Revealing the Role of Interfacial Properties on Catalytic Behaviors by in Situ Surface-Enhanced Raman Spectroscopy

Insightful understanding of how interfacial structures and properties affect catalytic processes is one of the most challenging issues in heterogeneous catalysis. Here, the essential roles of Pt–Au and Pt−oxide−Au interfaces on the activation of H₂ and the hydrogenation of para-nitrothiophenol (pNTP) were studied at molecular level by in situ surface-enhanced Raman spectroscopy (SERS) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Pt–Au and Pt–oxide–Au interfaces were fabricated through the synthesis of Pt-on-Au and Pt-on-SHINs nanocomposites. Direct spectroscopic evidence demonstrates that the atomic hydrogen species generated on the Pt nanocatalysts can spill over from Pt to Au via the Pt–Au and Pt–TiO₂–Au interfaces, but would be blocked at the Pt–SiO₂–Au interfaces, leading to the different reaction pathways and product selectivity on Pt-on-Au and Pt-on-SHINs nanocomposites. Such findings have also been verified by the density functional theory calculation. In addition, it is found that nanocatalysts assembled on pinhole-free shell-isolated nanoparticles (Pt-on-pinhole-free-SHINs) can override the influence of the Au core on the reaction and can be applied as promising platforms for the in situ study of heterogeneous catalysis. This work offers a concrete example of how SERS/SHINERS elucidate details about in situ reaction and helps to dig out the fundamental role of interfaces in catalysis.