Activity Trends of Binary Silver Alloy Nanocatalysts for Oxygen Reduction Reaction in Alkaline Media

The electrocatalytic activity of Pt‐based alloys exhibits a strong dependence on their electronic structures, but a relationship between electronic structure and oxygen reduction reaction (ORR) activity in Ag‐based alloys is still not clear. Here, a vapor deposition based approach is reported for the preparation of Ag 75 M 25 (M = Cu, Co, Fe, and In) and Ag x Cu 100− x ( x = 0, 25, 45, 50, 55, 75, 90, and 100) nanocatalysts and their electronic structures are determined by valence band spectra. The relationship of the d‐band center and ORR activity exhibits volcano‐shape behaviors, where the maximum catalytic activity is obtained for Ag 75 Cu 25 alloys. The ORR enhancement of Ag 75 Cu 25 alloys originates from the 0.12 eV upshift in d‐band center relative to pure Ag, which is different from the downshift in the d‐band center in Pt‐based alloys. The activity trend for these Ag 75 M 25 alloys is in the order of Ag 75 Cu 25 > Ag 75 Fe 25 > Ag 75 Co 25 . These results provide an insight to understand the activity and stability enhancement of Ag 75 Cu 25 and Ag 50 Cu 50 catalysts by alloying.