Free-Standing 3D Hierarchical Carbon Foam-Supported PtCo Nanowires with “Pt Skin” as Advanced Electrocatalysts

Abstract

A two-step method was used for fabricating PtCo alloy nanowires supported on free-standing carbon foam network (PtCo-NWs/CF). First, Co nanowires (Co-NWs) were successfully in situ formed on CF (Co-NWs/CF) through a hydrothermal procedure with a subsequent post annealing treatment. Second, PtCo-NWs/CF composite was prepared via the displacement reaction between PtCl42- and the as-synthesized Co-NWs in the presence of ascorbic acid. Moreover, by a simple electrochemical process, a “Pt-skin” can be formed on the PtCo nanowires. Due to the 3D hierarchical micron-grade porous carbon support and the PtCo alloy nanowires with a synergy effect between Pt and Co, the PtCo-NWs/CF shows excellent electrocatalytic activity toward ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR, undergoes a 4e− pathway). The prepared PtCo-NWs/CF displayed a more negative onset potential and higher current density for the ethanol oxidation compared to commercial Pt/C and the Pt/CF. For ORR, at −0.6V, the PtCo-NW/CF shows a mass activity of 2.03AmgPt−1, which is almost 6.34 and 3.44 times higher than those of the commercial Pt/C (0.32AmgPt−1) and Pt/CF (0.59AmgPt−1). Such high electrocatalytic performances of the PtCo-NWs/CF for both ethanol oxidation and oxygen reduction render it a promising catalyst for fuel cells.