The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction (ORR) kinetics in acid media. To improve ORR activity and utilization efficiency of Pd, an ideal catalyst should have ORR-favorable chemical environment, optimized geometric structure, and long periods of operation. In this work, we first synthesize a novel trimetallic Au@PdPb core-shell catalyst consisting of PdPb alloy nano-layers grown on the surface of ultrathin Au nanowires (NWs) by a two-step water-bath method. The Au@PdPb NWs have the merits of anisotropic one-dimensional nanostructure, high utilization efficiency of Pd atoms and doping of Pb atoms. Because of the structural and multiple compositional advantages, Au@PdPb NWs exhibit remarkably enhanced ORR activity with a high haIf-wave potential (0.827 V), much better than those of commercial Pd black (0.788 V) and bimetallic Au@Pd NWs (0.803 V). Moreover, Au@PdPb NWs display better electrocatalytic stability for the ORR than those of Pd black and Au@Pd NWs. This study demonstrates the validity of our approach for deriving highly ORR-active Pd-based catalysts by modifying their structure and composition.

Developing highly efficient bifunctional cathode and anode electrocatalysts is very important for the large-scale application of direct formic acid fuel cells. However, the high-cost and poor CO-tolerance ability of the most commonly used Pt greatly block this process. To increase the utilization efficiency and extend bifunctional properties of precious Pt, herein, coral-like Pt₃Ag nanocrystals are developed as an excellent bifunctional electrocatalyst through a facile one-pot solvothermal method. The formation mechanism of Pt₃Ag nanocorals has been elaborated well via a series of control experiments. It is proved that 1-naphthol serving as a guiding surfactant plays a key role in the formation of high-quality nanocorals. Thanks to the unique coral-like structure and alloy effects, the developed Pt₃Ag nanocorals present significantly enhanced electrocatalytic properties (including activity, stability and CO-tolerance ability) towards both the cathodic oxygen reduction and anodic formic acid oxidation, as compared with those of commercial Pt black and Pt-based nanoparticles. The present synthetic method can also be extended to fabricate other bimetallic electrocatalysts with unique morphology and structure.