Lecture
WEB Real-time TEM investigation of the coarsening of nanoporous gold nanowires by in-situ annealing
Friday (25.09.2020) 13:20 - 13:35 C: Characterization 2 Part of:Nanoporous materials are promising candidates for the development of highly efficient energy storage devices allowed by their high specific surface area. Thus, the precise control of the pore and ligament size is a key parameter for the development of such devices. The most used technique to create a nanoporous structure is the dealloying process due to its accuracy and simplicity. It consists in removing the less noble metal from an alloy in order to create the nanoporous structure. This step is then followed by the diffusion of the most noble metal onto the surface and ultimately to the coarsening of the overall structure. The theoretical model underlying the porosity evolution during dealloying has been well established. However, a lack of experimental support is critical. Indeed, only a few in-situ experiments have been reported so far including X-ray diffraction (and scattering), optical analysis, and scanning tunneling microscopy. Only recently, in-situ TEM experiments have been carried out on nanoporous structure paving the way through the real-time observation and investigation of the process. This improvement is mainly allowed by the progress in new generations of sample holders. In this work, we report an in-situ TEM study of the coarsening of the nanoporous structure. In order to perform this analysis, nanoporous nanowires with different pore and ligament sizes were analyzed. It is well reported that the coarsening is observed either during dealloying than during annealing. Indeed, the evolution of the morphology during annealing was recorded by TEM. We highlight the two coarsening behavior reported in the literature for nanoporous samples depending on the pore and ligament size.
