美国华盛顿大学Bo Zhang团队报道了单个银纳米粒子在聚硫修饰微电极上的碰撞、粘附和氧化。相关研究成果发表在2021年9月22日出版的《美国化学会杂志》。

研究人员报道了单个银纳米颗粒在多硫化物修饰金微电极上的碰撞、粘附和氧化行为。尽管NP碰撞电化学方法在较小Ag NPs的体积分析方面取得了显著成功，但由于无法控制碰撞行为和NP不完全氧化，该方法未能分析大于50 nm的颗粒。

该文中，研究人员描述了超薄多硫化物层通过显著提高银纳米颗粒在电极上的粘附概率来控制其碰撞行为的独特能力。超薄含硫层通过硫代硫酸钠电氧化在金上形成，既作为碰撞NPs的粘合界面，又作为化学氧化Ag形成Ag₂S的预浓缩反应介质。作为Lewis碱的本体硫代硫酸钠的存在进一步促进了颗粒的快速溶解，从而使生成的Ag₂S的溶解度显著提高了1013倍。多硫化物和硫代硫酸钠的联合使用使研究人员能够观察到NP检测频率增加25倍，峰值振幅增加3倍，并且对于较大的Ag NP更完全的氧化。通过认识到使用透射电子显微镜（TEM）进行体积分析可能会高估准球形NPs，研究人员相信可以对高达100 nm的颗粒进行完全NP氧化。

通过聚焦更有效的NP电极接触的电极/溶液界面，研究人员期望从该研究中获得的知识将极大地有助于未来的NP碰撞系统，用于单体电化学的机理研究以及超灵敏生化传感器的设计。

附：英文原文

Title: Collision, Adhesion, and Oxidation of Single Ag Nanoparticles on a Polysulfide-Modified Microelectrode

Author: Peter A. Defnet, Bo Zhang

Issue&Volume: September 22, 2021

Abstract: We report the collision, adhesion, and oxidation behavior of single silver nanoparticles (Ag NPs) on a polysulfide-modified gold microelectrode. Despite its remarkable success in volume analysis for smaller Ag NPs, the method of NP-collision electrochemistry has failed to analyze particles greater than 50 nm due to uncontrollable collision behavior and incomplete NP oxidation. Herein, we describe the unique capability of an ultrathin polysulfide layer in controlling the collision behavior of Ag NPs by drastically improving their sticking probability on the electrode. The ultrathin sulfurous layer is formed on gold by sodium thiosulfate electro-oxidation and serves both as an adhesive interface for colliding NPs and as a preconcentrated reactive medium to chemically oxidize Ag to form Ag2S. Rapid particle dissolution is further promoted by the presence of bulk sodium thiosulfate serving as a Lewis base, which drastically improves the solubility of generated Ag2S by a factor of 1013. The combined use of polysulfide and sodium thiosulfate allows us to observe a 25× increase in NP detection frequency, a 3× increase in peak amplitude, and more complete oxidation for larger Ag NPs. By recognizing how volumetric analysis using transmission electron microscopy (TEM) may overestimate quasi-spherical NPs, we believe we can have full NP oxidation for particles up to 100 nm. By focusing on the electrode/solution interface for more effective NP-electrode contact, we expect that the knowledge learned from this study will greatly benefit future NP collision systems for mechanistic studies in single-entity electrochemistry as well as designing ultrasensitive biochemical sensors.

DOI: 10.1021/jacs.1c07164

Source: https://pubs.acs.org/doi/10.1021/jacs.1c07164