Preparation of Au@Pd Core–Shell Nanorods with <i>fcc</i>-2H-<i>fcc</i> Heterophase for Highly Efficient Electrocatalytic Alcohol Oxidation

Abstract

Controlled construction of bimetallic nanostructures with a well-defined heterophase is of great significance for developing highly efficient nanocatalysts and investigating the structure-dependent catalytic performance. Here, a wet-chemical synthesis method is used to prepare Au@Pd core-shell nanorods with a unique <i>fcc</i>-2H-<i>fcc</i> heterophase (<i>fcc</i>: face-centered cubic; 2H: hexagonal close-packed with a stacking sequence of "AB"). The obtained <i>fcc</i>-2H-<i>fcc</i> heterophase Au@Pd core-shell nanorods exhibit superior electrocatalytic ethanol oxidation performance with a mass activity as high as 6.82 A mg_Pd^-1, which is 2.44, 6.96, and 6.43 times those of 2H-Pd nanoparticles, <i>fcc</i>-Pd nanoparticles, and commercial Pd/C, respectively. The <i>operando</i> infrared reflection absorption spectroscopy reveals a C2 pathway with fast reaction kinetics for the ethanol oxidation on the prepared heterophase Au@Pd nanorods. Our experimental results together with density functional theory calculations indicate that the enhanced performance of heterophase Au@Pd nanorods can be attributed to the unconventional 2H phase, the 2H/<i>fcc</i> phase boundary, and the lattice expansion of the Pd shell. Moreover, the heterophase Au@Pd nanorods can also serve as an efficient catalyst for the electrochemical oxidation of methanol, ethylene glycol, and glycerol. Our work in the area of phase engineering of nanomaterials (PENs) opens the way for developing high-performance electrocatalysts toward future practical applications.