Morphology Engineering of Au/(PdAg alloy) Nanostructures for Enhanced Electrocatalytic Ethanol Oxidation

Abstract Noble metal nanostructures are promising electrocatalysts with their performance determined by their size, shape, and architecture. This study reports the facile preparation of Au/(PdAg alloy) electrocatalysts with diverse architectures, including nanodumbbells, yolk/shell nanoframes, and yolk/shell nanoboxes, from Au nanorod core/Ag shell bimetallic nanostructures. The fine tuning of the nanostructure architecture is realized by combining galvanic replacement reaction, etching/growth, Ostwald ripening, and coreduction processes. The adding sequence of surfactants and Pd precursors, and the Ag shell thicknesses of the starting core/shell nanocrystals, determine the growth routines and therefore the architectures of the obtained Au/(PdAg alloy) nanostructures. Electrocatalytic performances of all Au/(PdAg alloy) nanostructures toward ethanol oxidation reaction (EOR) in alkaline are examined. Compared with the commercial Pd/C electrocatalyst, the nanodumbbells (Au₁₉Pd₁₉Ag₆₂) display 6.3 times higher specific activity and 4.25 times higher mass activity. The nanoframes (Au₁₄Pd₁₄Ag₇₂) are superior as well, with their specific and mass activities 4.4 and 5.5 times higher than those of the Pd/C electrocatalyst, respectively. The nanoboxes also show slight improvement in electrocatalysis. Moreover, the nanodumbbells exhibit greatly improved stability toward EOR in comparison to the Pd/C electrocatalyst. These results can enrich the manufacturing techniques of noble metal nanostructure catalysts and promote their development for fuel cell applications.