电场辅助溶解法实现玻璃表面金纳米粒子的形貌控制
Morphology control of gold nanoparticles on glass surface realized by electric field assisted dissolution method
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摘要: 贵金属纳米粒子由于其非常独特的光学特性和表面活性,在光子学、催化和生物标识等方面都有非常重要的应用.采用离子溅射和后续热处理相结合的方法在玻璃表面形成了尺寸大约为60-80nm的单分散的球形金纳米粒子.在适当的温度条件下,采用步进式增加的强直流电场,实现了金纳米粒子的电场辅助溶解过程.在玻璃表面的不同颜色区域,初始球形的金纳米粒子溶解成月蚀状形貌.结合不同颜色区域内金纳米粒子的表面等离子体共振吸收性质和扫描电镜照片,研究了实验条件对金纳米粒子性质的影响.结合电场辅助溶解实验过程中的电流.电压特性,分析了金纳米粒子在强直流电场辅助下溶解的物理过程:金粒子中动出的电子向阳极的隧穿过程作为开始,随后是金阳离子向玻璃基体中的传输过程和阴极提供的电子与带有正电荷的金粒子相结合的过程.详细讨论了电场辅助溶解法实现金纳米粒子形貌控制的物理机制.Abstract: Noble metal nanoparticles have potential applications in photonics, catalysis, and bio-labeling, owing to their much unique optical properties and surface activities. Monodisperse spherical Au nanoparticles with sizes in a range of about 60-80 nm are formed on the glass surfaces via ion sputtering and follow-up heat treatment. At an appropriate temperature, the electric field assisted dissolution process of Au nanoparticles is realized by the strong direct current electric field in step-like feature. In the different color areas of glass surface, it can be found that the original spherical Au nanoparticles are dissolved into the particles with the shape of a lunar eclipse. From surface plasmon resonance absorption properties and scattering electron microscopy images of Au nanoparticles in the different color areas, the influence of experimental condition on property of gold nanoparticle is demonstrated. From the current- voltage characteristics in electric field assisted dissolution experimental process, the physical process of Au nanoparticle dissolution under strong direct current electric field is analysed: the tunneling process of ejected electrons from Au particles to the anode starts, then followed by transfer process of Au cations to the glass matrix and the combination process of electrons from cathode with a positive charge Au particles. The physical mechanism of morphology control of Au nanoparticles realized by electric field assisted dissolution method is discussed in detail.
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