Trimetallic Nanotubes: A Bifunctional Substrate for the Catalytic and Spectroscopic Study Using Surface-enhanced Raman Spectroscopy

Surface-enhanced Raman scattering (SERS) has been used in various research fields because of high sensitivity and rapid data acquisition. When combined with catalysis in a bifunctional nanostructure, it is possible to monitor molecular transformations by providing information allowing a view of the reaction mechanism and kinetics. However, it is quite challenging to combine catalytic and SERS activities on the same material. This work aimed to produce bifunctional trimetallic nanotubes with catalytic and spectroscopic properties for catalysis and SERS monitoring of the cinnamyl alcohol oxidation reaction. The nanotubes synthesized were characterized by UV–vis, SEM, TEM, XPS, and ICP-OES. The XPS spectral analysis showed the formation of metal alloys containing Ag, Au, and Pd on the nanotubes' surface. The catalytic and spectroscopic results suggest a strong dependence on the ratio between the metals used in the nanocatalyst production for better catalytic performance and greater intensification of the Raman signal. With the SERS spectra and the results obtained by Gas chromatography, it was possible to suggest the reaction mechanism. Moreover, the stability of the catalyst was satisfactory, with 3 runs without loss of activity.