In addition to the importance of the bulk crystal structure of the Pt-alloy NPs, de-alloying (activation) step of the electrocatalyst also holds a crucial importance . Relatively recently, transition metal cation (e.g. Ni, Co, Cu, Fe, …) contamination in the PEMFC has been recognised as another probable major contributor towards poor HCD performance when using Pt-alloys . On the other hand, certain transition metal cations were shown to diffuse into the membrane, causing formation of hydrogen peroxide radicals (due to the Fenton reaction ) that attack the membrane leading to failure of the PEMFC. Pt-Cu alloys have in the past shown severe durability issues due to proton starvation of the cathode as a result of Cu plating on to the anode Pt/C electrocatalyst and thus blocking the hydrogen oxidation reaction (HOR) .