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1.
镍钒合金电沉积及其析氢电催化性能的研究   总被引:1,自引:0,他引:1  
镍钒合金电沉积及其析氢电催化性能的研究林文修王树喜(福建师范大学化学系福州350007)关键词镍钒合金电镀电催化析氢反应对电化学的能量转换、电合成、金属沉积和防腐等具有重要意义,选择和探索优良的过渡金属电催化剂是研究析氢电催化阴极的主要方向。1978...  相似文献   

2.
纳米晶Ni—Mo—Co合金镀层的结构与析氢行为   总被引:7,自引:0,他引:7  
黄令  杨防阻  许书楷  周绍民 《应用化学》2001,18(10):767-771
用电沉积方法制备了纳米Ni-Mo-Co合金沉积层,用XRD、XPS方法对沉积层的结构进行了表征,结果表明,Ni-Mo-Co合金出现较大的晶格畸变,纳米合金各物种的结合能发生不同程度的位移。在30%的KOH溶液中的阴极极化曲线表明,Ni-Mo-Co合金电极具有良好的析氢电催化活性。电化学的交流阻抗谱表明,低过电位时该合金电极上析氢过程为Volmer-Tafel机理,即吸附态的氢经化学脱附形成氢气,速率决定步骤是Volmer反应;在较高过电位时析氢反应表现为Volmer-Heyrovsky机理,即吸附态的氢经电化学脱附形成氢气。  相似文献   

3.
张卫国  刘洋  李贺  姚素薇 《催化学报》2006,27(11):967-970
 采用电沉积方法制备了Ni-W-P合金镀层,并在不同温度下进行热处理,通过极化曲线和交流阻抗谱研究了热处理温度对Ni-W-P合金催化析氢性能的影响. 结果表明,经200 ℃热处理的Ni-W-P合金电极析氢过电位最低,在电流密度为8.0 mA/cm2时,其析氢过电位较未经热处理的Ni-W-P合金电极减小约110 mV. 该样品的析氢电化学反应电阻为17.1 Ω·cm2, 交换电流密度约为未经热处理的Ni-W-P合金的5.0倍,析氢反应表观活化能降低. 差示扫描量热法、 X射线衍射和扫描电镜测试结果表明, Ni-W-P合金镀层经200 ℃热处理后发生低温结构弛豫,平均晶粒尺寸由1.1增大到2.8 nm, 合金由非晶结构转变为纳米晶结构,镀层表面形成宽度约为0.2 μm的微裂纹.  相似文献   

4.
钛基体中离子注入镍和钼的电催化活性   总被引:2,自引:0,他引:2  
Grenness等发现,铂离子注入钨基体中,对H~+还原产生的电催化性能与纯铂相近,此后,Wolf等用离子注入和离子束混合技术制作了多种电极,其中Pt/RuO_2、Pt/C、Pt/WC电极用于H~+和O_2的电还原以及甲醇和甲酸的电氧化,其催化活性和稳定性均优于光滑的纯铂电极,目前,在其它方法制作的析氢电极材料中,最可能用于工业电解槽的为NiMo合金电极和复合Raney镍合金电极,本工作将镍和钼离子注入到钛基体中,研究了此电极在30 wt%KOH溶液中析氢电催化行为,并通过电子探针显微分析(EPMA)和X射线光电子能谱(XPS)分析,检测了离子注入电极的表面成分、注入元素的浓度分布及价态。  相似文献   

5.
非晶态Ni-S-Mn三元合金电极析氢行为   总被引:1,自引:0,他引:1  
非晶态Ni-S-Mn三元合金电极析氢行为;电极;析氢电催化活性;水电解;非晶态合金  相似文献   

6.
根据各种金属与氢原子形成M—H键的强度不同,设计并制备不同组成的二元合金电极。重点探讨了电极材料的组成与电催化性能之间的相互关系,可通过调节电极表面吸附氢原子的能力,降低析氢反应的活化能,提高整个过程的反应速度,减小析氢反应的过电位。  相似文献   

7.
周琦  李志洋 《无机化学学报》2018,34(12):2188-2196
采用快速凝固结合脱合金化的方法制备了纳米多孔Ni、Ni-Mo合金及其氧化物电极材料,通过XRD、SEM、TEM、BET等对电极的物相、形貌结构、孔径分布进行表征,通过线性扫描伏安法、Tafel斜率和计时电位等方法测试多孔电极的电催化析氢性能。结果显示,制备的电极材料在10 mA·cm-2电流密度下Ni-Mo合金析氢活性最强,析氢过程由Volmer-Heyrovsky步骤控制,其表观交换电流密度为0.25 mA·cm-2,经10 000 s恒电流密度(100 mA·cm-2)电解后析氢过电位(η)仅增加39 mV,表现出优良的析氢稳定性。Ni-Mo合金电极比表面积的提高和本征催化活性的改善使其获得了更低的析氢过电位。  相似文献   

8.
Ni-Sn电极析氢性能研究   总被引:6,自引:0,他引:6  
常天义  张宝宏  丛文博  骆耀 《电化学》2002,8(3):343-347
在Fe基底材料上电镀Ni-Sn合金制备低析氢过电位的阴极活性材料。该材料适用于氯碱工业隔膜型电解槽,可达到降低槽压、节能降耗的目的。在电解槽阴极溶液NaOH120g/L,NaCl190g/L;温度90℃,阴极极化电流密度i=150mA/cm^2的条件下,测得其析氢过电位为88mV.X射线衍射分析表明,该种材料与传统装饰用Ni-Sn合金的结构状态有所不同,采用循环伏安法对Fe电极和Ni-Sn合金电极进行分析,可初步判断Ni-Sn合金对氢的吸附较弱,有利于析氢反应的进行。  相似文献   

9.
Mo对脱合金制备的Ni-Mo电极骨架结构与析氢性能的影响   总被引:1,自引:0,他引:1  
采用快速凝固结合脱合金化方法制备了不同Mo含量的纳米多孔Ni-Mo合金,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和N2吸附-脱附分析等对多孔合金的物相、形貌结构及孔径分布进行了表征,并通过线性扫描伏安、Tafel斜率、交流阻抗和循环伏安等方法测试了多孔合金电极的电催化析氢性能.结果显示,多孔合金电极材料在50 mA/cm2电流密度下析氢过电位随着Mo含量的增加先降低后升高,Ni2.5Mo2.5合金析氢活性最强,过电位为218 mV,析氢过程由Volmer-Heyrovsky步骤控制,交换电流密度为0.29 mA/cm2,经1000周循环后的极化曲线基本保持原状,50 mA/cm2电流密度下过电位增加3.67%,表现出优良的析氢稳定性.  相似文献   

10.
W离子注入Ni-Mo合金电极的析氢性能   总被引:2,自引:0,他引:2  
本文在镍基上电沉积Ni-Mo合金层,用W^+束注入,得到活性和稳定性极佳的新型析氢电极。  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

16.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

17.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

18.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

19.
20.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

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