高透量 PdAu/陶瓷复合膜的表征与性能评测

 采用化学镀方法在非对称氧化铝管状载体上制备出高性能 PdAu 合金膜. 采用阶段性热处理方法通过 X 射线衍射技术监测 PdAu 膜层合金化进程, 发现在 823 K 下 H2 气氛中厚度为 2 μm, Au 含量为 17.37% 的 PdAu 双金属膜层需要 200 h 达到完全合金化; N2/H2 气氛对 PdAu 合金化速率无显著影响, 但 N2 气氛中合金化后的 PdAu 合金膜表面粒子烧结更为严重. 在 623~823 K 下, 与未进行化学镀 Au 时的纯 Pd 膜相比, PdAu 合金膜的 H2 渗透速率平均增加 1.68 倍, 透氢活化能 (Ea) 降低 38.51%; 当温度低于 573 K 时, PdAu 合金膜的 Ea 由高温时的 8.83 kJ/mol 增加到 15.75 kJ/mol, 此时 PdAu 合金膜的 H2 渗透控速步骤由体相扩散为主的 H2 传质步骤过渡到由表面扩散为主的传质步骤. 通过扫描电镜和能谱联用仪对 PdAu 合金膜的膜厚度和截面组成进行了表征. 关键词     

钯银膜无电解镀共沉积的探讨

无电解镀共沉积钯银合金膜是纯化氢同位素最有发展前途的方法之一 .膜的制备技术有物理气相沉积法 [1 ]、化学气相沉积法 [2 ]、电镀 [3]和无电解镀法 [4]等 .无电解镀法使用设备简单、易于操作 ,而且可以均匀地沉积在形状复杂、硬度不同的基体上 .国内对电镀钯及有关钯银合金膜的研究 [5]较多 ,但无电解镀的研究甚少 .本文用无电解镀法制备含银量在摩尔分数2 3%～ 2 5 %的有支撑钯银膜 (膜厚为 3～ 5μm) .采用含有钯银两种离子的镀液制得的膜层 ,优于机械混合的均匀程度 .结果表明膜层没有合金化 .无电解镀条件为 :镀温 (5 0± 1 )℃ ,镀…     

Cu含量对Ni-Cu-P化学镀层组织结构和性能影响

利用化学镀法制备出Ni-Cu-P合金镀层,研究了镀液中CuSO4·5H2O含量对合金镀层沉积速率和成分的影响. 通过XRD和SEM表征了不同CuSO4·5H2O质量浓度下Ni-Cu-P合金镀层的组织结构和表面形貌,运用极化曲线评价了合金镀层在质量分数为3.5%NaCl溶液中的耐蚀性能. 结果表明,随着镀液中CuSO4·5H2O质量浓度的增加,镀层沉积速率和P含量不断下降,Ni-P镀层中P的质量分数为14.98%. 当镀液中CuSO4·5H2O质量浓度为1.0 g/L时,P的质量分数为4.21%;镀层中Cu的含量随着镀液中CuSO4·5H2O含量的增加而增加. 当添加量为1.0 g/L时,镀层中Cu的质量分数达19.04%;镀层的结晶度随着Cu含量的上升不断增大,Cu的加入使镀层的表面形貌更加光滑;镀层的耐蚀性能随着镀液中CuSO4·5H2O含量的增加先上升后下降,当镀液中CuSO4·5H2O质量浓度为0.4 g/L时,Ni-Cu-P镀层表现出最优的耐蚀性能.     

陶瓷基钯银合金膜制备技术及性能研究

报道采用浆料涂敷与化学镀相结合法在陶瓷支撑上沉积钯银合金膜,采用浆料涂敷法,将含钯银的浆料涂敷在支撑体上,干燥后热分解,使支撑体表面沉积部分钯银。然后,采用化学镀在50℃下沉积钯银膜,热处理后,得到表面较光洁、厚度约为3μm、银含量为23%(原子百分含量)、合金化较完全的钯银合金膜,该膜在压差为0.1MPa,温度为300℃时的渗氢通量达45cm^3(STP)/(cm^2·min),分离因子达500,研究了钯银合金膜中银含量随热处理温度的变化规律,由实验结果发现,银逐渐向表面扩散,并在一定的温度条件达到基本平衡。     

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 .     

硬脂酸单分子膜上电沉积Ag膜的研究

通过电沉积方法,以气/液界面上形成的硬脂酸单分子膜为模板诱导沉积金属银膜.考察了镀液pH值、单分子膜表面压及沉积电位对银膜形貌及结构的影响.实验发现,酸性镀液的气/液界面上形成的单分子膜不能诱导沉积银,而在中性和碱性镀液的气/液界面上可以诱导银膜的生长.当单分子膜处于液态或固态时,气/液界面有银膜形成;液态单分子膜上的银膜生长速度较快,且银膜的结构一致.随着电极电位的升高,银膜沉积的速度加快,呈环状向外生长的圆形银膜逐渐变得不规则.将不同实验条件下的银膜转移出来,采用扫描电镜(SEM)、透射电镜(TEM)对银膜的结构与形貌进行了表征.研究表明,银首先在单分子膜上异相成核,由八面体构型逐渐发展成星型,最终在气/液界面形成具有松枝状微观结构的光亮银膜.     

陶瓷基钯银合金膜制备技术及性能研究

报道采用浆料涂敷与化学镀相结合法在陶瓷支撑上沉积钯银合金膜,采用浆料涂敷法,将含钯银的浆料涂敷在支撑体上,干燥后热分解,使支撑体表面沉积部分钯银。然后,采用化学镀在50℃下沉积钯银膜,热处理后,得到表面较光洁、厚度约为3μm、银含量为23%(原子百分含量)、合金化较完全的钯银合金膜,该膜在压差为0.1MPa,温度为300℃时的渗氢通量达45cm^3(STP)/(cm^2·min),分离因子达500,研究了钯银合金膜中银含量随热处理温度的变化规律,由实验结果发现,银逐渐向表面扩散,并在一定的温度条件达到基本平衡。     

NafionTM膜表面改性用等离子体聚合方法提高膜的阳离子选择性

采用辉光放电等离子体聚合方法 ,以 C2 H4 和 NH3 为单体 ,在 Nafion TM膜表面沉积一层含氨基及酰氨基的类聚乙烯阴离子交换膜 ,提高了 Nafion TM膜对阳离子的选择性 ,同时不显著增加膜电阻 .由 SEM确定该等离子体聚合膜厚约 0 .5μm,用红外光谱及 X光电子能谱表征膜结构 .采用四电极法测量膜电阻 ,膜对质子的选择性由 Cu2 + 的迁移数 t Cu表征 ,用二室隔膜装置 (0 .2 5mol/L Cu Cl2 -0 .5mol/L HCl|等离子体处理膜 |1 mol/L HCl)测量 t Cu. O2 等离子体预处理 Nafion TM膜有利于沉积膜在 Nafion TM膜上的沉积并与 Nafion TM膜紧密结合 .经改性后的 Nafion TM膜电阻值仍然很小 ,在 1 mol/L HCl溶液中电阻小于 0 .5Ω· cm2     

单晶硅表面贵金属晶粒层的制备

将预处理过的单晶硅p-Si(100)浸入含贵金属盐的HF溶液, 制备了Ag, Au, Pd和Pt的晶粒层. 用原子力显微镜(AFM)、开路电位(OCP)、循环伏安(CV)和交流阻抗(A. C. Impedance)方法对晶粒层性能进行了考察. 形貌显示, 在浸镀20 s后, Ag和Pd晶粒层基本上覆盖了硅基底, Ag颗粒致密, Pd颗粒之间仍有空隙且晶粒较Ag大. Au晶粒层部分覆盖了基底, 而Pt只有极少数的晶粒. 60 s后, Ag, Pd和Au晶粒层都完全覆盖了基底, 而Pt晶粒仍然较少, 但晶粒有所长大. 循环伏安显示, Pd的溶出峰电流比Ag, Au, Pt高1个数量级. 交流阻抗测量表明, Pd晶粒层阻抗最小. 结果表明, Ag, Pd和Au都能用浸入沉积的方法在单晶硅上短时间内制备出晶粒层, 而Pt不能, 选用哪种晶粒层, 需要根据后续工序和实际需要而定.     

清液体系中T型分子筛膜的高重复性合成与渗透汽化性能

以自制微米级分子筛为晶种,在清液体系中成功合成出高性能的T型分子筛膜,考察了硅铝比、水硅比、碱度及合成温度与时间等条件对膜的生长和渗透汽化性能的影响.结果表明,在摩尔组成为1SiO₂:0.015Al₂O₃:0.41(Na₂O+K₂O):30H₂O的清液体系中,于423K晶化6h的条件下可较快地形成一层厚度为5μm的连续致密纯相T型分子筛膜,较大缩短了膜合成时间且提高了膜致密性.在优化条件下所合成的膜具有优良的分离性能和高重复性.348K时,在10wt%水-90wt%异丙醇混合物体系中膜的渗透通量和分离因子分别高达4.20kg/(m²·h)和7800.     

Electroless Pd and Ag deposition kinetics of the composite Pd and Pd/Ag membranes synthesized from agitated plating baths

The atomic absorption spectroscopy (AAS) has been successfully utilized for the measurement of the Pd and Ag ion concentrations in the plating baths and to elucidate the effects of temperature, initial metal ion and reducing agent concentrations and agitation on the electroless plating kinetics of Pd and Ag metals. The initial metal ion concentrations for Pd and Ag were varied over a range of 8.2–24.5 mM and 3.1–12.5 mM, respectively. The plating reactions were conducted in a constant temperature electroless plating bath over a temperature range of 20–60 °C and an initial hydrazine concentration range of 1.8–5.4 mM. It was found that the electroless plating of both Pd and Ag were strongly affected by the external mass transfer in the absence of bath agitation. The external mass transfer limitations for both Pd and Ag deposition have been minimized at or above an agitation rate of 400 rpm, resulting in a maximum conversion of the plating reaction at 60 °C and dramatically shortened plating times with the added advantage of uniform deposition morphology. The derivation of the differential rate laws and the estimation of the reaction orders and the activation energies for the electroless Pd and Ag kinetics were conducted via non-linear regression analysis based on the method of initial rates. For a constant-volume batch reactor, the integrated rate law was solved to calculate the conversion and the reactant concentrations as a function of plating time. The model fits were in good agreement with the experimental data. Furthermore, the bath agitation and the plating conditions used in the kinetics study were adopted for the synthesis of 16–20 μm thick composite Pd/Ag membranes (10–12 wt% Ag) and a pure-Pd membrane with a hydrogen selective dense Pd layer as thin as 4.7 μm. While hydrogen permeance of the Pd/Ag membranes A and B at 450 °C were 28 and 32 m³/m²-h-atm^0.5, the H₂ permeance for the 4.7 μm thick pure-Pd membrane at 400 °C was as high as 63 m³/m²-h-atm^0.5_. The long-term permeance testing of all the membranes synthesized from agitated plating baths resulted in a relatively slow leak growth due primarily to the improved morphology obtained via the bath agitation and modified plating conditions.     

A New Approach on the Active Treatment for Electroless Copper Plating on Glass

A new method is described for the electroless deposition of copper onto glass.Commercially available glass slide was modified with γ-aminopropyltrimethoxysilane to form self-assembled monolayer (SAM) on it .Then it was dipped directly into PdCl2 solution instead of the conventional SnCl2 sensitization followed by PdCl2 activation.Experimental results showed that the Pd^2 ions from PdCl2 solution were coordinated to the amino groups on the glass surface resulting in the formation of N-Pd complex.In an electroless copper bath containin a formaldehyde reducing agent,the N-Pd complexes were reduced to Pd^0 atoms,which then acted as catalysts and initiated the deposition of copper metal.Although the copper deposition rate on SAM-modified glass was slow at the beginning,it reached to that of conventional method in about 5min.     

Electrodeposition of Fe70Pd30 nanowires from a complexed ammonium–sulfosalicylic electrolyte with high stability

A highly stable plating bath for the electrodeposition of Fe–Pd nanowires into nanoporous alumina templates has been developed. Complexing of both metal ions and exchanging Fe²⁺ by Fe³⁺ avoid chemical reduction of Pd ions and, therefore, undesirable deposition. By using a pulse potential mode and appropriate adjustment of deposition potentials homogeneously filled templates without surface deposits and nanowires close to the desired composition of Fe₇₀Pd₃₀ have been achieved. These alloy nanowires represent a key step towards nanoactuators based on magnetic shape memory alloys.     

Preparation of palladium composite membranes by modified electroless plating procedure

A thin palladium composite membrane was produced by modified electroless plating procedure. Compared with the conventional electroless plating procedure, the modified electroless plating procedure consists of the activation of a ceramic substrate by the sol–gel process of a Pd(II)-modified boehmite sol. Additionally, the infiltration of an electroless plating solution to a porous substrate during the deposition of palladium was employed with the filter device to improve adherence of a palladium layer to a substrate. The resulting membrane with a thickness of about 1 μm has a high compactness. The membrane shows a hydrogen selectivity of 20–130 for H₂/N₂, and a hydrogen flux of 1.8–87 m³/m²·h, depending on operation conditions.     

Discrete Silver(I)‐Palladium(II)‐Oxo Nanoclusters, {Ag4Pd13} and {Ag5Pd15}, and the Role of Metal–Metal Bonding Induced by Cation Confinement

We introduce the class of discrete silver(I)‐palladium(II)‐oxo nanoclusters with the preparation of {Ag₄Pd₁₃} and {Ag₅Pd₁₅}. Both polyanions represent the first examples of noble metal‐capped polyoxo‐noble‐metalates in a fully inorganic assembly, featuring an unprecedented host–guest mode containing hetero‐ and homometallic Ag–Pd and Ag–Ag bonding interactions. Comprehensive theoretical calculations suggest that the Ag–Pd metallic bonds originate partially from surface confinement of Ag^I guest ions onto the anionic polyoxopalladate host that is induced by strong electrostatic forces. This work opens the field of fully inorganic silver‐palladium‐oxo nanoclusters, which can be considered as discrete mixed noble metal precursors for the formation of monodisperse core–shell nanoparticles, with high relevance for catalysis.     

The formation and behavior of Ag adsorbates at Pd electrodes and their influence on electrocatalytic oxidation of formic acid at Pd

The electrochemical behavior of Ag ions at smooth Pd electrodes and Pd/Pt deposits is investigated. At adsorption potentials, which are more anodic than the reversible potential of the Ag⁺/Ag electrode, an underpotential deposition of Ag⁺ ions occur.We can distinguished two types of Ag ad-atoms at Pd. The first type of Ag is irreversibly adsorbed. The second, which exists only in the presence of Ag ions in the solution, is reversibly adsorbed.The influenced of various coverages of Ag ad-atoms at smooth Pd and Pd/Pt deposits on the electrocatalytical oxidation of formic acid was investigated. Even small coverages of Ag ad-atoms lower the rate of formic acid oxidation. With higher coverages this inhibiting influence grows continously.     

Simultaneous separation and extraction of Ag(I), Pb(II) and Pd(II) ions by solid phase method and determination of these ions by flame atomic absorption spectrometry

A simultaneous preconcentration and separation method for determination of trace amount of dissolved Ag⁺, Pb²⁺ and Pd²⁺ ions by modified octadecyl silica membrane disks with DBzDA18C6 was developed. The adsorbed metal complexes were eluted from disk with 10?mL of 4?M KCl and determined by flame atomic absorption spectroscopy. Several parameters such as anion effect, pH of sample solution, type of eluent, amount of ligand, sample and elution flow rate were evaluated. The effect of diverse ions on preconcentration was also investigated. A precocentration factor of 110 can easily be achieved depending on the volume of the sample. For 100?mL of the solution the linear dynamic rang were found to be 30–1000, 140–6000, 60–900?μg?l^?1 for Ag⁺, Pb²⁺ and Pd²⁺, respectively. Based on three standard deviation of the blank the detection limit was obtained as 1.8, 8.0 and 4.2?μg?L^?1 for Ag⁺, Pb²⁺, Pd²⁺, respectively. The formation constants of Ag⁺ and Pb²⁺ ions with DBzDA18C6 at 25?°C were determined from the molar conductance–mole ratio data. This method was applied for the determination of Ag⁺, Pb²⁺ and Pd²⁺ in environmental water, tea and soil samples.     

Ag活化的p型硅(111)表面化学镀Ag膜表面形貌研究

A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3＋NH3＋acetic acid＋NH2NH2 （pH 10.2）. The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film.     

Monolayer deposition of silver and copper onto platinum electrodes at non-equilibrium conditions

Ag and Cu were deposited in submonolayer amounts onto Pt electrodes at constant cathodic potentials within the hydrogen adsorption region. Rectangular pulses of Cu²⁺ or Ag⁺ fluxes to the Pt surface were generated by a Cu or Ag generator electrode using the twin electrode thin-layer technique. The analysis of the response currents of the Pt electrode yields in formation about the metal deposition process at non-equilibrium conditions. Cu and Ag were found to deposit directly as monolayers and not at random. The displacement of adsorbed hydrogen was measured as a function of the quantity of metal deposited.     

冠醚聚合物的研究 Ⅱ.以聚硫醚为主链的硫杂冠醚聚合物的合成及其络合性能

 本文报道了一种合成硫杂冠醚聚合物的新方法。以聚(2′-氯乙基-2,3-环硫丙基醚)为预聚物与二巯基化合物通过大分子反应直接环化,一步法合成了四种以聚硫醚为主链的新型硫杂冠醚聚合物(PD1-PD4)。并测定了它们对Ag⁺、Au³⁺)、Pd²⁺、Pt⁴⁺、Cu²⁺、Hg²⁺、Zn²⁺、Cd²⁺、Pb²⁺、Mg²⁺、K⁺、Ns⁺等金属离子的络合性能。结果表明:它们除不络合K⁺、Na⁺、Mg²⁺、Pb²⁺外,对其它八种离子有不同程度的络合,其中对Ag⁺、Au³⁺、Pd²⁺等贵金属离子的络合容量较高。