Surface-enhanced Raman scattering (SERS) integrates high levels of sensitivity and spectroscopic precision with tremendous potential for chemical and biomolecular sensing. On the other hand, metal nanoparticles have been employed in catalysis with great promise for future energy technologies. Interactions between oxygen and gold surfaces are of fundamental importance in catalysis and other multiple and diverse areas of science and technology. We propose to synergistically integrate the two aspects of metal nanoparticles in dual-functional Ag@Au core-shell nanostructures to take advantage of high SERS enhancement factor of Ag and unique catalytic property of Au. Pure Au nanoparticles with specific size are also prepared to be a comparison with Ag@Au core-shell structures in terms of SERS enhancement and catalytic properties by in situ Raman detection during the decomposition of hydrogen peroxide.
Current industrial technologies for selective oxidation of propene via a single-stage oxidation process in H2/O2 catalyzed by Au holds excellent prospect of green production of C3H6O. Fundamentals of the molecular mechanisms between catalytic Au and the oxidant remain unclear for decades, however, impeding the development of its rational design and implementation. We explore a multifunctional, highly organized nanoporous anodized aluminum oxide (AAO) substrate with immobilized Au nanoparticles (Au NPs) both as a catalytic reactor and an ultra-sensitive SERS probe to investigate the molecular level details during Au-catalyzed oxidation of propene in situ. Nanoporous AAO offers excellent thermal stability and enhanced particle coverage density for the immobilized Au NPs within to enable high temperature SERS interrogation, opening up new opportunities in the study of the catalytic reactions. Different size of Au NPs and pores of AAO are explored for improved SERS sensitivity and catalytic activity.