铜表面修饰硅烷膜在碱性溶液中的耐蚀性能研究

为了提高铜的耐蚀性,用自组装技术在铜表面上制备了3-巯基丙基三甲氧基硅烷(MPTS)自组装膜. 利用红外光谱和扫描电子显微镜研究了该膜的结构,运用极化曲线和交流阻抗图谱等电化学方法考察了 MPTS膜在0.5 mol/L NaOH溶液中对铜电极的缓蚀性能.结果表明,MPTS在铜表面可能以化学吸附方式强烈吸附到铜表面, 同时在表面以Si-O-Si键自我交联形成了线性低聚物, MPTS浓度越高, 其膜更致密.与裸铜电极相比,经MPTS修饰后的铜的腐蚀电位正移200 mV, 腐蚀电流降低一个数量级,其缓蚀效率为86.5%.     

Reflection and Absorption Techniques for Optical Characterization of Chemically Assembled Nanomaterials

This review discusses recent developments in the areas of fabrication, certain types of optical characterization, and applications of a selected class of chemically assembled nanomaterials, namely i) gold and silver nanoparticles deposited onto optically transparent glass substrates; ii) thiol‐functionalized self‐assembled monolayers (SAMs); iii) chemically stabilized gold and silver nanoparticles (monolayer protected clusters, MPCs); and iv) MPCs linked to metallic substrates and adsorbates. Six linear optical techniques for the characterization of these materials are discussed: transmission localized surface plasmon resonance spectroscopy, T‐LSPR; propagating surface plasmon resonance spectroscopy, P‐SPR; polarization‐selective Fourier transform infrared reflection absorption spectroscopy, PS‐FTIRRAS; polarization‐modulation Fourier transform infrared reflection absorption spectroscopy, PM‐FTIRRAS; surface‐enhanced infrared reflection absorption spectroscopy, SEIRRAS; and infrared ellipsometry. The review focuses particularly on providing a unified treatment of these six optical techniques by using a relatively simple stratified multilayer model.     

Studies on corrosion inhibition of copper by alkanethiol SAMs prepared in aqueous micellar solution

The character of 1‐dodecanethiol (DT) self‐assembled monolayers (SAMs) formed on copper surface in aqueous micellar solution is investigated by means of contact angle measurement, electrochemical impedance spectroscopy (EIS), and polarization curves. The contact angle measurement shows that the SAMs formed in aqueous micellar solution are oriented and compact. According to the electrochemical measurements, it is found that both the concentration of DT and temperature can significantly affect the property of SAMs. The DT SAMs can prevent the corrosion of copper in chloride‐containing solution effectively because the inhibition efficiency can reach 99.59% at the DT concentration of 10^?2 M . The adsorption of DT in aqueous micellar solution obeys to the Langmuir adsorption isotherm, and the value of the free energy of adsorption calculated indicates that the adsorption of DT molecule is a spontaneous process and a typical of chemical adsorption.     

Determination of heavy metal ions in mixed solution by imprinted SAMs

Specific selectivity toward different heavy metal ions could be introduced into self-assembled monolayers (SAMs) by ion imprinting. In the mixed solution, good response toward mercury ions could be obtained on mercury ions imprinted SAMs, the copper ions imprinted SAMs presented good selectivity toward copper ions, while on lead ions imprinted SAMs, significantly higher insertion of lead ions than mercury and copper ions were observed. Linear calibration plots were obtained for each heavy metal ion and the regression equations were: [Hg(II)]/(10⁻⁶ M), [Cu(II)]/(10⁻⁶ M) and [Pb(II)]/(10⁻⁶ M) for mercury, copper and lead ions, respectively. The detection limits were determined to be: 1.46×10⁻⁸ M for Hg(II), 3.73×10⁻⁸ M for Cu(II) and 4.34×10⁻⁸ M Pb(II). The decreases in current response for mercury, copper and lead ions in the presence of 100-fold interferential ions were: 3.37%, 9.16% and 7.60%, respectively. Acceptable recoveries were obtained in mixed solutions at both high and low concentrations.     

Fabrication of a stable, switchable An/SAM-Au electrode with tunable electron transfer and excellent electrochemical properties

This paper describes the electrochemical properties, such as electrode reactivity, and interfacial capacitance of an anthracene/self-assembled monolayer (An/SAM) Au electrode prepared through controllable immersion of the dodecanethiol (C₁₂SH) SAM-Au electrode in a THF solution of anthracene (An). The C₁₂SH SAM almost totally blocks heterogeneous electron transfer between the bare Au electrode and Fe(CN)₆^3−/4− in solution, but adsorption of the An molecules onto the SAM-Au electrode restores electron transfer. The prepared An/SAM-Au electrode possesses good reactivity without a remarkable barrier to heterogeneous electron transfer. On the other hand, the electroactive form of the An/SAM-Au electrode can be converted back to the non-electroactive form by immersing the electrode into pure THF.     

Immobilization of β-cyclodextrin on gold surfaces by chemical derivatization of an 11-amino-1-undecanthiol self-assembled monolayer

A new methodology for the covalent functionalization of a SAM of 11-amino-1-undecanethiol, previously adsorbed on polycrystalline Au, was successfully applied in order to immobilize a β-CD layer on surface. A two steps synthetic strategy is proposed based on the activation of the SAM with di-(N-succinimidyl) carbonate for the further inclusion of the β-CD. The modification of the SAM was followed by PM-FTIRRAS, AFM imaging, CV, and EIS which confirmed the introduction of β-CD layer. The AFM images allowed the identification of homogeneously distributed β-CD aggregates over the Au grain microstructure. The electrode was characterized in the presence of electroactive species in solution, with the ability to form inclusion complexes with the β-CD cavity. Contrary to the reported for other thiolated CD derivative films, the results of this study showed the formation of well-packed and compact structures which strongly reduce non-specific adsorption phenomena. The redox response of the probes at the β-CD electrode was shown to appear at higher potentials with respect to the response at bare Au. Good correlation was found between the increase of the hydroquinone oxidation peak and, both, the scan rate used in CV experiments (typical behavior of surface-confined species) and the hydroquinone concentration. In the case of dopamine, the processes seem to shifted out of the potential window of SAM stability. The results suggest that this problem could be overcome by improving the design of the device.     

Scanning tunnelling microscopy imaging of [3 × 3] Mn nonanuclear grids

The scanning tunnelling microscopy imaging of [3 × 3] Mn(II) nonanuclear grids on gold substrates is described. Self‐assembled behaviour is observed at both high and low coverage, with submolecular resolution of individual molecules displayed at low deposition concentrations. The importance of proper image processing techniques is demonstrated in resolving the layer structure at high coverage.     

Molecular-level design of binary self-assembled monolayers on polycrystalline gold electrodes

In this study, we followed up, by measuring the reductive desorption patterns, the time-dependent growth of the self-assembled monolayer (SAM) of a thiol compound (typically cysteine) formed on polycrystalline Au (poly-Au) electrode. Cysteine molecules appeared to adsorb preferentially and consecutively at the Au(1 1 0), Au(1 0 0) and then at the Au(1 1 1) surface domains of the poly-Au. A 95% surface coverage of cysteine (Γ_cysteine) was attained after 5 s, 120 s and more than 300 s for the Au(1 1 0), Au(1 0 0) and Au(1 1 1) domains, respectively, of the poly-Au electrode. The electrochemical reduction of molecular oxygen (O₂) in O₂-saturated 0.5 M KOH was utilized as a probing reaction for the extent of the compactness of the SAM. A binary SAM of two thiols (cysteine and cystamine) has been successfully designed over the poly-Au electrode at which a precise positioning of cysteine was achieved, i.e., cysteine was attached to the Au(1 1 1) domains, while cystamine to the Au(1 0 0) and Au(1 1 0) domains. SEM images for the electrodeposited Ag over the cysteine sub-SAM/Au electrode gave a possible mapping of the Au(1 1 1) domains of the poly-Au electrode.     

硅基双层复合自组装分子膜结构特性及其润湿行为的分子动力学模拟

用分子动力学方法模拟了单晶硅（Si）表面N-3-（三甲氧基硅烷基）丙基乙二胺（DA）-月桂酰氯（LA）（DA-LA）双层复合自组装分子膜（SAMs）的结构特性,得到膜层中DA和LA分子的最佳覆盖率及分布情况。进一步讨论了水滴在DA-LA双层复合SAMs表面的润湿过程,通过接触角和径向分布函数等参量对其润湿行为进行了分析。研究表明：DA分子在Si上覆盖率为50%、LA分子在DA自组装单分子膜（DA SAM）上接枝率为100%时,分子膜呈有序排布,体系能量最低,从分子角度揭示了Si表面覆盖致密SAMs的形成机制。当取最佳覆盖率体系进行润湿机制模拟时,DA-LA双层复合SAMs表面水滴接触角与实验值相似,表现出良好的疏水性。而DA SAM表面由于DA分子短而稀疏,暴露出底层更亲水的羟基分子,从而导致所得接触角较实验偏小;经测量及计算得出,羟基化Si表面自由能最高,表现出较强的亲水性;DA表面次之;DA-LA表面自由能最低,表现出良好的疏水性。进一步分析发现：羟基化Si表面、DA SAM表面与水滴间存在氢键,加强了表面的亲水性,而DA-LA双层复合SAMs表面与水滴间只存在弱范德华力,有利于表面呈现疏水性。