Artmann Evelyn, Schmider Tobias, Jacob Timo, Engstfeld Albert K
Institute of Electrochemistry, Ulm University, D-89081, Ulm, Germany.
Chemphyschem. 2023 Oct 4;24(19):e202300428. doi: 10.1002/cphc.202300428. Epub 2023 Aug 2.
Nanoporous Au (NPG) has different properties compared to bulk Au, making it an interesting material for numerous applications. To modify the structure of NPG films for specific applications, e. g., the porosity, thickness, and homogeneity of the films, a fundamental understanding of the structure formation is essential. Here, we focus on NPG prepared via electrochemical reduction from Au oxide formed during high voltage (HV) electrolysis on poly-oriented Au single crystal (Au POSC) electrodes. These POSCs consist of a metal bead, with faces with different crystallographic orientations and allow screening of the influence of crystallographic orientation on the structure formation for different facets in one experiment. The HV electrolysis is performed between 100 ms and 30 s at 300 V and 540 V. The amount of Au oxide formed is determined by electrochemical measurements and the structural properties are investigated by scanning electron and optical microscopy. We show that the formation of Au oxide is mostly independent of the crystallographic orientation, except for thick layers, while the macroscopic structure of the NPG films depends on experimental parameters such as the Au oxide precursor thickness and the crystallographic orientation of the substrate. Possible reasons for the frequently observed exfoliation of the NPG films are discussed.
与块状金相比，纳米多孔金（NPG）具有不同的性质，这使其成为众多应用中一种有趣的材料。为了针对特定应用修改NPG薄膜的结构，例如薄膜的孔隙率、厚度和均匀性，对结构形成的基本理解至关重要。在这里，我们关注通过在多晶取向的金单晶（Au POSC）电极上进行高压（HV）电解形成的金氧化物经电化学还原制备的NPG。这些POSC由一个金属珠组成，其表面具有不同的晶体学取向，并且在一个实验中可以筛选晶体学取向对不同晶面结构形成的影响。HV电解在300 V和540 V下于100 ms至30 s之间进行。通过电化学测量确定形成的金氧化物的量，并通过扫描电子显微镜和光学显微镜研究其结构性质。我们表明，除了厚层外，金氧化物的形成大多与晶体学取向无关，而NPG薄膜的宏观结构取决于诸如金氧化物前驱体厚度和基底的晶体学取向等实验参数。讨论了NPG薄膜经常观察到的剥落现象的可能原因。
