SERS and catalytically active Ag/Pd nanoparticles obtained by combining laser ablation and galvanic replacement

Bimetallic Ag/Pd nanoparticles were fabricated by laser ablation of a silver target in water and successive addition of palladium nitrate to promote a partial galvanic replacement of silver with palladium. The obtained nanoparticles, as shown by a microscopic investigation coupled with EDX and SAED analysis, exhibit a silver core, able to produce SERS enhancement, and a Pd cloudy shell at the surface that can interact with organic molecules in catalytic reactions. The test was carried out using as a molecular probe an aromatic nitroderivative, which, by adsorption on the metal substrate, undergoes an almost total reduction to azoderivate, as evidenced by the comparison between the SERS spectra recorded on pure Ag and Ag@Pd nanoparticles.