Solid electrolyte interphase (SEI) electrode: Part III. Deposition-dissolution process of lithium in thionyl-chloride solution

The deposition-dissolution mechanism of lithium on stainless steel and calcium electrodes in 1 M LiAlCl₄ -thionyl-chloride solution is studied by pulse galvanostatic and ac techniques. The metal -solution interfacial capacitance of the stainless steel electrode is about 30 μF cm^?2 which is higher by an order of magnitude than the capacitance of lithium-coated stainless steel and either pure or lithium-coated calcium. The lower capacitance is attributed to the existence of a solid electrolyte interphase (SEI) on the coated stainless steel or the calcium electrode.Significantly different is observed upon deposition of lithium on stainless steel or calcium. Deposition on stainless steel takes place only after prior formation of a SEI on the electrode (by passage of about 20 mC cm^?2), while deposition on calcium starts immediately after the electrode capacitance has been charged (by about 5 μC cm^?2). Furthermore, deposition of about 3% of a monolayer of lithium on calcium is enough to stabilize its potential at 0.0 V vs. LiRE.On the lithium-coated stainless steel electrode, a linear relationship between the current and over-potential is observed for up to 700 mV. This indicates a Tafel slope > V. During lithium deposition on stainless steel, the SEI resistivity is about 1.5 × 10⁷ Ω-cm and its thickness is about 10 nm.Under open circuit potential, the deposited lithium corrodes at an apparent rate of 100 μA cm^?2. Rapid fluctuations of the electrode potential during the corrosion or dissolution process are accounted for by a break and repair mechanism of metallic contact between lithium deposited within the SEI and the current collector.     

基于Pt/Au双金属修饰针灸针的非酶葡萄糖传感器

通过在不锈钢针灸针（AN）表面依次电沉积金（Au）纳米颗粒和铂（Pt）纳米颗粒,基于它们在AN表面的协同作用,实现了一种用于非酶葡萄糖检测的电化学生物传感器。首先,通过扫描电子显微镜对其功能界面（Pt/Au/AN）进行表征,结果显示类似卷心菜的纳米材料均匀致密地分布在AN表面。然后,通过循环伏安法和电化学阻抗法对Pt/Au/AN电极的电化学特性进行了研究。结果表明,与Au/AN或Pt/AN电极相比,Pt/Au/AN电极对葡萄糖氧化表现出优越的电催化活性。这表明双金属Pt/Au的接触界面是葡萄糖氧化的重要电催化位点。在pH7.4的模拟生理介质中,制得传感器的线性范围为0.1~35 mmol·L^-1,检测限为0.0763 mmol·L^-1,对葡萄糖的检测表现出较高的灵敏度和良好的抗干扰性能、稳定性。此外,该传感器已成功用于人体血清葡萄糖的检测。     

天然海水中聚吡咯膜的防微生物附着及防腐蚀性能

采用恒电流法在316 L不锈钢电极表面合成聚吡咯(PPy), 通过开路电位、 生物显微镜(BM)、 Tafel极化曲线及电化学交流阻抗(EIS)研究了聚吡咯防止微生物附着及防腐蚀特性. 研究表明, 沉积聚吡咯的316 L不锈钢电极浸泡在天然海水中(0~20 d), 开路电位基本保持不变, 表明电化学合成的聚吡咯膜有良好的防止微生物附着能力, 并通过生物显微镜进行了验证, 且在浸泡的过程中其腐蚀电流密度维持在10^-7 mA/cm², 表现出良好的防腐蚀特性; 浸泡50 d后, 其防腐蚀效率仍高达97.45%. 因此, 电化学合成的聚吡咯具有优异的防止微生物附着和防腐蚀特性.     

海洋微生物对316不锈钢的电化学腐蚀行为

采用自腐蚀电位、电化学极化曲线、电化学阻抗谱技术研究了316不锈钢在无菌培养基介质和海水微生物接种培养有菌培养基介质中不同周期的腐蚀行为．结果表明,316不锈钢电极在有菌介质中比在无菌介质中的腐蚀电流密度大,腐蚀电位负移,微生物加速了不锈钢的腐蚀速度．随着浸泡时间的增加,有菌介质中的不锈钢电极极化电阻值逐渐减小,表明了海洋微生物的附着和繁殖加速了316不锈钢的腐蚀速率,降低了其在海洋环境中的耐蚀性．     

锆离子改善十烷基磷酸组装膜结构及性能研究

利用烷基磷酸、金属锆离子和不锈钢电极表面的相互作用,通过表面自组装,在304不锈钢电极表面分别修饰了单层和双层烷基磷酸自组装膜,采用接触角和极化曲线对修饰电极进行测量.实验表明,双层烷基磷酸修饰膜具有更佳的耐腐蚀性能.     

溶胶-凝胶法制备改性TiO2纳米薄膜及其防腐蚀性能

应用溶胶-凝胶法和浸渍提拉技术在316L不锈钢表面分别制备TiO2纳米膜和 B-Fe-Ce改性的TiO2纳米膜. 采用场发射扫描电子显微镜(FE-SEM)、原子力显微镜(AFM)、拉曼光谱法和能量分散谱(EDS)对薄膜进行表征,通过电化学阻抗谱(EIS)和动电位阳极极化曲线的测试考察薄膜的耐蚀性及对不锈钢的保护性能. 结果表明:两种纳米薄膜均含锐钛矿型的TiO2纳米颗粒,纯TiO2纳米膜与改性后的纳米膜中颗粒直径分别约为15和10 nm. TiO2/316L不锈钢和 B-Fe-Ce-TiO2/316L不锈钢膜电极浸泡在0.5 mo.lL-1 NaCl溶液后,后者的电化学反应电阻较大,动电位阳极极化曲线的稳定钝化区较宽,击穿电位更高,说明改性的纳米膜的耐蚀性及其保护性能更好.     

Miniaturized reference electrodes with stainless steel internal reference elements

Stable reference electrodes have previously been obtained by immersion of a stainless steel internal reference element (SSIRE) in a solution of steady pH, e.g., a stainless steel wire maintained in 2 mol/l HCl. Here, we report the miniaturization of this regular size reference half-cell by embedding thermally activated SSIREs in a copolymer matrix of a fixed and constant pH value. The resulting electrode is based on a polymer volume of 1-5 μl, while its contact area at the polymer/analyte solution interface is 0.4 mm². Photopolymerized acrylic type hydrogel is used as the copolymer which contains a quaternary ammonium salt as the supporting electrolyte. These miniaturized reference electrodes show potential stability over the pH range of 1-13, maintain a constant potential value over the time, and are suitable for potentiometric and voltammetric measurements in both aqueous and organic media. Furthermore, they do not exhibit leakage problems. Hence, they do not contaminate the analytical sample, even when the reference electrodes (REs) are used in very small volumes and over extended period.     

Influence of the semiconducting properties of a current collector on the electric double layer formation on porous carbon

The electrochemical behavior of polyacrylonitrile-based activated carbon cloth combined with a stainless steel current collector was examined using ac impedance spectroscopy. H(2)SO(4), KOH, and KNO(3) were employed as the electrolytes. The data presented in the impedance complex plane exhibit a semicircle at high frequencies followed by a vertical line at low frequencies. The high frequency data were found to be characteristic of the space charge region of the semiconducting oxide layer on the stainless steel, while the low frequency data depicted the double layer formation on the porous carbon. The double layer capacitance was found to decrease with the space charge resistance, which was potential dependent and a major contribution to the overall resistance of the carbon/stainless steel electrode. The electrolyte type affected the potential window employed in energy storage and thus the semiconducting behavior of the oxide layer. Both the n- and p-type semiconductors in depletion condition appeared within the potential window applied for the H(2)SO(4) electrolyte, and this caused the presence of a peak capacitance. Only the n-type depletion condition was found in the KNO(3) and KOH electrolytes with the p-type oxide situated in accumulation at the potentials applied, and thus, the capacitance was larger at more negative potentials.     

无机-有机杂化聚合物电解质的制备与电化学性能

以有机改性聚硅氧烷为单体加入液态电解质通过紫外光辐射固化制备了无机有机杂化聚合物电解质.含有丙烯酸酯端基的有机改性聚硅氧烷单体是通过正硅酸甲酯(TMOS)的水解缩合反应产物与丙烯酸2羟乙酯(HEA)进行脱甲醇反应合成的.它是一种多官能团单体,其结构通过核磁共振氢谱(1HNMR)分析、红外光谱(FTIR)分析及二氧化硅分析进行了表征,分子式可表达为SiO1.143(OH)0.016(OCH3)1.339(OCH2CH2OCOCHCH2)0.357.无机有机杂化聚合物电解质的电化学性能通过交流阻抗和循环伏安法进行了表征.其离子电导率随着液态电解质含量的增大而提高,当液态电解质含量为85wt%时,电导率在22℃为5.5×10-3Scm-1,在-23℃也能达到1.1×10-3Scm-1.界面电阻经过开始2天的增大后达到稳定,电化学稳定窗口超过5.0V,不锈钢电极上锂的电化学沉积与剥离循环可逆性很高.     

Effect of thermal annealing of poly(3-octylthiophene) films covered stainless steel on corrosion properties

The effect of thermal annealing of poly(3-octylthiophene) (P3OT) coatings on the corrosion inhibition of stainless steel in an NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride (FeCl₃) as oxidant. P3OT films were deposited by drop-casting technique onto 304 stainless steel electrode (304SS). 304SS coated with P3OT films were thermally annealed during 30 h at different temperatures (55°C, 80°C, and 100°C). The corrosion resistance of stainless steel coated with P3OT in 0.5 M NaCl aqueous solution at room temperature was investigated by using potentiodynamic polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. The results indicated that the thermal treatment at 80°C and 100°C of P3OT films improved the corrosion resistance of the stainless steel in NaCl solution; the speed of corrosion diminished in an order of magnitude with regard to the 304SS. In order to study the temperature effect in the morphology of the coatings before and after the corrosive environment and correlate it with corrosion protection, atomic force microscopy and scanning electron microscopy were used. Morphological study showed that when the films are heated, the grain size increased and a denser surface was obtained, which benefited the barrier properties of the film.     

Combination of electrografting and atom-transfer radical polymerization for making the stainless steel surface antibacterial and protein antiadhesive

A two-step "grafting from" method has been successfully carried out, which is based on the electrografting of polyacrylate chains containing an initiator for the atom transfer radical polymerization (ATRP) of 2-(tert-butylamino)ethyl methacrylate (TBAEMA) or copolymerization of TBAEMA with either monomethyl ether of poly(ethylene oxide) methacrylate (PEOMA) or acrylic acid (AA) or styrene. The chemisorption of this type of polymer brushes onto stainless steel surfaces has potential in orthopaedic surgery. These films have been characterized by ATR-FTIR, Raman spectroscopy, atomic force microscopy (AFM), and measurement of contact angles of water. The polymer formed in solution by ATRP and that one detached on purpose from the surface have been analyzed by size exclusion chromathography (SEC) and (1)H NMR spectroscopy. The strong adherence of the films onto stainless steel has been assessed by peeling tests. AFM analysis has shown that addition of hydrophilic comonomers to the grafted chains decreases the surface roughness. According to dynamic quartz crystal microbalance experiments, proteins (e.g., fibrinogen) are more effectively repelled whenever copolymer brushes contain neutral hydrophilic (PEOMA) co-units rather than negatively charged groups (PAA salt). Moreover, a 2- to 3-fold decrease in the fibrinogen adsorption is observed when TBAEMA is copolymerized with either PEOMA or AA rather than homopolymerized or copolymerized with styrene. Compared to the bare stainless steel surface, brushes of polyTBAEMA, poly(TBAEMA-co-PEOMA) and poly(TBAEMA-co-AA) decrease the bacteria adhesion by 3 to 4 orders of magnitude as revealed by Gram-positive bacteria S. aureus adhesion tests.     

Evaluation of quantitative recovery methods for Listeria monocytogenes applied to stainless steel

The ability of Listeria monocytogenes to attach to various food contact surfaces, such as stainless steel, polypropylene, and rubber compounds, is well documented. The retention of these or other pathogenic bacteria on food contact surfaces increases the risk of transmission to food products. The objective of this study was to compare several methods for quantitative recovery of Listeria monocytogenes from stainless steel surfaces. A cocktail of 4 serotypes of Listeria monocytogenes mixed in equivalent concentrations was inoculated onto type 304 stainless steel coupons in a 2 x 2 cm area. After 1 h exposure, coupons were sampled by one of the following methods: (1) swabbing with a premoistened Dacron swab; (2) rinsing with phosphate-buffered saline; (3) direct contact onto tryptic soy agar containing 0.6% yeast extract (TSA + YE) plates for 10 s; (4) sonication in an ultrasonic water bath (40 kHz); (5) contact with the bristles of a sonicating brush head for 1 min; and (6) indirect contact (2-4 mm distance) with a sonicating brush head for 1 min. The 3 sonication methods yielded higher recovery than the other 3 methods (P < 0.05). Brushing the coupons with the sonicating brush head (contact or noncontact) yielded a recovery level of about 60%. The lowest cell recovery (about 20%) was observed with the swab and direct agar contact methods. After a 12 h exposure, recoveries ranged from 17.4 (brush contact method) to 2% (swab method).     

Electrochemical behavior of stainless steel in aerated NaCl solutions by electrochemical impedance and rotating disk electrode methods

Electrochemical behavior of stainless steel in 0.5 M NaCl solutions is studied. It is shown that, for this steel, under a considerable cathodic polarization of electrode, the oxygen electroreduction proceeds via a four-electron mechanism. The corrosion current is estimated. From the impedance spectra, elements of an equivalent circuit that describes the electrode behavior under the ac conditions are calculated. A mechanism of the steel passivation in the electrolyte is proposed.     

模拟冷却水中不锈钢的自钝化及硫离子的影响

通过对316＃不锈钢/模拟冷却水体系电化学阻抗谱(EIS)的测定和拟合，确定了合适的模型.根据此模型，膜电阻R2在电极浸泡过程中增大， 反映膜电容的Y02值则不断减小，显示钝化膜的增厚和致密.模拟冷却水中硫离子的加入使R2迅速降低.Mott-Schottky图测定显示，在模拟冷却水中浸泡65天的不锈钢钝化膜的施主密度ND和受主密度NA分别为1.47×1020和2.20×1020 cm－3，加入9 mg•L－1硫离子1 h后， ND和NA分别上升到4.52×1020和7.02×1020 cm－3.极化曲线测定表明9 mg•L－1硫离子使不锈钢钝态电流增大了近一倍.     

不锈钢网阴极微生物燃料电池的产电性能研究

构建了一个以曝气池污泥为阳极接种微生物、碳毡为阳极、无任何修饰的不锈钢网为阴极的双室微生物燃料电池. 通过输出电压、功率密度以及电化学阻抗等考察了阴极面积对电池产电性能的影响,并对电池的长期运行稳定性进行评价. 研究结果表明,不锈钢网作为微生物燃料电池的阴极性能稳定. 当不锈钢网面积为2 × 2 cm²时,最大输出电压达到0.411 V,功率密度为0.303 W•m^-2,内阻841 Ω,极化内阻80 Ω. 增大阴极面积至2 × 4 cm²,最大输出电压能达到0.499 V,内阻减小至793 Ω. 不锈钢网价格便宜,具有长期运行稳定性,适宜做MFCs的阴极.     

Characterization of the Outer Layer Nanostructure in the Electrochemical Response of Stainless Steel in Aqueous Sodium Hydroxide

The outer layer nanostructure of stainless steel’s passive film in 0.1?M NaOH has been studied by electrochemical atomic force microscopy and the role of the outer layer in the electrochemical response of stainless steel has been characterized. The outer layer is mainly composed of nanoscale particles whose average diameter is up to 13.14?±?3.52?nm at the end of the formation period. The formation process is characterized by the nucleation, growth, and contact of oxide particles. Based on the study on the outer layer nanostructure, the gaps/boundaries between particles in the outer layer should be diffusion paths for ions across the layer. The electrochemical impedance spectroscopy analysis revealed that the ion diffusion resistance first increased and then remained stable due to the three-dimensional growth of nanoscale particles.     

水热氧化改性碳纸电极在全钒氧化还原电池中的应用

为了提高钒氧化还原电池电极的活性,在180°C下将碳纸电极与过氧化氢的硫酸溶液置于有聚四氟乙烯内衬的不锈钢反应釜中进行不同时间的水热酸氧化处理.水的接触角测试表明,随着处理时间从6h调整至18h,处理前后碳纸电极的接触角也从120.0°降低至100.8°,尤其是经过12h处理的样品的接触角最小,这说明在此条件下处理过的碳纸的亲水性得到了提高.而傅里叶变换红外测试表明,羰基和羧基等含氧基团被成功地引入到了碳纸电极中.使用扫描电镜,循环伏安,电化学阻抗以及充放电技术分别检测了处理前后样品的表面形貌及电化学性能.V(IV)/V(V)氧化还原电对在这些处理过的样品上表现出较大的活性.用处理12h的碳纸电极组装的单电池性能优异,在30mA·cm-2的电流密度下能量效率达到了80%,相应的电流效率和电压效率分别为96%和84%.     

聚吡咯/聚苯胺复合型导电聚合物防腐蚀性能

采用循环伏安法,在含吡咯和苯胺的0.3 mol/L草酸水溶液中制备了聚吡咯/聚苯胺(PPy/Pani)的复合型导电聚合膜。采用红外光谱、极化曲线、自腐蚀电位-时间曲线、扫描电子显微镜和电化学阻抗谱研究了共聚膜的防腐蚀性能。结果表明,在1 mol/L H2SO4中,PPy、Pani与不锈钢基体发生氧化还原反应,促进不锈钢表面发生钝化;当苯胺与吡咯浓度比为1∶3时,制备得到的复合型导电聚合膜所保护的不锈钢自腐蚀电流最小,自腐蚀电位最高,保护时间最长。PPy、Pani及其共聚膜在3.5%NaCl溶液中电化学阻抗谱表明,所制备的PPy、Pani及其共聚物膜与不锈钢基体发生氧化还原反应,使其表面钝化;当Cl-到达不锈钢表面时,破坏钝化膜导致不锈钢腐蚀。     

An Electrochemical Study on the Corrosion Inhibition of Stainless Steel by Polyaniline Film

Polyaniline(PANI)film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte.The potential sweep rates were changed to achieve the PANI film with different thickness and structures.Protective properties of the PANI film for corrosion of stainless steel in 3% NaC1 aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance,reflecting higher inhibition for corrosion of the stainless steel.