Evolution of nanoporous Pt-Fe alloy nanowires by dealloying and their catalytic property for oxygen reduction reaction

The short life and high cost of carbon-supported Pt nanoparticle catalysts (Pt/C) are two main problems with proton exchange membrane fuel cells. Porous Pt alloy nanowires have more durability and catalytic activity than Pt/C. Dealloying is a facile way to make nanoporous Pt. However, the process of porosity formation is difficult to control. In this paper, electrospinning and chemical dealloying techniques are used to make long, thin and yet nanoporous Pt-Fe alloy nanowires. The evolution of nanoporosity is observed and studied. It is found that non-uniform composition in the precursor PtFe₅ alloy nanowires helps the formation of nanoporous structure. The overall wire diameter is about 10-20 nm and the ligament diameter only 2-3 nm. These porous long nanowires interweave to form a self-supporting network with a high specific activity, 2.3 times that of conventional Pt/C catalysts, and also have better durability. Long PtFe₅ alloy nanowires are made by electrospinning. Non-uniform composition in the alloy nanowires helps the formation of a nanoporous structure via a chemical dealloying method. These nanoporous Pt-Fe alloy long nanowires interweave into a porous film, which presents elevated specific activity and durability compared to nanoparticle Pt/C catalysts.