Used in-situ EC-STM to study theabsorption structures and electrochemical polymerization mechanism of aniline on single crystal Au (111) face

• Main Authors: Shu-hua liu, 劉淑華
• Other Authors: Chun-Guey Wu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/74107714480327348422

碩士 === 國立中央大學 === 化學研究所 === 94 === The mechanism of electrochemical polymerization of conjugated polymers such as polyaniline has been well studied. Nevertheless, the proposed mechanisms were derived from the indirect evidences. As we known, so far no article has reported the polymerization mechanism derived directly from the observation of the reaction for aniline in molecular level. In this study we used in-situ EC-STM to study the absorption structures and electrochemical polymerization mechanism of aniline on single crystal Au (111) face. It was found that two absorption structures were found under different applied potentials: (√13 × √31) with θ (the surface coverage) of 0.20 was formed at the potential of 0.60V (vs RHE) and (√13 × 5) with θ of 0.25 was observed when the applied potential was raised to 0.65V (vs RHE). When the potential was raised to the polymerization potential (0.95V vs RHE) of aniline, the absorbed aniline molecules start to polymerize at the same time some Au nanoparticles which have a similar size and arranged regularly were formed. When the applied potential was raise to the polymerization potential (1.2 V vs RHE) of aniline abruptly, aniline was polymerized and absorbed on the surface of Au (111). The formed polyaniline chains contain straight and curved parts. The width of the polymer chains is about 0.7 nm and it is a monolayer coverage in the beginning but later on double-layer absorption was also observed. When the applied potential was decreased gradually, the second layer of polyaniline chains fell off but the first layer still absorbed tightly on the Au (111) electrode.