Core–shell-structured nanoporous PtCu with high Cu content and enhanced catalytic performance†
A core–shell-structured bimetallic nanoporous PtCu catalyst with a high non-noble metal content (Cu: ∼55 at%) and uniformly distributed ultrafine ligaments (∼3 nm) is fabricated by one-step dealloying a well-designed Pt4Cu21Mn75 single-phase ternary precursor in 1 M (NH4)2SO4 aqueous solution. The one-step dealloying involves a two-step corrosion process: one is fast dealloying the most active Mn from the ternary alloy to form nanoporous PtCu and the next step is a slow dealloying process which would slowly dissolve Cu from the PtCu alloy ligament surface forming a core–shell-structured nanoporous PtCu alloy with a Pt shell and a PtCu alloy core. Electrochemical measurements manifest that the core–shell-structured nanoporous PtCu exhibits greatly enhanced catalytic activity towards the electro-oxidation of methanol and formic acid compared with both nanoporous Pt and the state-of-the-art Pt/C catalyst. With evident advantages of facile preparation and enhanced catalytic performance, the nanoporous core–shell-structured PtCu catalyst is very promising as an anode catalyst in fuel cells. Moreover, this strategy (i.e., dealloying well-designed Mn-based ternary alloys) can also be used to fabricate other uniform nanoporous core–shell-structured alloys such as the nanoporous NiCu alloy.