Electrochemical synthesis of Rh-Pd bimetallic nanoparticles onto a glassy carbon surface

Rh-Pd bimetallic nanoparticles were prepared successfully by sequential electrodeposition on a glassy carbon (GC) substrate using single potentiostatic pulses. The generated particles were characterized by ex-situ atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Initially, AFM images evidenced hemispherical-shaped Pd crystals distributed preferably over the GC surface defects. Size diversity of the formed deposits indicates a progressive nucleation mechanism with a three-dimensional growth. Subsequent Rh deposition does not introduce significant morphological changes. Voltammetric results suggested that Rh is deposited over Pd nanocrystals forming a core-shell type structure. XPS analysis confirms that Pd and Rh are present on the surface, both as metal and as oxide compounds. The relative amount of Rh greater than that of Pd, corroborates that Rh atoms were preferentially at the surface of the bimetallic particles as a shell over the Pd core. The electrocatalytic effect of the Rh-Pd/CV modified electrode was evaluated qualitatively for the hydrogen evolution reaction.