Spontaneous Formation of Two-Dimensional Gold Networks at the Air−Water Interface and Their Application in Surface-Enhanced Raman Scattering (SERS).

Two-dimensional (2-D) gold networks were spontaneously formed at the air−water interface after HAuCl4reacted with fructose at 90 °C in a sealed vessel, in a reaction in which fructose acted as both a reducing and a protecting agent. Through fine-tuning of the molar ratio of HAuCl4to fructose, the thus-formed 2-D gold networks can be changed from a coalesced pattern to an interconnected pattern. In the coalesced pattern, some well-defined single-crystalline gold plates at the micrometer-scale could be seen, while in the interconnected pattern, many sub-micrometer particles and some irregular gold plates instead of well-defined gold plates appeared. It is also found that the 2-D gold networks in the form of an interconnected pattern can be used as substrates for surface-enhanced Raman scattering (SERS) because of the strong localized electromagnetic field produced by the gaps between the neighboring particles in the 2-D gold networks. [ABSTRACT FROM AUTHOR]