Probing single‐atom catalysts and catalytic reaction processes by shell‐isolated nanoparticle‐enhanced Raman spectroscopy

Developing advanced characterization techniques for single-atom catalysts (SACs) is of great significance to identify their structural and catalytic properties. Raman spectroscopy can provide molecular structure information thus is a promising tool for catalysis, but its application in SACs remains a great challenge due to its low sensitivity. Herein, we develop a highly sensitive strategy that achieves the characterization of the structure of SACs and in situ monitoring of the catalytic reaction processes on them by shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) for the first time. Using such a strategy, Pd SACs on different supports are identified by Raman spectroscopy, and the nucleation process of Pd species from single atoms to nanoparticles has been revealed. Moreover, the catalytic reaction processes of the hydrogenation of nitrocompounds on Pd SACs are in situ monitored, and molecular insights are obtained to uncover the unique catalytic properties of SACs. This work provides a new spectroscopic tool for the in situ study of SACs, especially at solid-liquid interfaces.