-glucaric acid, and mucic or galactaric acid) in aqueous solution were characterised by employing pH-potentiometry, EPR, multinuclear NMR and UV-VIS spectroscopy. The stoichiometry and stability constants of the complexes formed were determined at 25 degrees C and ionic strength I= 0.2 mol dm(-3)(KCl). The spectral measurements revealed that vanadium(IV,V) coordinates first at the terminal COO(-) functions, forming mononuclear complexes. At pH > 3, through the metal ion-induced deprotonation and coordination of the neighbouring alcoholic functions, (COO(-), O(-)) coordinated dinuclear complexes are formed, which predominate in the pH range 4-8. In the basic pH range, the ligand molecules are displaced and binary metal hydroxo and oxo complexes are present. EPR measurements at room temperature and at 140 K proved that formation of the VO(iv) dimers is more enhanced at room temperature, but at 140 K their dissociation is favoured. An interesting pH-dependent cis-trans isomeric equilibrium was assumed and analysed by EPR and molecular modelling in the case of the complexes [(VO)(2)L(2)H(x)](x=-2 and -4). Joint evaluation of the pH-potentiometric and (51)V NMR measurements revealed that both aldaric acids are able to bind an excess of vanadium(V), through the formation of oligomeric 2:1 and 3:2 species, besides the 2:2 species formed with VO(IV).     

Electron spin resonance study on the vanadium adsorption by persimmon tannin gel

The persimmon tannin gel can adsorb vanadium highly effectively from aqueous solutions containing VOCl(2) and NH(4)VO(3), respectively. The adsorption of vanadium from the VOCl(2) solution had a broad maximum at around pH 5-6, while that from the NH(4)VO(3) solution, a sharp maximum at around pH 3.75 and a broad one at around pH 5-6. The adsorption of vanadium by the gel from both VOCl(2) and NH(4)VO(3) solutions was rapid, and was obeyed the Langmuir adsorption isotherm. The ESR spectrum of VO(2+) in the persimmon tannin gel showed a typical powder pattern with g-anisotropy and anisotropic hyperfine structure (I=7/2), with g(//)=1.937, g( perpendicular)=2.005, mid R:A(//)mid R:=552 MHz, and mid R:A( perpendicular)mid R:=168 MHz, suggesting a square pyramidal coordination structure of VO(2+)-persimmon tannin complex. The ESR analysis of vanadium adsorption from the NH(4)VO(3) solution (pH 6) indicated the reduction of VO(3)(-) to VO(2+). The high vanadium-adsorption ability of the persimmon tannin gel from the VOCl(2) solution was attributed to the stable complex formation of VO(2+) with catechol and pyrogallol groups in the gel, while the vanadium adsorption from the NH(4)VO(3) solution can be explained as the combination of H(3)VO(4) and VO(2+) adsorptions.     

Separation of vanadium isotopes by ion-exchange chromatography

Cation-exchange displacement chromatography of VO2+ was carried out for studying vanadium isotope effects in carboxylate ligand-exchange systems. The heavier isotope 51V was enriched in the carboxylate complex solution. The isotope separation coefficients epsilon(= alpha-1) for 50V/51V were 2.2 x 10(-4) and 2.4 x 10(-4) for citrate and lactate systems at 298 K, respectively. These values are much larger than those obtained in a previous study on the malate system. The existence of binuclear complexes of VO2+ may create the conditions for larger isotope fractionation. From the viewpoint of the process development of isotope separation, the heights equivalent to a theoretical plate of these processes were analyzed and found to be very small in each system due to the homogeneous, small and highly porous resin used. Citrate may be better than the other tested systems for the vanadium isotope separation.     

Electronic structure of vanadium oxide. Neutral and charged species, VO0,+/-

The diatomic molecule vanadium oxide, VO, and its charged species VO+ and VO- were studied by multireference and coupled cluster methods in conjunction with large basis sets. The investigation of 22 states and the construction of 21 full potential energy curves allowed for a detailed understanding of the electronic structure of these species. Our best binding energies for the ground states of VO (X4Sigma-), VO+ (X3Sigma-), and VO- (X3Sigma-) were De = 150, 138, and 143 kcal/mol, respectively, in harmony with the corresponding experimental values. For both species VO and VO+ and for all states studied, the bonding showed a strong ionic character conforming to the models V+O- and V2+O-.