Refractive index versus coupling effects for naked and surfactant-coated Au nanoparticle films: Implications for selective detection of vapor-liquid analytes

DALFOVO, MARÍA C.; CHRISTIAN D'AMBROSIO; ARBOLEDA, DAVID MUÑETÓN; FIONA BRITTO; LUISINA SCARBOL; LESTER, MARCELO; INCHAUSSANDAGUE, MARINA E.; DIANA CARINA SKIGIN; IBAÑEZ, FRANCISCO J.

ACS Applied Nano Materials

ACS

Año: 2021

2574-0970

From a single dispersion of surfactant-coated Au nanoparticles (NPs), we can assemble colorimetric films of different thicknesses, organic contents, and structures. In this work, wedemonstrate how these variables play a fundamental role in determining what sensing mechanism predominates when these films are subjected to ethanol (EtOH), acetone (Ace), and toluene (Tol) solvents. Theoretical calculations, performed with the the Korringa−Kohn−Rostoker (KKR) model, agree very well with the experiments if we consider that thinner films with lesser organic/inorganic content (or no organic) offer more vacancies for the solvents to partition, leading to effective changes in the permittivity. Instead, thicker films with a more compacted structure suffer minimal changes in the effective permittivity (lesser vacancies), causing color changes mainly dominated by changes in the distance between the Au NPs. These films may be incorporated into a sensor array for improving selectivity toward the detection of vapor/liquid-phase analytes.