Intartaglia Romuald, Rodio Marina, Abdellatif Mohamed, Prato Mirko, Salerno Marco
Nanophysics Department, Istituto Italiano di Tecnologia, Genoa I-16163, Italy.
Nanostructures Department, Istituto Italiano di Tecnologia, Genoa I-16163, Italy.
Materials (Basel). 2016 Sep 14;9(9):775. doi: 10.3390/ma9090775.
Colloidal gold nanoparticles are a widespread nanomaterial with many potential applications, but their aggregation in suspension is a critical issue which is usually prevented by organic surfactants. This solution has some drawbacks, such as material contamination and modifications of its functional properties. The gold nanoparticles presented in this work have been synthesized by ultra-fast laser ablation in liquid, which addresses the above issues by overcoating the metal nanoparticles with an oxide layer. The main focus of the work is in the characterization of the oxidized gold nanoparticles, which were made first in solution by means of dynamic light scattering and optical spectroscopy, and then in dried form by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and finally by surface potential measurements with atomic force microscopy. The light scattering assessed the nanoscale size of the formed particles and provided insight in their stability. The nanoparticles' size was confirmed by direct imaging in transmission electron microscopy, and their crystalline nature was disclosed by X-ray diffraction. The X-ray photoelectron spectroscopy showed measurements compatible with the presence of surface oxide, which was confirmed by the surface potential measurements, which are the novel point of the present work. In conclusion, the method of laser ablation in liquid for the synthesis of gold nanoparticles has been presented, and the advantage of this physical approach, consisting of coating the nanoparticles in situ with gold oxide which provides the required morphological and chemical stability without organic surfactants, has been confirmed by using scanning Kelvin probe microscopy for the first time.
胶体金纳米颗粒是一种广泛应用的纳米材料，具有许多潜在应用，但它们在悬浮液中的聚集是一个关键问题，通常需要有机表面活性剂来防止。这种解决方案存在一些缺点，例如材料污染及其功能特性的改变。本文介绍的金纳米颗粒是通过液体中的超快激光烧蚀合成的，该方法通过用氧化层包覆金属纳米颗粒来解决上述问题。这项工作的主要重点是对氧化金纳米颗粒进行表征，首先通过动态光散射和光谱学在溶液中进行表征，然后通过透射电子显微镜、X射线衍射、X射线光电子能谱对干燥形式的颗粒进行表征，最后通过原子力显微镜进行表面电位测量。光散射评估了所形成颗粒的纳米级尺寸，并提供了有关其稳定性的见解。通过透射电子显微镜中的直接成像确认了纳米颗粒的尺寸，并通过X射线衍射揭示了它们的晶体性质。X射线光电子能谱显示的测量结果与表面氧化物的存在相符，表面电位测量证实了这一点，这是本工作的新亮点。总之，本文介绍了用于合成金纳米颗粒的液体激光烧蚀方法，并且通过首次使用扫描开尔文探针显微镜证实了这种物理方法的优势，即原位用金氧化物包覆纳米颗粒，在不使用有机表面活性剂的情况下提供所需的形态和化学稳定性。
