Sensing aromatic pollutants in water with catalyst-sensitized water-gated transistor

Abstract

Some materials that are active heterogeneous catalysts for the breakdown of non-ionic aromatic solutes in water are found to act as potentiometric sensitizers for same solutes. As an example, here the aromatic water pollutant, benzyl alcohol, was sensed with a limit of detection below its potability limit of 19 μM. Our findings are rationalized on the grounds that both catalysis and sensing rely on adhesion of analyte/substrate on the sensitizer/catalyst. Specifically, a set of powdered transition metal-doped zeolites and related frameworks that catalyze the oxidation of waterborne aromatic pollutants were dispersed in phase transfer matrices. Matrices were introduced into water-gated thin film transistors that act as potentiometric transducers. Potentiometric sensing of non-ionic waterborne pollutants is limited to molecules with a ‘free’ molecular dipole, i.e., a dipole that is not locked in the molecular plane. The present work establishes an application for catalysts beyond catalysis itself. The use of catalysts as sensitizers is recommended for wider uptake and in reverse, to screen candidate catalysts.