Hydrogen Evolution Electrocatalysis on AgPd(111) Alloys

Recent studies on AuPd(111) alloy surfaces display unexpected hydrogen evolution reaction activities—a unique activity of AuPd alloys with surface fractions of ~20% Pd was found. We investigated if this phenomenon also occurs with AgPd alloys. We first deposited Pd on a Ru(0001) substrate. After annealing, cyclic voltammetry investigations showed the same characteristics as Pd(111) single crystals. During Ag deposition, cyclic voltammetry experiments disclose underpotential deposition of Ag on the Pd film just as on Pd(111). AgPd alloys were formed by further annealing, and strong enrichment of Ag at the surface is observed. Using this approach, we prepared various bulk compositions at a film thickness of ~20 monolayers. Most AgPd alloys show a higher electrocatalytic activity than Ag or Pd alone. The activity trends match those seen with AuPd alloys.