Toward Membrane-Free Amperometric Gas Sensors: An Ionic Liquid–Nanoparticle Composite Approach

Abstract

Room temperature ionic liquid (RTIL)–gold nanoparticle composites have been demonstrated to overcome a major obstacle for creating an extremely thin layer of RTIL on the surface of an electrode for membrane-free amperometric gas sensors. A combination of the advantages of RTILs and the superior catalytic effect of gold nanoparticles provides some new brillant abilities of RTIL–gold nanomaterial composites, which includes not only larger current and ultrafast response but also real diversity, morphology-dependent activity, and lower reduction potentials in contrast with conventional screen-printed carbon electrode (SPCE). Several ionic liquids with different viscosities and surface tensions, such as 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][NTf2]), 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide ([C4dmim][NTf2]), and 1-hexyl-3-methylimidazolium trifluorotris(pentafluoroethyl) phosphate ([C6mim][FAP]), and gold nanorods (GNRs) and and quasi-platonic gold nanoparticles (QPGNPs) have been chosen for the measurements. The response of the sensor was quantified by both cyclic voltammetry and chronoamperometry. Such sensors indeed possess the characteristics required for a really versatile, long-lived membraneless sensor.