Hierarchical nanoporous PtFe alloy with multimodal size distributions and its catalytic performance toward methanol electrooxidation.

The hierarchical nanoporous (NP) PtFe alloy with multimodal size distributions is straightforwardly fabricated by means of mild de-alloying of the PtFeAl source alloy. This interesting NP structure consists of interconnected larger ligaments around hundreds of nanometers, in which these ligaments are also composed of the three-dimensional network structure with the typical size at 3 nm. In comparison to NP-Pt and Pt/C catalysts, the as-made alloy nanostructure exhibits superior electrocatalytic activity for the methanol oxidation reaction (MOR) with higher catalytic durability and CO tolerance besides the enhanced specific and mass activity. NP-PtFe also shows improved structure stability with the less loss of the electrochemical surface area of Pt upon long-term potential scan in acidic solution. X-ray photoelectron spectroscopy and density functional theory calculations demonstrate that the incorporation of Fe appropriately modified the electron structure of Pt with the downshift of the Pt d-band center, leading to a decreased CO poisoning and an improved MOR activity.