Shrinking gap between nanoparticles in gold nanofilms to enhance Surface-Enhanced Raman Spectroscopy performance investigated by both experimental and theoretical methods

Sensitive and reliable interfacial self-assembled nanomembranes are widely used for the detection of chemical contaminants in food and environment. This study developed a high-performance Surface-Enhanced Raman Spectroscopy (SERS) analytical platform by self-assembling Au nanoparticles (AuNPs) at the three-phase liquid–liquid interface. The assembled nanoparticles arrays were immersed in halogen ions solution and the nanoparticle gaps were further shrunk through electrostatic interactions, resulting in a large-scale array of closely packed nanoparticles. The average gap between adjacent nanoparticles was less than 3 nm, where dense SERS ‘hot spots’ were generated and used for highly sensitive detection. The homogeneity of the self-assembled nanoparticle arrays under different conditions was still guaranteed despite the reduced integration time and the number of times in the mapping face sweep of the Au arrays. The improved high-throughput fabrication of self-assembled nanoparticle arrays in this way holds great promise for the development of a sensitive and reliable SERS platform for chemical contaminant monitoring.