Layered assemblies of single crystal gold nanoplates: Direct room temperature synthesis and mechanistic study

Layered assemblies of single crystal gold nanoplates are directly synthesized in large scale by simply adding aniline to HAuCl4-HCl aqueous solution at room temperature, without the need of extra capping agent or surfactant. In this approach, the large amount of Cl-, the oxidative etching by the O-2/Cl- pair, the protonation of aniline, and the mild reaction temperature cocontribute to greatly slow up the reduction process of AuCl4- for facilitating the formation of these anisotropic gold nanostructures. The as-synthesized layered assemblies consist of inseparable gold nanoplates interconnected via steps between layers, which are confirmed by SEM and TEM. Moreover, these layered assemblies are further characterized by EDX, SAED, FT-IR, XRD, and UV-vis-NIR, respectively. The effects of different synthetic parameters on the shape and size of the final gold product are investigated. On the basis of a series of experimental results, it is revealed that in situ produced polyaniline with rigidly straight chain molecular structure plays a key role in achieving these gold layered assemblies. The possible growth mechanism is also proposed.