Fabrication of hollow Cu2O@CuO-supported Au–Pd alloy nanoparticles with high catalytic activity through the galvanic replacement reaction

Abstract

We report the synthesis of unique Au–Pd bimetallic alloy nanoparticles (NPs) supported on a hollow Cu₂O–CuO core–shell heterostructure via the galvanic replacement method, which represents the first example of Au–Pd alloy nanoparticles immobilized on hollow Cu₂O@CuO nanocubes. The morphological evolution can be controlled by the reaction time. The morphology, composition, and structure of the as-prepared Cu₂O@CuO/(Au–Pd) material are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), elemental analysis (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The size of the Au–Pd bimetallic NPs deposited onto the Cu₂O@CuO nanocubes is ca. 15 nm. These bimetallic NPs showed a high catalytic activity towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in water at room temperature. Significantly, the strong synergistic effect between Au and Pd, and the high specific surface area of Cu₂O@CuO enhance the catalytic efficiency. The catalytic system can be reused for several cycles without any obvious decay of the catalytic efficiency.