Preparation Of Silver Nanowires Electrode And Its Electrocatalytic Properties

With the development of the industry, human being consume more and more fossil energy, meanwhile, CO2 in atmosphere is increased year by year. As is known to all, CO2 is the primary component of greenhouse gases, which causes greenhouse effect. The direct impact of CO2 content increase is the earth warming and consequential terrible calamity. Nowadays more and more attention has been paid for the fixation of CO2. Electrocarboxylation is an important method.Among all kinds of electrocarboxylation reactions, the electrocarboxylation of organic halides is a very important one. For the negative potential of halides reduction, the direct electrocarboxylation is difficult, with low yield, so electrocatalysis is often used. According to the difference of catalyst, the electrocatalytic carboxylation of organic haloids could be divided into two categories, homogeneous and heterogeneous. For homogeneous catalysis, organic metal complexes are commonly used as the catalyst. As it is dissolved in the reaction system, it is very difficult to separate. Thus, heterogeneous catalysis process has been paid more attention. Among the materials used in the heterogeneous electrocatalytic carboxylation of organic halides, silver is recognized to be the best one.Considering the advantageous of nano materials, silver nanowires electrode was proposed to be applied in the electrocatalysis to improve the catalytic ability of silver and to promote the fixation and application of CO2. In order to fabricate silver nanowires, well ordered anodic aluminum oxide template needs to be prepared. While for the corresponding application, electrocarboxylation process needs to be konwn. Thus, this thesis is mainly composed of three parts:the electrocarboxylation of 1-chloromethyl-4-vinyl-benzene, the preparation of anodic aluminum oxide temple, the preparation and electrocatalytic properties of silver nonowires.The first part is electrocarboxylation of 1-chloromethyl-4-vinyl-benzene. The electrolysis was investigated at atmospheric pressure in an undivided cell. The influences of solvent, supporting electrolytes, working electrodes, current densities and the charge supplied to the electrode were investigated to optimize the electrolytic conditions.The second part is preparation of anodic aluminum oxide temple Anodic aluminum oxide temples were successfully prepared in oxalic acid, phosphoric acid and sulfuric acid respectively by two-step anodization process. SEM was used to characterize the morphology of AAO prepared. The effect of annealing treatment and oxidation times on anodic aluminum oxide temples preparation were studied. The Influence of temperature on anodic aluminum oxide temples preparation was also studied, which turned out that temperature have nothing to do with aperture and pitch of holes but greatly increases the growth rate of anodic aluminum oxide temples. The influence of oxidation voltage on the aperture and pitch of holes was also investigated, which shows that aperture and pitch of holes were increased with the increasing of oxidation voltage. We combined voltage reduction sequence and chemical erosion together to find a universal way to remove barrier layer.The third part is about the preparation of nano-silver electrode and its electrocatalytic properties. Firstly, silver nano wire electrode was prepared with the assistance of anodic aluminum oxide temple by electrodeposition. Then, the nanoelectrode was applied to the electrocarboxylation of benzyl bromide and 1-chloromethyl-4-vinyl-benzene. The yield on nano silver electrode is higher than that on plain silver electrode, which indicates that the electrocatalytic property of nano silver electrode is better than that of plain silver electrode. The effects of AAO template type and silver amount were investigated to optimize the reaction yield.