超声法制备纳米气泡及其对电极表面双电层影响的研究

发布时间：2018-09-03 07:58

【摘要】：近些年来,界面上的有关问题越来越成为研究者们研究的难点和热点。在固液界面上存在纳米气泡最初来源于人们研究表面疏水长程引力的作用机制。在经典热力学理论中,室温下水中纳米气泡被认为是不能稳定存在的。近些年来对疏水表面的深入研究,许多现象都表明固液界面有纳米气泡的存在,纳米气泡的存在已经通过中子衍射技术,原子力显微镜等方法得到了证实,最重要的是利用原子力显微镜的方法对纳米气泡成像研究,有利地证实了纳米气泡的存在。当前,直接探测固液界面纳米气泡的最有力手段是原子力显微镜(AFM)。在用AFM对纳米气泡成像时,通常选用表面较为平整的基底。主要有高序热解石墨(HOPG),云母,金,聚苯乙烯薄膜等。到目前为止,关于纳米气泡的生成方法已经得到了广泛的研究,例如醇水替换法,不同溶液替换法,直接滴加法,直接浸渍法,快速加热法,电化学法等。其中,替换法是近年来研究的最多的一种方法。醇水替换法是一种可高度可重复性,并且可以在不同的基底上生成大量纳米气泡的方法而被广泛研究。但是,有一些可溶于有机物的基底不能用有机溶剂,并且由于使用有机溶剂,很容易引入杂质。因此,为克服这些缺点,需要找到一些新的纳米气泡的制备方法。超声法让我们有了新的思路。我们通过超声产生纳米气泡和电化学工作站结合,对玻碳电极进行循环伏安曲线测试,在此实验中,我们将脱气电解质溶液和未脱气电解质溶液分别用于实验中,对比两个实验结果从而来得出纳米气泡的生成。我们还研究了超声时间对纳米气泡生成的影响,实验得出,超声时间越长,双电层电容在不断地下降,直到变化平稳,从而根据推导得出纳米气泡随着超声时间的增加对电极的覆盖面积越来越大。超声次数的影响,随着超声次数的增加,双电层电容也在不断地减小,直到变化平稳,根据双电层电容的理论推导和实验结果相结合,我们得出,超声次数的增加相对介电常数在减小,所以纳米气泡在不断地覆盖电极表面。超声波频率的大小对纳米气泡的生成也有很大关系,随着超声波频率的增大,电容在不断下降,纳米气泡在不断地增多增大,覆盖的点击面积在不断的变大。除此之外,我们还用传统的醇水替换法在玻碳电极表面产生纳米气泡,然后用电化学工作站来测试对电极的影响。通过用醇水替换法测得替换前和替换后电容,比较后发现替换后电容变小,根据理论推导与实验结果得出,醇水替换后在玻碳电极上产生了纳米气泡。我们又用脱气的醇,脱气的水和脱气的电解质溶液做了上述实验,发现替换前和替换后电容变化很小。由此证明了,醇水替换法也可以在玻碳电极表面产生纳米气泡。并且可以用电化学工作站测试出其对电极的影响的大小。
[Abstract]:In recent years, interface problems have become more and more difficult and hot. The existence of nano-bubbles at the solid-liquid interface originates from the study of the mechanism of surface hydrophobic long-range gravity. In the classical thermodynamic theory, nanometer bubbles in water at room temperature are considered to be unstable. In recent years, many phenomena on hydrophobic surfaces have shown that there are nano-bubbles at the solid-liquid interface. The existence of nano-bubbles has been confirmed by neutron diffraction technique and atomic force microscope (AFM). The most important thing is to make use of atomic force microscope (AFM) to study the imaging of nano bubbles, which proves the existence of nano bubbles. At present, atomic force microscope (AFM) (AFM). Is the most powerful method for direct detection of nanoscale bubbles at solid-liquid interface. When AFM is used to image the nanometer bubble, the substrate with flat surface is usually chosen. There are high-order pyrolytic graphite (HOPG), mica, gold, polystyrene film and so on. Up to now, the formation methods of nano-bubble have been widely studied, such as alcohol-water substitution, different solution substitution, direct drop addition, direct impregnation, rapid heating, electrochemical method and so on. Among them, the substitution method is one of the most studied methods in recent years. Alcohol-water substitution is a highly reproducible method which can generate a large number of nano-bubbles on different substrates. However, some organic substrates can not be used in organic solvents, and it is easy to introduce impurities due to the use of organic solvents. Therefore, in order to overcome these shortcomings, we need to find some new preparation methods of nano-bubble. Ultrasound gives us a new way of thinking. The cyclic voltammetry curves of the glassy carbon electrode were measured by the combination of nanometer bubbles produced by ultrasonic and electrochemical workstation. In this experiment, we used the degassed electrolyte solution and the undegassed electrolyte solution in the experiment, respectively. The formation of nanometer bubbles was obtained by comparing the two experimental results. We also studied the effect of ultrasonic time on the formation of nanometer bubbles. The longer the ultrasonic time, the more the capacitance of double layer decreased until the change was stable. According to the derivation, the nanometer bubble has larger and larger electrode coverage area with the increase of ultrasonic time. The influence of ultrasonic frequency, with the increase of ultrasonic frequency, the double-layer capacitance also decreases continuously until the change is stable. According to the theoretical derivation of double-layer capacitance and the experimental results, we get, With the increase of ultrasonic frequency, the relative dielectric constant is decreasing, so the nanometer bubble is continuously covering the electrode surface. With the increase of ultrasonic frequency, the capacitance is decreasing, the nanometer bubble is increasing and the click-area is increasing. In addition, we also use the traditional alcohol-water replacement method to produce nano-bubbles on the surface of glassy carbon electrode, and then use an electrochemical workstation to test the effect on the electrode. The capacitance before and after substitution was measured by the method of alcohol-water substitution, and it was found that the capacitance became smaller after substitution. According to the theoretical derivation and experimental results, nano-bubbles were produced on glassy carbon electrode after the substitution of alcohol and water. We have done the above experiments with degassed alcohols, degassed water and degassed electrolyte solutions. It is found that the capacitance changes are very small before and after replacement. It is proved that nano-bubbles can also be produced on the surface of glassy carbon electrode by water-alcohol replacement method. The influence of the electrode on the electrode can be measured by an electrochemical workstation.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O657.1;TB383.1

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