CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy.
J Phys Condens Matter. 2011 May 4;23(17):175003. doi: 10.1088/0953-8984/23/17/175003. Epub 2011 Apr 14.
The results of a combined x-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) study of Ni nanoparticles (NP), before and after oxidation, are presented. An experimental set-up was realized for the preparation and study of pre-formed NP films, concentrating the attention on Ni NP in the diameter range between 4 and 8 nm. The XPS data were taken in situ from NPs after different stages of oxidation, including controlled dosing of O(2) gas in the experimental system and exposure to the atmosphere. The Ni 2p structure is a combination of spectra from metallic Ni in the NP core and from the oxide shell. The signal from the NP core was observed even for samples after exposure to air. From the comparison of HR-TEM experimental images with theoretical simulations, it was found that the Ni NP core has a regular multitwinned icosahedral structure, composed of single-crystal tetrahedra with (111) faces. The NiO phase is clearly observed forming islands on the NP surface.
本文介绍了对氧化前后的镍纳米颗粒（NP）进行结合 X 射线光电子能谱（XPS）和高分辨率透射电子显微镜（HR-TEM）研究的结果。实验中实现了用于制备和研究预形成 NP 薄膜的实验装置，重点关注直径在 4 至 8nm 之间的 Ni NP。XPS 数据是从 NP 在不同氧化阶段后原位采集的，包括在实验系统中受控剂量的 O(2)气体和暴露于大气中。Ni 2p 结构是 NP 核中金属 Ni 的光谱与氧化物壳的光谱的组合。即使在暴露于空气中的样品中也观察到了 NP 核的信号。通过将 HR-TEM 实验图像与理论模拟进行比较，发现 Ni NP 核具有由具有（111）面的单晶四面体组成的规则多孪晶二十面体结构。在 NP 表面上可以清楚地观察到形成岛的 NiO 相。
