Surface Evolution of PtCu Alloy Shell over Pd Nanocrystals Leads to Superior Hydrogen Evolution and Oxygen Reduction Reactions

Pt-based electrocatalysts are by far the most effective for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), but they still suffer from high cost and insufficient overall performance. Improving Pt utilization via alloying or by forming corepshell structures is important for enhancing Pt activity and overall electrocatalytic performance. Herein, we report a simple seed-mediated method for synthesizing a dodecahedral PtCu alloy atomic shell on Pd nanocrystals. Significantly, such a Pd@PtCu nanocomposite with unique core@alloy-shell structure achieves a 25-fold and 6-fold enhancement of mass activity for HER and ORR, respectively, compared with the commercial Pt/C catalyst in acid media. Moreover, the unique Pd@PtCu catalyst shows only 1.0 mV increase in overpotential at 10 mA cm(-2) after 10 000 cycles for HER and almost no activity decay after 5 000 cycles for ORR, indicating the high endurance of Pd@PtCu in the electrochemical environment.