Synthesis of shape-controlled Pd nanocrystals on carbon nanospheres and electrocatalytic oxidation performance for ethanol and ethylene glycol

Palladium nanocrystals (Pd NCs) on carbon nanospheres (CNS) are the most important electrocatalysts especially in a direct alcohol fuel cell (DAFC). The shape and size-controlled of Pd NCs are crucial to their electrocatalytic activity. For the first time, we focused on the effect of ultrasound irradiation time interval to build the morphology and size-controlled of Pd NCs. Notably, the functional groups (COO−, and SO3−) situated on the edges and surfaces of CNS act as an effective capping agent and supporting materials for the growth of various morphology of Pd NCs on CNS surface. In this case, there is no need for an extra stabilizer or reducing agent for the preparation of Pd NCs. The catalytic activity of various Pd-CNS nanocomposites was investigated systematically using an electrochemical workstation. The results have shown that small-sized Pd NCs with a spherical shape had an enhanced activity and stability for alcohol oxidation relative to those of hexagonal Pd NCs and commercial Pd/C. Especially, the spherical Pd-CNS show mass activity 1.6 and 2.8 folds higher than that of hexagonal Pd-CNS and commercial Pd/C, respectively, and significantly maintain high activities after 1000 cycles of intensive durability test.