Synthesis and formation mechanism of Ag-Ni alloy nanoparticles at room temperature
Synthesis and formation mechanism of Ag-Ni alloy nanoparticles at room temperature
复制标题
室温Ag-Ni合金纳米粒子的合成及形成机制
DOI：
10.1016/j.jpcs.2016.06.013
复制
发表时间：
2016
影响因子：
4
通讯作者：
Wu Zhonghua
中科院分区：
文献类型：
--
作者：
Yan Shi;Sun Dongbai;Tan Yuanyuan;Xing Xueqing;Yu Hongying;Wu Zhonghua
以聚乙烯吡咯烷酮（PVP）为稳定剂，采用化学还原法制备了银镍纳米粒子。在Ag-Ni纳米粒子的合成过程中，使用硝酸银作为Ag+源，而六水合硫酸镍作为Ni 2+源。以Ag+源和Ni 2+源的混合溶液为前驱体，硼氢化钠为还原剂，制备了纳米银/镍复合氧化物。在相应的前驱体中制备了五种Ag+/Ni 2+（9：1、3：1、1：1、1：3和1：9）的悬浮液。采用该方法在室温下制备了Ag-Ni合金纳米颗粒。采用扫描电子显微镜（SEM）、能谱仪（EDS）、高分辨透射电子显微镜（HRTEM）对纳米粒子的形貌、组成和晶体结构进行了表征。用X射线衍射（XRD）分析了其晶体结构。在所有五种Ag/Ni比下，均观察到两种颗粒结构，分别为单晶结构和五重孪晶结构。计算了不同Ag/Ni比下不同晶体结构纳米颗粒的自由能。计算结果表明，在相同体积下，单晶颗粒的自由能低于多孪晶颗粒，且随着颗粒尺寸的增大，这种差异逐渐减小; Ni含量的增加会导致两种结构的自由能增加。不同晶体结构的形成取决于还原过程早期原始晶核的结构。
Ag–Ni nanoparticles were prepared with a chemical reduction method in the presence of polyvinylpyrrolidone (PVP) used as a stabilizing agent. During the synthesis of Ag–Ni nanoparticles, silver nitrate was used as the Ag+source while nickel sulfate hexahydrate was used as Ni2+source. Mixed solutions of Ag+source and Ni2+source were used as the precursors and sodium borohydride was used as the reducing agent. Five ratios of Ag+/Ni2+(9:1, 3:1, 1:1, 1:3, and 1:9) suspensions were prepared in the corresponding precursors. Ag–Ni alloy nanoparticles were obtained with this method at room temperature. Scanning electronic microscope (SEM), energy dispersive spectrum (EDS), high resolution transmission electron microscope (HRTEM) were used to characterize the morphology, composition and crystal structure of the nanoparticles. The crystal structure was also investigated with X-ray diffraction (XRD). In all five Ag/Ni ratios, two kinds of particle structures were observed that are single crystal structure and five-fold twinned structure respectively. Free energy of nanoparticles with different crystal structures were calculated at each Ag/Ni ratio. Calculated results revealed that, with identical volume, free energy of single crystal particle is lower than multi-twinned particle and the difference becomes smaller with the increase of particle size; increase of Ni content will lead the increase of free energy for both structures. Formation of different crystal structures are decided by the structure of the original nuclei at the very early stage of the reduction process.