Ionic Liquid-Guided One-Step Green Synthesis of Au–Pd Superbranched Trigonal Nanoframes and Their Highly Selective Hydrogenation of 4-Nitrostyrene

Developing a simple, environmentally friendly, and mild method to one-step prepare bimetallic nanoframes is pretty important but still technically challenging. In this paper, a simple and easy-to-operate ionic liquid (IL)-regulated protocol is proposed to fabricate Au–Pd superbranched trigonal nanoframes (STNFs) in water at room temperature. In the aqueous solution containing precursors (Na2PdCl4 and HAuCl4) and a reducing agent (ascorbic acid), a common IL 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) was used to guide the anisotropic growth and construction of Au–Pd STNFs, brightly showing green and energy-saving characteristics. Au–Pd STNFs take shape as unique two-dimensional (2D) trigonal frameworks containing multilevel orderly branches. It is found that [C8mim]Cl is crucial to the formation of Au–Pd STNFs. Owing to the unique structures, high specific surface areas, large freestanding sizes, and probably electronic effects between Au and Pd, Au–Pd STNFs-1 exhibit dramatically enhanced catalytic activity, selectivity, durability, and convenience for recycling in the 4-nitrostyrene hydrogenation reaction. Specifically, 4-nitrostyrene can be converted completely only within 5.0 min at 25 °C under atmospheric pressure, and the selectivity toward 4-nitroethylbenzene is as high as 100% and maintains good performance after five cycles. It is expected that well-constructed Au–Pd STNFs also display advanced potential in other applications.