PdCu bimetallic nanoparticles (NPs) having mixed disordered face-centered cubic (fcc) and ordered body-centered cubic (B2-type) phases enhance the kinetics of oxygen reduction/evolution reaction by significant reduction of overpotentials, which leads to the superb round-trip efficiency of ∼80%. In addition, the PdCu catalyst demonstrates a remarkable cyclic enhancement in stability and an outstanding rate capability even at a high current density of 5000 mA gcarbon−1. Our first-principles calculations demonstrate that the low overpotentials of the PdCu catalyst are strongly correlated with the weak LiO2 adsorption strength, caused by electron transfer from Cu to the top-layer Pd atoms on the surface.
