Ira A. Fulton School of Engineering, Arizona State University, Tempe, Arizona 85281, USA.
Nat Mater. 2013 Dec;12(12):1102-6. doi: 10.1038/nmat3741. Epub 2013 Aug 25.
Dealloying, the selective dissolution of one or more of the elemental components of an alloy, is an important corrosion mechanism and a technologically relevant process used to fabricate nanoporous metals for a variety of applications including catalysis, sensing, actuation, supercapacitors and radiation-damage-resistant materials. In noble-metal alloy systems for which the ambient-temperature solid-state diffusivity is minuscule, dealloying occurs at a composition-dependent critical potential above which bicontinuous nanoporous structures evolve and below which a full-coverage layer of the more-noble component forms causing the alloy surface to become passive. In contrast, for alloy systems exhibiting significant solid-state diffusive transport, our understanding of dealloying-induced morphologies and the electrochemical parameters controlling this are largely unexplored. Here, we examine dealloying of Li from Li-Sn alloys and show that depending on alloy composition, particle size and dealloying rate, all known dealloyed morphologies evolve including bicontinuous nanoporous structures and hollow core-shell particles. Furthermore, we elucidate the role of bulk diffusion in morphology evolution using chronopotentiometry and linear sweep voltammetry. Our results may have implications for lithium-ion battery development while significantly broadening the spectrum of strategies for obtaining new nanoporous materials through dealloying.
脱合金，即合金中一种或多种元素组分的选择性溶解，是一种重要的腐蚀机制，也是一种具有技术相关性的过程，用于制造用于各种应用的纳米多孔金属，包括催化、传感、致动、超级电容器和抗辐射损伤材料。在环境温度下固态扩散率极小的贵金属合金体系中，脱合金发生在依赖于组成的临界电位之上，在该电位之上形成双连续纳米多孔结构，而在该电位之下形成更贵金属组分的全覆盖层，导致合金表面钝化。相比之下，对于表现出显著固态扩散输运的合金体系，我们对脱合金诱导的形态以及控制这种形态的电化学参数的理解在很大程度上尚未得到探索。在这里，我们研究了 Li 从 Li-Sn 合金中的脱合金作用，并表明，根据合金组成、颗粒尺寸和脱合金速率，所有已知的脱合金形态都在演变，包括双连续纳米多孔结构和空心核壳颗粒。此外，我们使用恒电流电位法和线性扫描伏安法阐明了体扩散在形态演化中的作用。我们的结果可能对锂离子电池的发展有影响，同时通过脱合金显著拓宽了获得新型纳米多孔材料的策略范围。
