中文摘要：

用没食子酸一步液相还原制备粒度均匀和性质稳定的Au-Ag合金纳米粒子,研究在不同反应温度和Au/Ag摩尔比下Au-Ag合金纳米粒子的吸收光谱特性。实验结果表明Au-Ag合金纳米粒子仅有1个吸收峰,介于纯Ag和纯Au纳米粒子的吸收峰之间,且随着反应温度的提高,合金纳米粒子的最大吸收峰位逐渐蓝移,吸光度增加,半峰宽变窄。随着Au/Ag摩尔比的增加,合金纳米粒子的最大吸收峰位红移,且与其所含Au摩尔百分数呈线性关系。HRTEM表征结果说明制备的Au/Ag合金纳米粒子近球形、粒度均匀、无包覆现象。EDX分析结果证实单个纳米粒子由Au和Ag组成,其元素组成比与参加反应的Au/Ag摩尔比接近。

英文摘要：

Gold-silver alloy nanoparticles with a homogeneous size distribution and good stability were synthesized in aqueous solution by one-step reduction with gallic acid as reductant in the absence of other stabilizers for the first time. The absorption spectra of as prepared gold-silver alloy nanoparticles under different reaction temperatures and with various gold-silver mole ratios were studied. The absorption spectra exhibit only one single peak with the maximum wavelength located between the absorption peaks of Au nanoparticles and Ag nanoparticles, however, the absorption spectrum of the physical mixtures of Au nanoparticles and Ag nanoparticles exhibits two absorption peaks coming from their corresponding monometallic metal nanoparticles, suggesting primarily the formation of the alloy nanoparticles. The maximal absorption peaks of alloy nanoparticles showed gradually a blue-shift with the rising of reaction temperature eompanying with the increase in absorbance and the narrowing of peak shape. The maximum absorption wavelengths of alloy nanoparticles showed a red-shift with increasing Au/Ag molar ratio in a linear fashion, further indicating the formation of alloy nanoparticles. HRTEM images showed that the as-prepared alloy nanoparticles with Ag/Au molar ratio of 1 ： 1 are close to sphere in shape, homogeneous in size distribution and without capping phenomenon. EDX analysis suggested the present of Au and Ag in individual nanoparticles, and the Au/Ag mole ratio value of a sample with a nominal element composition was found to be close to the nominal value.