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. (C) 2014 Elsevier B.V. All rights reserved.