Catalytic activity of Ag/Pd bimetallic nanoparticles immobilized on quartz surfaces

New surface enhanced Raman scattering (SERS) substrates, composed of silver colloidal nanoparticles doped with palladium, immobilized on quartz surfaces, were prepared. The Pd clusters deposited on the Ag core acted as catalyst, while Ag ensured the SERS enhancement. These novel substrates were stable and maintained a satisfactory SERS efficiency even after a long time from the preparation. The catalytic activity of these bimetallic substrates was tested for 4-nitrobenzonitrile (NBN) and 4-nitro-3-pyrazole carboxylic acid (NPC), by means of SERS, scanning electron microscopy and surface plasmon resonance measurements. The SERS spectra showed that the nitrogroup was reduced to azogroup and aminogroup for NBN and NPC, respectively.