Ultra-thin silver nanowires' synthesis in pore- confined space of mesoporous silica thin film

In the present work, we report a synthesis procedure for the preparation of vertically aligned mesoporous silica thin films containing long, nanometer-scale thin silver nano-wires inside pores. The inter-channel nanowires had a fine crystalline structure and a diameter of no more than 2 nm. Despite the diameter being the edge of the theoretical possibility of synthesis, the nanowires were stable enough to be observed by transmission electron microscope and could be clearly observed. For the synthesis, we applied the idea of silica nanoreactors, and the procedure consists of two steps: fabrication of an initial organically-functionalized silica thin film containing silver ions distributed regularly inside vertically aligned pores and following thermal decomposition resulting in the decompo-sition of the organic anchoring groups and the formation of metallic crystalline nanowires from released silver atoms. Both the final nanocomposite and the initial material were studied by means of transition electron microscopy and electrochemical techniques: linear scan and differential pulse anodic stripping voltammetry. The crystallinity of silver nanowires inside silica mesopores was proved by electron diffraction. The spatial confinement realized by silica nanochannels facilitated the stabilization of relatively small and ultra-thin nanowires and the formation of a hexagonal P63/mmc silver crystalline structure instead of the more common Fm3m cubic. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

This work presents a synthesis procedure for preparing vertically aligned mesoporous silica thin films with long nanometer-scale silver nanowires inside pores. The nanowires have a fine crystalline structure and a diameter of no more than 2 nm. The synthesis involves the use of silica nanoreactors and consists of two steps: fabricating an organically-functionalized silica thin film with regularly distributed silver ions inside vertically aligned pores, and thermally decomposing the film to form metallic crystalline nanowires. The resulting nanocomposite and initial material were characterized using electron microscopy and electrochemical techniques. The confinement provided by silica nanochannels enables the stabilization of small and ultra-thin nanowires and the formation of a hexagonal silver crystalline structure.