Incorporating Ag into Pd/Ni foam via cascade galvanic replacement to promote the methanol electro-oxidation reaction

In this work we intercalated an Ag layer between Pd surface and Ni substrate to form PdAg/Ni ternary architectures to promote the sluggish methanol oxidation reaction (MOR). The PdAg/Ni foam structures were prepared within short time via a cascade galvanic replacement method, in which an Ag precursor partially replaced a commercial Ni foam support first, followed by a Pd precursor partially replacing the formed Ag layer. X-ray diffraction and X-ray photoelectron spectroscopy proofs suggested that a part of the formed Ag was alloyed with the active Pd loaded on the Ni foam surface. It was interestingly found that: 1) incorporation of Ag into Pd/Ni foam could provide significantly improved electrocatalytic activities for the MOR, which mainly originated from the synergistic effects between Pd and Ag in the formed PdAg alloy; 2) the electrocatalytic activity of PdAg/Ni foam was highly dependent on the atomic ratio of Pd to Ag, and among synthesized electrocatalysts the best Pd₅₅Ag₄₅/Ni foam offered a mass activity of 3.3 times of the Pd/Ni binary counterpart; 3) the proposed Pd₅₅Ag₄₅/Ni foam also exhibited excellent performance durability during frequent cyclic voltammetric and simulated startup-shutdown measurements.