Magnetic Fe₃O₄-Supported Gold Nanoflowers with Lattice-Selected Surfaces: Preparation and Catalytic Performance

Abstract

Nanoflowers (NFs)shape-controlled noble metal nanocrystalshave garnered significant attention because of their novel catalytic properties and applicability. In this paper, we report the preparation and catalytic performance of a magnetic Fe3O4-supported AuNF catalyst with a clean surface. The magnetically supported AuNFs were obtained by using magnetic Fe3O4 as the support. However, when nonmagnetic γ-Al2O3 was utilized as the support, the AuNFs did not exhibit a magnetic response. These supported AuNFs were utilized to catalyze the oxidation of 1-phenylethyl alcohol to acetophenone using air (1 atm) as the oxidant. The rate of formation of acetophenone using supported AuNFs was 8-fold higher than that of acetophenone using supported spherical Au nanoparticles of comparable size. In addition, the Fe3O4-supported AuNFs exhibited a higher rate of formation of acetophenone than the Al2O3-supported AuNFs. The Fe3O4-supported AuNFs were recovered using a magnet, and the recovered catalyst was reused under identical catalytic reaction conditions. The rate of formation of acetophenone using recovered Fe3O4-supported AuNFs remained unchanged, demonstrating no loss of catalytic activity.

Preparing Alumina-Supported Gold Nanowires for Alcohol Oxidation

“…The study of noble metal nanocrystals is very important in several areas of nanosciences, such as electrochemistry, electronics, magnetic storage sensing, and catalysis. − The properties of metal nanocrystals are strongly dependent on their sizes and shapes. ,, Therefore, an effective synthesis technique is essential to obtain nanocrystals with desired properties. Shape-controlled nanocrystals, such as nanowires (NWs) and nanoflowers, are easily synthesized by reducing the noble metal ions in a solution containing a surfactant, a polymer, or low molecular organic components as capping agents, which inhibit the precipitation of nanocrystals. − However, for gold nanoparticles (NPs), spherical NPs, such as decahedral, icosahedral, and truncated octahedral nanocrystals, are identified as stable structures because the surface area per volume of spherical NPs is lower than that of shape-controlled nanocrystals. , Recently, many studies have reported that NWs are prepared using the diffusion-limited aggregation method. ,− Such NWs tend to exhibit high catalytic activities compared to the original spherical NPs owing to the disordered state of the metal atoms within the aggregated domains, namely, grain boundaries, which often exhibit high catalytic activity. − To prepare NWs by this method, it needs high NP concentration because of the difficulty to aggregate NPs under low concentration (Figure ).…”