Abstract: By introducing Ni atoms, the out layer electrons of the Pd cluster become more easily to transit from the d sub-orbital of Pd to the p orbital of O2 and pass more charge to oxygen. The more charge the oxygen owns, the longer the bond length becomes, and more easily for the O–O bond to break up. Thus, oxygen reduction reaction activity is enhanced.

Key words: palladium, nickel, oxygen reduction reaction, fuel cell, cluster model, density functional theory