Improved Stability of Octahedral PtCu by Rh Doping for the Oxygen Reduction Reaction

Abstract

AbstractOctahedral Pt−M nanocrystals are recognized to be ideal catalysts for the oxygen reduction reaction (ORR) because of their outstanding electrocatalytic activity. However, these high‐activity catalysts usually show shortage in the long‐term stability since the octahedral morphology is severely destroyed and transition metals are easily leached out during the electrochemical test. Herein, we prepared octahedral PtCu and PtCuRh0.05 nanocrystals with an edge length of about 15 nm. After being dispersed on carbon black, the octahedral PtCu/C catalyst exhibits a very high ORR activity with a specific activity and mass activity of 3.29 mA cm−2 and 1.12 A mgPt−1 at 0.90 V, making it among one of the most active PtCu catalyst for ORR ever reported. Although the incorporation of Rh slightly decreases the ORR activity, it can improve the stability, and the half‐wave potential is only shifted negatively by 1 mV after an accelerated durability test of 10,000 potential cycles for the PtCuRh0.05/C catalyst. The improved stability is attributed to the anchoring effect of the Rh atoms, which inhibits the leaching of Cu and helps to maintain the octahedral morphology during the ORR.