Au₃Pd₁ Nanodendrites with Hyperbranched Architectures: Green Synthesis at Room Temperature and Highly Selective Hydrogenation for 4-Nitrophenylacetylene

Abstract

Conceiving a simple, green, and mild one-pot route to grow and construct anisotropic bimetallic 3D architectures with multilevel structures and promising functions is highly desirable and technically important in many applications. Herein, a facile ionic liquid-modulated strategy is presented for the preparation of hyperbranched Au3Pd1 bimetallic nanodendrites (NDs) in aqueous solution at room temperature. To implement this protocol, HAuCl4 and Na2PdCl4 are used as precursors and ascorbic acid as a reductant, and a common ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) is utilized to direct the anisotropic growth of 3D Au3Pd1 NDs, which exhibits an eco-friendly feature. It is shown that the alloy Au3Pd1 NDs possess multilevel architectures, that is, primary 3D large flowers (with diameters of about 2.5–4.0 μm), secondary 2D leaves, tertiary symmetric branches, and quaternary symmetric petals. A series of factors influencing morphologies and properties of the products are investigated, and the results indicate that both [C4mim]Cl and Au/Pd atomic ratios are crucial to the formation of 3D Au3Pd1 NDs. Owing to the well-defined morphology and probable electronic effects between Au and Pd, the 3D Au3Pd1 NDs display high catalytic selectivity and good durability toward stepwise hydrogenation of 4-nitrophenylacetylene with a 100% conversion and 99.5% selectivity to 4-nitrostyrene in the first step and then 100% conversion from 4-nitrostyrene and 96.7% selectivity to 4-nitroethylbenzene in the second step. It is believed that the well-defined 3D Au3Pd1 NDs would also exhibit promising applications in other catalysis and eletrocatalysis applications.