Strain engineering for Janus palladium-gold bimetallic nanoparticles: Enhanced electrocatalytic performance for oxygen reduction reaction and zinc-air battery

Strain existed in the bimetallic electrocatalysts may modulate the performance of oxygen reduction reaction (ORR). The density function theory calculation here indicates that the tensile strain originated from the mismatch of lattice spacing between Au and Pd is beneficial to decrease the reaction energy barrier for ORR. Pd-Au nanoparticles were uniformly loaded on graphene oxide (Pd-Au/GO) through the reduction of the Si-H bond. The epitaxial growth of Pd on Au leads to Janus nanostructure. X-ray powder diffraction patterns reveal that Pd is under an average tensile strain of + 0.32%, while high resolution transmission electron microscopy image demonstrates Pd near the Pd-Au interface under + 4% tensile strain. Better ORR performance of Pd-Au/GO is obtained than the commercial Pt/C in the alkaline medium. The tensile strain enables Pd-Au/GO with a halfwave potential of 0.90 V and a high mass activity of 0.526 A mgpd(-1) at 0.9 V, which both are higher than those of the commercial 40 wt% Pt/C and 20 wt% Pt/C. Meanwhile, the zinc-air battery catalyzed by Pd-Au/GO also exhibits a high peak power density up to 276 mW.cm(-2) and a long-term durability than those of Pt/C. The preparation of Janus Pd-Au nanoparticles with the strain effect mentioned in this paper may provide ideal path for the synthesis of other types of materials.