Structural Regulation of PdCu₂ Nanoparticles and Their Electrocatalytic Performance for Ethanol Oxidation

Two types of PdCu₂ nanoparticles were prepared through one-pot synthesis and a two-step reducing process, named as PdCu₂-1 and PdCu₂-2, respectively. The morphology and structure of as-prepared samples were investigated by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and inductively coupled plasma-optical emission spectrometry. Results showed that more Pd atoms were buried in the inside of PdCu₂-1, whereas more available Pd sites were distributed on the surface of PdCu₂-2. The electrochemical measurements indicated that both PdCu₂-1 and PdCu₂-2 nanoparticles showed a higher electrocatalytic activity than that for pure Pd nanoparticles. In particular, PdCu₂-2 predictably exhibited a better stability and durability as well as a lower onset potential and a higher catalytic current density than that of PdCu₂-1 toward ethanol oxidation in alkaline media. On the basis of these studies, the formation mechanisms of both the PdCu₂ catalysts and the relationship between their structure and properties were discussed in this paper.