Remarkable durability of Pt–Ir alloy catalysts supported on graphitic carbon nanocages

Abstract

Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology. To improve the electrochemical activity and durability of conventional Pt catalyst used in PEMFCs, we prepare Pt–Ir alloy catalysts supported on homemade graphitic carbon nanocages (CNCs). Results from cyclic voltammetry (CV) and linear sweep voltammetry (LSV) show that the alloy catalyst with an atomic Pt/Ir ratio of 1:1 supported on CNCs with a high degree of graphitization exhibits an excellent electrocatalytic activity. Furthermore, this alloy catalyst shows a drastic improvement in durability and stability over the unalloyed Pt catalyst supported on the same CNCs and the catalyst from a commercial source (Johnson Matthey Co.). It is found that the concurrent uses of well-graphitized CNCs as the support material and Ir as the alloying element are critical for the observed improvement. Such a Pt–Ir alloy catalyst provides a new replacement for the conventional Pt catalyst with not only a drastic improvement in durability but also a reduction in Pt usage by 50% as well.