Synergistic electrocatalytic effect of Pd and Rh nanoislands co-deposited on Au(poly) on HER in alkaline solution

Abstract

Hydrogen evolution reaction (HER) was explored on tri-metallic Rh@Pd/Au(poly) and bimetallic Pd/Au(poly) and Rh/Au(poly) electrodes in alkaline solution. Electrodes were prepared by the spontaneous deposition of either Pd or Rh and by co-deposition of both Rh and Pd on polycrystalline gold electrode. Characterization of modified electrodes was performed by cyclic voltammetry in alkaline solution, while additional information about phase analysis, chemical composition and surface morphology of tri-metallic Rh@Pd/Au(poly) electrode were acquired using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and atomic force microscopy. Investigations of HER catalysis have shown that the activity of tri-metallic Rh@Pd/Au(poly) electrode exceeds the activities of both Pd/Au(poly) and Rh/Au(poly) electrodes, meaning that the synergism between co-deposited Pd and Rh islands is achieved. Moreover, Rh@Pd/Au(poly) electrode showed significant approach to the activities of bulk Pd and Rh electrodes for HER, especially when taking into account low activity of bare Au substrate. Synergistic effect of co-deposited Pd and Rh islands is a consequence of the strong electronic interaction between three metals in a close contact, which promotes the activity for HER by lowering the adsorption energy of Hads intermediate.