Ministry of Education Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350116, China.
College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, China.
Anal Chem. 2020 Jul 7;92(13):9016-9023. doi: 10.1021/acs.analchem.0c01129. Epub 2020 Jun 19.
Visualizing a chemical reaction process is critical for understanding the mechanism of the reaction. For example, information on chemical reactions involving single nanocatalysts has significant implications for mechanism research and is vital for guiding the selection of the most active nanocatalysts. In this work, dark field microscopy (DFM) is utilized to observe the electrocatalytic reaction process of Au-Pt core-shell nanoparticles (AuNPs@Pt) as an example. Hydrogen ions were reduced to hydrogen (H) on the surface of AuNPs@Pt under a certain potential, forming H nanobubbles covering the surface of AuNPs@Pt. As a result, the scattering intensity of the nanomaterial was observed to significantly increase under DFM. Therefore, the electrocatalytic reaction process could be monitored in real time by simply observing the scattering intensity change via DFM. Our investigation reveals a different nanobubble evolution process with an average nucleation time and lifetime of 0.69 and 32.34 s, respectively. Moreover, the catalytic activity between different nanomaterials was studied. The relationship between the Pt shell thickness and the average scattering intensity change reveals that the electrocatalytic activity is closely related to the Pt content. Finally, from the brightness of the scattering spot observed by DFM, the temporal and spatial distribution information on the catalytic activity could also be obtained, which is more abundant than the information obtained using the traditional electrochemical method.
可视化化学反应过程对于理解反应机制至关重要。例如，涉及单纳米催化剂的化学反应信息对于机制研究具有重要意义，对于指导选择最活跃的纳米催化剂也至关重要。在这项工作中，我们使用暗场显微镜（DFM）观察 Au-Pt 核壳纳米粒子（AuNPs@Pt）的电催化反应过程为例。在一定的电势下，氢离子在 AuNPs@Pt 表面还原为氢（H），形成覆盖 AuNPs@Pt 表面的 H 纳米气泡。结果，纳米材料的散射强度明显增加。因此，通过 DFM 简单观察散射强度的变化，就可以实时监测电催化反应过程。我们的研究揭示了一种不同的纳米气泡演化过程，其平均成核时间和寿命分别为 0.69 和 32.34 秒。此外，我们还研究了不同纳米材料之间的催化活性。Pt 壳层厚度与平均散射强度变化之间的关系表明，电催化活性与 Pt 含量密切相关。最后，从 DFM 观察到的散射点的亮度，还可以获得关于催化活性的时间和空间分布信息，这比使用传统电化学方法获得的信息更加丰富。
