Zhu Qi, Pan Zhiliang, Zhao Zhiyu, Cao Guang, Luo Langli, Ni Chaolun, Wei Hua, Zhang Ze, Sansoz Frederic, Wang Jiangwei
Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, 541004, China.
Nat Commun. 2021 Jan 25;12(1):558. doi: 10.1038/s41467-020-20876-9.
Nanoscale materials modified by crystal defects exhibit significantly different behaviours upon chemical reactions such as oxidation, catalysis, lithiation and epitaxial growth. However, unveiling the exact defect-controlled reaction dynamics (e.g. oxidation) at atomic scale remains a challenge for applications. Here, using in situ high-resolution transmission electron microscopy and first-principles calculations, we reveal the dynamics of a general site-selective oxidation behaviour in nanotwinned silver and palladium driven by individual stacking-faults and twin boundaries. The coherent planar defects crossing the surface exhibit the highest oxygen binding energies, leading to preferential nucleation of oxides at these intersections. Planar-fault mediated diffusion of oxygen atoms is shown to catalyse subsequent layer-by-layer inward oxide growth via atomic steps migrating on the oxide-metal interface. These findings provide an atomistic visualization of the complex reaction dynamics controlled by planar defects in metallic nanostructures, which could enable the modification of physiochemical performances in nanomaterials through defect engineering.
由晶体缺陷修饰的纳米级材料在诸如氧化、催化、锂化和外延生长等化学反应中表现出显著不同的行为。然而，在原子尺度上揭示精确的缺陷控制反应动力学（如氧化）对于实际应用仍然是一项挑战。在这里，我们使用原位高分辨率透射电子显微镜和第一性原理计算，揭示了由单个堆垛层错和孪晶界驱动的纳米孪晶银和钯中一般的位点选择性氧化行为的动力学。穿过表面的相干平面缺陷表现出最高的氧结合能，导致氧化物在这些交叉点优先成核。平面缺陷介导的氧原子扩散被证明通过在氧化物 - 金属界面上迁移的原子台阶催化随后的逐层向内氧化物生长。这些发现提供了由金属纳米结构中的平面缺陷控制的复杂反应动力学的原子尺度可视化，这可以通过缺陷工程实现纳米材料物理化学性能的改性。
