In situ tracking of catalytic processes and capturing their active intermediates under working conditions by various spectroscopic techniques are of significant importance in heterogeneous catalysis. Our group devotes continuously to unveil the structure-activity relationship of nanocatalysts and other materials with well-defined structures in thermal/photo catalysis using in situ spectroscopic techniques, especially shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Using SHINERS, we have achieved the in situ monitoring of the reaction processes and obtained direct evidence for intermediates that can hardly be in situ detected by other techniques, such as oxygen species, surface hydroxyl group, surface oxide, etc. We also focus on the development of plasmon-enhanced photocatalysts by the design and fabrication of plasmonic nanocomposites and have developed various efficient plamson-enhanced photocatalysts towards the water splitting and other photocatalytic reactions. Such plasmonic nanocomposites have also been used for the in situ study of photocatalytic reactions by enhanced Raman spectroscopy, which greatly helps the understanding of the reaction mechanism and the design of better catalysts.