SERS, XPS and DFT investigation on palladium surfaces coated with 2,2′-bipyridine monolayers

Palladium surfaces, pretreated with a solution of 2,2′-bipyridine (bpy) as ligand molecule, were SERS-activated by means of laser-ablated Ag colloidal nanoparticles. XPS and Raman measurements, along with DFT simulations, evidenced the species formed on the metal surface as bpy-Pd(OH) 2 , which appears quite similar, from both structural and spectroscopic points of view, to the bpy-PdCl 2 coordination compound, whose catalytic activity is well known. Based on these observations, the use of Pd substrates coated with bpy is proposed for reactions of heterogeneous catalysis, instead of using bpy-PdCl 2 as homogeneous catalyst. Moreover, palladium nanoparticles could be prepared by laser ablation in aqueous solution of bpy, exhibiting both colloidal stability and catalytic activity.