Self-assembled Au nanoparticles network thin films at air-water interface and their SERS properties

In this work, Au nanoparticles (AuNPs) network structures were fabricated by the self-assembly method at air-water interface, and the continuous AuNPs network thin films with higher stability can be obtained by further growth at room temperature. The proposed approach does not require any inducer to assist the assembly of AuNPs. The formation mechanism of AuNPs network films was studied by changing the relative amount of HAuCl4 and AgNO3 and aging time, and it was found that the amount of AgNO3 was very important to the formation of AuNPs network structures. AgNO3 can promote the fusion of AuNPs and the formation of nano-chain, and could further evolve into a nano-chain network structure. A large area and good stability of Au nanoparticles network films were fabricated after further growth of gold nanoparticles by ascorbic acid reduction. Furthermore, the surface enhanced Raman scattering (SERS) activity of the as-prepared AuNPs network films was investigated by using 4-aminothiophenol (4-ATP) as the SERS probe molecule. Compared with unassembled AuNPs, the AuNPs network films showed enhanced SERS performance for 4-ATP.