Imaging the Site-Specific Activity and Kinetics on a Single Nanomaterial by Microchamber Array

One-dimensional (1D) and two-dimensional (2D) nanomaterials usually show diverse catalytic activities at different locations. For a particular location, the local reaction activity could be too fast to be measured by super-resolution microscopy (SRM). To solve this problem, this research uses a large array of polydimethylsiloxane (PDMS) microchambers to resolve the site-specific activity on a single gold nanoplate with micrometer resolution, in situ and in real time. This research presents a general method to screen the catalytic activity distribution on single nanomaterials, even if the local activity is up to TOF = 5.9 x 10(5) s(-1), the adsorption time of the fluorescent molecule is short, and fluorescence quenching occurs on the nanomaterials. This research reveals that the site-specific activities of different regions on a single gold nanoplate follows the trend corner > edge > flat facet. This research also reveals that the site-specific activities of the flat facet and corner regions are not dependent on the size of the gold nanoplate, while the site-specific activity of the edge region is positively dependent on the size. The positive correlation is due to the increasing roughness of the edges with the size of the gold nanoplates. Larger roughness indicates more defects with higher reactivity. In addition, we found two kinds of catalytic kinetic pathways: i.e., the direct pathway and the indirect pathway. We further studied the effect of the size, region, and shape of the gold nanoplate on the direct pathway. Finally, the approach developed in this research exhibits many advantages, including high sensitivity, low reagent consumption, reusability, and recyclability, which make it generally applicable in many other types of reactions, including electrochemical and photochemical reactions.