INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Chemiresistive sensing of volatile organic compounds with films of surfactant-stabilized gold and gold-silver alloy nanoparticles
Autor/es:
IBAÑEZ, FRANCISCO J.; ZAMBORINI, FRANCIS. P.
Revista:
ACS Nano
Editorial:
American Chemical Society (ACS)
Referencias:
Lugar: Washington; Año: 2008 vol. 2 p. 1543 - 1552
ISSN:
1936-0851
Resumen:
Here we describe the chemiresistive sensing of volatile organic compounds (VOCs) with films of chemically-synthesized ~4 nm diameter Au and AuAg alloy nanoparticles (NPs) stabilized by a surfactant, tetraoctylammonium bromide (TOABr).  The chemiresistive sensing properties were measured over a concentration range of 100 to 0.04% saturation for methanol (MeOH), ethanol (EtOH), 2-propanol (IPA) and toluene (Tol) vapor analytes and compared directly to the chemiresistive sensing properties of films of 1.6 nm diameter hexanethiolate (C6S)-coated Au monolayer-protected clusters (MPCs).  Films of TOABr-stabilized Au NPs exhibit the opposite response compared to those of C6S-coated Au MPCs, which is attributed to changes in ionic conductivity upon incorporation of VOCs into the film for the former as opposed to changes in electron hopping conductivity for the latter.  This leads to a decrease in resistance in the presence of VOCs for TOABr Au as opposed to an increase for C6S Au.  The TOABr Au sensors are more sensitive, especially for polar analytes, and have greater long-term stability compared to C6S Au.  The limit of detection (LOD) for films of TOABr-coated Au NPs is 3, 2, 12, and 37 ppm for IPA, MeOH, EtOH, and Tol, respectively, as compared to 106, 326, 242, and 48 for C6S Au.  Films of TOABr-stabilized AuAg alloy NPs exhibit the same type of response, but the sensitivity decreases dramatically with increasing Ag content, showing that the metal composition of the NPs in the film plays a role in the sensing properties, which has not been well-recognized in the literature.