TY  - JOUR
AU  - Tu, Jianxin
AU  - Yu, Shuo
AU  - Hao, Kui
AU  - Sun, Le
AU  - Bai, Ruicheng
AU  - Zhang, Fangzhou
AU  - Li, Aijun
AU  - Liu, Hong
PY  - 2024
TI  - Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect
JO  - Nano Research
SN  - 1998-0124
SP  - 7814
EP  - 7823
VL  - 17
IS  - 9
AB  - In this study, we successfully synthesized silicon nanotubes (Si-NTs) and silicon nanowires (Si-NWs) in a controllable manner using a catalyst- and template-free method through the direct electrolysis of SiO2 in a molten CaCl2-CaO system, while also proposing a novel formation mechanism for Si-NTs. Si-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO2 decomposition voltage. By subsequently adjusting the voltage to a value between the decomposition potentials of CaCl2 and CaO, in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs, leading to the formation of a Ca layer. The formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs, as the outward diffusion rate of Si exceeds the inward diffusion rate of Ca. These differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall effect. These vacancies gradually accumulate and merge, forming large voids, which ultimately result in the formation of hollow SiCa-NTs. Through a subsequent dealloying process, the removal of the embedded calcium leads to the formation of Si-NTs. Following the application of a carbon coating, the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g−1 at 1.5 A·g−1 and exhibits exceptional long-term cycling stability, maintaining a capacity of 977 mAh·g−1 after 2000 cycles at 3.0 A·g−1.
UR  - https://doi.org/10.1007/s12274-024-6842-8
DO  - 10.1007/s12274-024-6842-8