Photocatalytically Decorated Au-nanoclusters TiO 2 Nanofibres for Elemental Mercury Vapor Detection

A smart nanofibrous material for adsorbing and detecting elemental mercury in air

“…However, the conductivity of the nanocomposite is lower than that of pure metal (gold) because the electron mean free path is greatly reduced due to the presence of the dielectric (the titania crystals). The electrical features, such as the reproducibility of the fabrication process, of this conductive device have been previously investigated by the authors (Macagnano et al, 2017(Macagnano et al, , 2015a, showing encouraging results for the development of a low-cost sensor for mercury detection. However, in spite of the high sensitivity (LOD: 2 ppt) of the sensor, a too-long response time was necessary to detect traces of Hg 0 , especially if compared to the monitoring instrumentation (Ghaedi et al, 2006;Sanchez-Rodas et al, 2010;Ferrua et al, 2007) commonly involved in GEM detection.…”

“…The calcination process caused a complete degradation of PVP with the formation of crystalline TiO 2 (anatase) and a significant shrinkage in the fiber dimensions (60-80 nm diameter; 5-40 nm grain size). By exploiting the photocatalytic properties of titania (anatase), a tunable decoration of fibers with gold nanoparticles could be achieved by dipping the fibrous mats in a proper aqueous solution (HAuCl 4 ; PVP) under UV light irradiation (Li et al, 2004;Macagnano et al, 2015a). The photocatalytic reaction was confirmed by the color change of the solution (reddish purple from light yellow; Fig.…”

“…Figure 6 depicts the current-voltage (I-V) curve of a chemosensor under a synthetic dry air flow. However, the curve shape was unaltered when air or nitrogen was flushed over the fibers (Macagnano et al, 2015a), suggesting that oxygen concentrations poorly affected the electrical properties of such a chemoresistor. The resistance value of the IDE coated with TiO 2 nanofibers before photocatalysis was too high at room temperature to contribute directly to the final current value.…”

“…Thus in a blend of other chemicals, this sensor has been designed as a relatively selective sensor able to greatly decrease the environmental disturbances, allowing the investigator or manufacturer to design and then implement easier strategies to prevent contamination from the environment (selective filtering systems or coatings). Among the common potential contaminants, the authors previously investigated water vapor influence (% RH) and reported no effects on the electrical signals (Macagnano et al, 2015a).…”

“…When designed, the resulting Hg adsorbent or absorbent material was expected to be suitable for novel Hg sensor fabrication, since a similar nanofibrous scaffold doped with AuNPs was described in the literature as a filtering system capable of adsorbing and removing Hg vapor from the environment with an efficiency of nearly 100 % (Yuan et al, 2012). In previous work (Macagnano et al, 2017(Macagnano et al, , 2015a, the authors reported a high sensitivity of the sensor capable of detecting up to dozens of ppt v despite the long time needed to reveal the analyte at these concentrations in air. In this work, the chance to apply the sensor in polluted sites and in real time has been presented and described.…”