全钒液流电池高浓度下V(IV)/V(V)的电极过程研究

采用循环伏安、低速线性扫描和阻抗技术, 以石墨为电极, 研究了V(IV)/V(V)在较高浓度下的电极过程. 结果表明, 采用2.0 mol•L-1 的V(IV)溶液时, H2SO4浓度低于2 mol•L-1, V(IV)/V(V)反应极化大, 可逆性差, 表现为电化学和扩散混合控制; H2SO4浓度增至2 mol•L-1以上, V(IV)/V(V)反应的可逆性提高, 转为扩散控制, 且增加H2SO4浓度有利于阻抗的降低; 但H2SO4浓度超过3 mol•L-1, 溶液的粘度和传质阻力大, 阻抗反而增大. 在3 mol•L-1的H2SO4中, 随着V(IV)浓度的增加, 体系的可逆性和动力学改善, 阻抗减小; 但V(IV)浓度超过2.0 mol•L-1, 较高的溶液粘度导致溶液的传质阻力迅速增加, V(IV)/ V(V)的电化学性能衰减, 阻抗增大. 因此, 综合考虑电极反应动力学和电池的能量密度两因素, V(IV)溶液的最佳浓度为1.5～2.0 mol•L-1, H2SO4浓度为3 mol•L-1.     

检测器(V)

在本卷第３期上我们介绍了消除检测器噪声的电阻－电容（Ｒ／Ｃ）滤波器。该滤波器的电路虽然很简单,但对一些由于检测器电路本身所产生的噪声的消除却非常有效。图５是连接Ｒ／Ｃ滤波器前后的色谱基线谱图（注意图５－ａ,ｂ的Ｙ轴标值是不同的）。从图５－ｂ中可以看出该滤波器的滤波效果是很明显的。但Ｒ／Ｃ滤波器也不是万能的,它主要对消除叠加在正常基线上的噪声尖锐峰特别有效（见图６）,而对图７所示的基线噪声却无能为力。图５　使用Ｒ／Ｃ滤波器前后基线图ａ．使用前,ｂ．使用后。图６　使用Ｒ／Ｃ滤波前后色谱图ａ．使用前,…     

胶原纤维固化黑荆树单宁吸附V(V)的研究

研究了胶原纤维固化黑荆树单宁对V(V)的吸附。采用不同温度、pH值等条件进行吸附研究,并进一步探讨了固化黑荆树单宁的吸附动力学和吸附柱动力学及其吸附机理。结果表明,该材料对V(V)的吸附平衡符合Freund lich方程,温度对吸附平衡的影响不明显;吸附动力学可用拟二级速度方程来描述,该材料同时具有良好的柱动力学特性;V(V)的吸附过程可能存在三个反应,即V(V)与吸附剂之间发生氧化还原反应生成V(IV),V(IV)和-COOH之间发生离子交换反应,以及V(IV)与单宁的邻位羟基发生螯合。     

电场中双原子分子间的V—V传能

用含时微扰理论两态近法算是分子间振动能传递，导出了电场中分子间共振Ｖ－Ｖ传能的跃迁几率，态－态反应截面反应速度常数表达式。     

Spectrophotometric Studies of V(V) Complexes of N-Methylaminothioformyl-N′-phenylhydroxylamine

The violet-colored complexes of V(V) and N-methylaminothio-formyl-N′-phenylhydroxylamine are extractable into chloroform. The spectrophotometric studies have shown that 1:3 and 1:4 (metal:ligand) complexes predominate in the acidity range 6.5–9 N and 9.5–10.5 N HCl, respectively. The values of stability constants, stepwise and overall, have been calculated by following extended Leden and Yatsimirskii methods. The analytical suitability of the reagent for the microdetermination of vanadium has also been investigated.     

Maoecrystal V的全合成研究进展

综述了Maoecrystal V的4种全合成方法,并对其发展前景进行了展望。参考文献30篇。     

二安替比林对乙氧基苯甲烷吸光光度法测定微量V（V）

合成了新试剂二安替比林对乙氧基苯基甲烷，并研究了与Ｖ（Ｖ）的显色反应。在磷酸介质中和Ｍｎ（Ⅱ）－乳化剂ＯＰ的作用下，显色反应的产物为橙黄色，ε为２．９０×１０＾６，λｍａｘ＝４５０ｎｍ，测定Ｖ（Ｖ）的线性范围为４￣３２μｇ·Ｌ＾－１。用于中草药中微量Ｖ（Ｖ）的测定，结果满意。     

Synthesis of a Phosphoantigen Prodrug that Potently Activates Vγ9Vδ2 T-Lymphocytes

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Untersuchungen im System V−As

Zusammenfassung Im System V–As konnten bisher mit Sicherheit die Phasen VAs und V₃As nachgewiesen werden. Daneben bestehen Kristallarten nahe der Zusammensetzung V₂As. Die Verbindung VAs kristallisiert imB 31-Typ mit den Gitterkonstanten:a=6,304k X · E,b=5,867kX · E undc=3,327k X · E, während die Verbindung V₃As mit derA 15-Struktur:a= 4,74k X · E isotyp ist.Herrn Prof. Dr.A. Klemenc zum 70. Geburtstage zugeeignet.     

Role of the V(V)/ 1O2Complex in Oxidative Reactions in the H2O2/V(V)/AcOH System: Oxidation of Alkenes and Anthracenes

Anthracene and its alkyl derivatives undergo oxidation in the V^(V)/H₂O₂/AcOH system via a nonradical mechanism through the intermediate formation of the vanadium(V) complex with singlet dioxygen as a ligand. The ¹O₂molecule is transferred from this complex to an unsaturated substrate. The free singlet dioxygen ¹O₂(¹ _g ) is almost inactive toward anthracene in AcOH solution. Consequently, the vanadium(V) complex with singlet dioxygen is the only oxidant species active in the reaction. The ratio between the rate constant of the reaction of this complex with 2-ethylanthracene and the rate constant of its deactivation is an order of magnitude greater than the ratio between the rate constant of the reaction of dissolved free singlet dioxygen with the same substrate and the rate constant of its deactivation (physical quenching).     

Triisopropoxyniobium(V) and tantalum(V)bis-O,O′-dialkyl dithiophosphates

Summary Triisopropoxy bis(O,O-dialkyl dithiophosphates), (i-PrO)₃M[S₂P(OR)₂]₂ (M = Nb^v, Ta^v; R = n-Pr, i-Pr, i-Bu and Ph) have been prepared by reacting the appropriate triisopropoxymetal(V)dichloride, (i-PrO)₃MCl₂ (1 mol) with sodium/ammonium dialkyl dithiophosphates (2 mols)in THF. The monomeric products which are viscous liquids, soluble in common organic solvents and highly susceptible to hydrolysis, were characterized by i.r. and n.m.r. spectra which indicate a bidentate mode of attachment of dithiophosphato groups to the metal.     

氮化钛纳米线的结构特征及其对V(Ⅱ)/V(Ⅲ)的电极过程

采用水热法在钛片表面直接生长二氧化钛纳米线(TiO_2 NWs),随后通过氨氮还原转化为氮化钛纳米线(TiN NWs)。利用扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、循环伏安法(CV)和电化学阻抗谱(EIS)对材料的组成、微观结构和电极过程动力学的特征进行表征。结果表明,TiN NWs纳米线的直径约20-50 nm,长度超过5μm,其表面可能存在Ti-N键、Ti-O键和O-Ti-N键,这种含氮和含氧的化学态使得TiN NWs电极具有更好的电导性和电催化性能。TiN NWs电极对V(Ⅱ)/V(Ⅲ)离子表现出更好的可逆性,其电极反应电阻R_(ct)值比TiO_2 NWs和石墨电极分别小约20倍和10倍。同时,TiN NWs电极上V(Ⅲ)还原反应的速率常数为5.21×10~(-4 )cm·s~(-1),约是石墨电极(速率常数9.63×10~(-5 )cm·s~(-1)的5倍,这可归因于TiN NWs的一维纳米线微结构特征及其较高的电催化性能。     

I群-D2群V系数

本文讨论了I群-D₂群V系数,给出在I群单值表示下的计算值。将以I群为出发点的群分解链延伸到其D₂子群。还列出了D₂群V系数的计算结果。     

Analyse der Polyoxyäthylenverbindungen. V

Zusammenfassung Ein neues Verfahren zur Bestimmung der Oxyäthylengruppen wurde ausgearbeitet. Es beruht auf der Spaltung der Polyoxyäthylenverbindungen mit Jodwasserstoffsäure in statu nasoendi, die durch Einwirkung von Kaliumjodid und Phosphorsäure im Reaktionsgemisch hergestellt wird. Die bei der Spaltungsreaktion gebildete, dem Gehalt an Oxyäthylengruppen äquivalente Menge Jod wird mit Thiosulfat titriert.

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Summary A new method was worked out for determining oxyethylene groups. It is based on the splitting of polyoxyethylene compounds with nascent hydriodic acid that is prepared by the action of potassium iodide and phosphoric acid in the reaction mixture. The quantity of iodine produced in the cleavage reaction is equivalent to the content of oxyethylene groups present. It is titrated with thiosulfate.

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Résumé On a mis au point un procédé nouveau pour doser les groupements oxydes d'éthylène. Il repose sur la dissociation des composés polyoxyéthyléniques par l'acide iodhydrique naissant, préparé par action d'iodure de potassium et d'acide phosphorique dans le milieu réactionnel. On titre par le thiosulphate l'iode formé par la réaction de dissociation, en quantité équivalente à la teneur en groupements oxydes d'éthylène.

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IV. Mitteilung siehe¹.     

51V and 17O NMR studies of the mixed metal polyanions in aqueous V—Mo solutions

NaVO₃Na₂MoO₄ solutions acidified with HCl were studied at the atomic V/Mo ratios equal to 3 : 1, 1 : 1, 1 : 3, 1 : 6 and vanadium concentration [V] = 0.1, 0.04, 0.004 and 0.0004 M in the range pH 7-2. Their ⁵¹V NMR spectra (measured at H_ito = 7 T) were compared with those of VW solutions containing mixed metal complexes of known composition. The VMo₅O₁₉³⁻ (⁵¹V NMR chemical shift relative to VOCl₃, δ, −502 ppm), V₂Mo₄O₁₉⁴⁻ (δ −494), V₂Mo₄O₁₉³⁻ δ −507), V₉MoO₂₈⁵⁻ (δ −422, −492, −501, −512, −521.5) and HV₉MoO₂₈⁴⁻ polyanions (p.a.) have been found to be dominant mixed species in Na-V-Mo solutions. Along with them the V_itxMO_13-itxO^−itx−3₄₀ p.a.(x∼2–3) of the Keggin type (δ −496, −498, −516, −522) are supposed to be formed at pH < 4 in concentrated solutions ([V] > 0.01 M). The V₂Mo₆O₂₆⁶⁻ p.a., isolated at pH ∼ 5 as the sodium salt (solid state δ −482), seem to be present in concentrated Na-V-Mo solutions only as minor species. On dissolving the salt the V₂Mo₆O₂₆⁶⁻ p.a. mainly disproportionates into the complexes mentioned. From solutions containing mainly the V₉MoO₂₈⁵⁻ p.a. the sodium salt of V₁₀O₂₈⁶⁻ is crystallized. The V₉WO₂₈⁶⁻ p.a. are detected in VW solutions at V/W > 1. ¹⁷O and ⁹⁵Mo NMR spectra of some mixed complexes are described. The distribution diagrams for VMo and V-W solutions at [V] = 0.004 M and V/Mo(W) = 1:3, derived from their ⁵¹V NMR spectra, are given.     

Intermetallische Phasen mit β-Wolfram-Struktur (V3Pb,Nb3Pb und V3Cd)

Zusammenfassung Neue Phasen mit -Wolfram-Struktur (Cr₃O-Typ) werden in den Systemen V–Pb, Nb–Pb und V–Cd hergestellt und deren Gitterparameter bestimmt.     

氮化钛纳米管作为钒电池负极对V(Ⅱ)/V(Ⅲ)的电化学性能

采用阳极氧化法在钛箔表面原位生长二氧化钛纳米管,随后在氨气氛围中氮化还原制备氮化钛纳米管,并将此电极直接作为钒电池的负极,研究其对VⅡ/VⅢ的电化学性能。通过X射线衍射（XRD）、扫描电镜（SEM）以及X射线光电子能谱（XPS）等材料测试手段对氮化钛纳米管的形貌、组成和结构进行表征。分析结果表明,氨气高温氮化后,前驱体TiO₂相转变为TiN和Ti₂N相,表面元素组成为Ti-N-O,Ti-N和Ti-O,且其形貌仍保持纳米管的微观结构。采用循环伏安,电化学阻抗和充放电测试表明,氮化钛纳米管对负极电解液中的V（Ⅱ）/V（Ⅲ）展现了优异的电催化活性和可逆性,这主要归因于氮化钛纳米管大的电化学真实表面积和快速的电子转移通道。     

氮化钛纳米管作为钒电池负极对V(Ⅱ)/V(Ⅲ)的电化学性能

采用阳极氧化法在钛箔表面原位生长二氧化钛纳米管,随后在氨气氛围中氮化还原制备氮化钛纳米管,并将此电极直接作为钒电池的负极,研究其对V（Ⅱ）/V（Ⅲ）的电化学性能。通过X射线衍射（XRD）、扫描电镜（SEM）以及X射线光电子能谱（XPS）等材料测试手段对氮化钛纳米管的形貌、组成和结构进行表征。分析结果表明,氨气高温氮化后,前驱体TiO₂相转变为TiN和Ti₂N相,表面元素组成为Ti-N-O,Ti-N和Ti-O,且其形貌仍保持纳米管的微观结构。采用循环伏安,电化学阻抗和充放电测试表明,氮化钛纳米管对负极电解液中的V（Ⅱ）/V（Ⅲ）展现了优异的电催化活性和可逆性,这主要归因于氮化钛纳米管大的电化学真实表面积和快速的电子转移通道。     

Defect formation in manganese-doped III–V compounds

Point defect densities in manganese-doped III–V compounds, namely, GaAs, InP, InAs, and InSb, were calculated in terms of a joint thermodynamic model. Doping with an acceptor dopant enhances the role of vacancies of a volatile component and noticeably increases the density of anti-site defects B _A ^** . This effect strengthens as the bandgap width decreases and is most prominent in indium antimonide.