RETRACTED: Nanoporous PtFe surface alloy architecture for enhanced methanol electro-oxidation (Retracted article. See vol. 22, pg. 25504, 2012)

By selectively dealloying PtFeAl ternary alloy in 0.5 M NaOH solution, a novel nanoporous PtFe (np-PtFe) alloy with nanorod-like morphology and inherent three-dimensional bicontinuous ligament-pore structure was successfully fabricated. X-Ray diffraction and electron microscope characterization demonstrated the crystal nature of the alloy ligament with ligament size down to similar to 3 nm. NaOH concentration plays a key role in the formation of a uniform PtFe alloy structure. Dealloying solution with a low NaOH concentration (0.5 M) is suitable for the formation of a pure PtFe alloy structure, while Fe3O4/np-PtFe nanocomposite is obtained when using a high NaOH concentration (>= 2 M). The np-PtFe alloy can be facilely converted into a nanoporous near-surface alloy structure with a Pt-rich surface and PtFe alloy core by a second dealloying process in dilute HNO3 solution. Electrochemical measurements show that the nanoporous near-surface alloy has greatly enhanced catalytic activity and durability towards methanol electro-oxidation compared with the state-of-the-art Pt/C catalyst. The peak current density of methanol electro-oxidation on the nanoporous surface alloy is about five times that on Pt/C. More importantly, continuous potential cycling from 0.6 to 0.9 V (vs. RHE) in 0.5 M H2SO4 aqueous solution demonstrates that the np-PtFe surface alloy has a better structural stability than commercial Pt/C. With evident advantages of facile preparation and enhanced electrocatalytic activity and durability, the np-PtFe surface alloy holds great potential as an anode catalyst in direct methanol fuel cells.