Large Au@Pd/PdOx core–porous shell nanoparticles as efficient ethanol oxidation electrocatalysts

Abstract

In this article, large Au@Pd core–porous shell nanoparticles (NPs) with diameters of between 20 and 60 nm were synthesized by the seed-mediated growth method. Cetyltrimethylammonium chloride, used as a surfactant and structure-directing agent, plays an important role in determining the morphology and nanoporous shell structure of Au@Pd core–porous shell NPs. The resulting size of the Au@Pd core–porous shell NPs can be readily tuned by varying the volume of the Au seeds. The Au@Pd core–porous shell NPs were further characterized by X-ray diffraction and X-ray photoelectron spectrophotometry. An ultrathin layer of PdO/PdO₂ is formed on the surface of the porous Pd shell, which has a significant effect on the electrochemical properties. The electrocatalytic ethanol oxidation performances of Au@Pd core–porous shell NPs of different sizes were subsequently investigated. The observed volcano-shaped trend in the high electrocatalytic activity is linked to the nanoporous structure of the Pd/PdO_x shell. The current research will further promote Pd-based nanocatalyst applications in direct-ethanol fuel cells.