In this study, a facile and nontoxic synthetic method of well-covered Cu-Ag core-shell nanoparticles (Cu@Ag NPs) was determined. Through chemical reduction reaction in a modified silver ammonia solution with gelatin additive, the as-synthesized Cu@Ag NPs showed attractive comprehensive characteristics, including small and narrow size distribution, low proportion of Ag, dense and uniform Ag shell, good dispersibility, good sphericity, and desirable oxidation resistance. Based on electrochemical analysis, a complexing model was proposed to explain the effects of gelatin on the deposition of Ag. It revealed that the gelatin acted as not only the steric hindrance but also the complexing agent and diffusivity modifier. The gelatin addition could increase the stability and decrease the decoupling rate of complexed Ag ions, thus leading to significant negative shift of the deposition potential and decrease of the deposition rate, promoting the formation of finer and thinner Ag shell. Our study proposes an applicable approach for the synthesis of Cu@Ag core-shell nanoparticles, and the complexing model can provide a theoretical tool to describe the effects of complexing agent on the synthesis of Cu@Ag and other bimetallic nanoparticles.

在这项研究中，确定了一种简便且无毒的合成方法，该方法可以很好地覆盖铜-银核壳纳米粒子（Cu @ Ag NPs）。通过在明胶添加剂的改性银氨溶液中进行化学还原反应，合成后的Cu @ Ag NPs具有吸引人的综合特性，包括小而窄的粒度分布，低的Ag比例，致密且均匀的Ag壳层，良好的分散性，良好的球形性，并具有理想的抗氧化性。基于电化学分析，提出了络合模型以解释明胶对银沉积的影响。结果表明，明胶不仅起位阻作用，而且还起络合剂和扩散性调节剂的作用。添加明胶可以增加复合Ag离子的稳定性并降低其去耦速率，因此导致沉积电位的显着负迁移并降低沉积速率，从而促进了形成更细，更薄的Ag壳层。我们的研究提出了一种适用于合成Cu @ Ag核壳纳米粒子的方法，并且该络合模型可以提供一个理论工具来描述络合剂对Cu @ Ag和其他双金属纳米粒子合成的影响。