PdAu alloyed clusters supported by carbon nanosheets as efficient electrocatalysts for oxygen reduction

Abstract

PdAu alloyed clusters supported on carbon nanosheets were prepared and employed as efficient electrocatalysts for oxygen reduction reaction (ORR). PdAu clusters protected by glutathione were synthesized, while the structure and composition of the alloys were tuned through the variation of Pd-to-Au ratio. The PdAu clusters were loaded into carbon nanosheets and calcined at elevated temperature. The protecting ligands were completely removed after calcination, and uniform hybrid materials were formed. The as-prepared nanocomposites were characterized by transmission electron microscopy (TEM), scanning tunneling electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) as well as other techniques. The composites demonstrated effective ORR activity in alkaline media. Among a series of samples, the composite with a metal mass loading of 30% and the ratio of Pd-to-Au (1:2) exhibited the highest activity, and its performance is comparable to that of commercial Pt/C, superior to PdAu clusters, carbon nanosheets as well as other supported alloyed samples, in terms of onset potential, diffusion limited current density as well as number of electron transfer. Notably, the long-term stability of the composite is markedly higher than Pt/C. The strategy can be extended for the preparation of other supported bi-metallic nanoclusters with controllable composition and optimized electrocatalytic activity for fuel cell applications.