Passive sampling systems (PASs) are a low cost strategy to quantify Hg levels in air over both different environmental locations and time periods of few hours to weeks/months. For this reason, novel nanostructured materials have been designed and developed. They consist of an adsorbent layer made of titania nanoparticles (TiO2NPs, ≤25 nm diameter) finely decorated with gold nanoparticles. The TiO2NPs functionalization occurred for the photocatalytic properties of titania-anatase when UV-irradiated in an aqueous solution containing HAuCl4. The resulting nanostructured suspension was deposited by drop-casting on a thin quartz slices, dried and then incorporated into a common axial sampler to be investigated as a potential PAS device. The morphological characteristics of the sample were studied by High-Resolution Transmission Electron Microscopy, Atomic Force Microscopy, and Optical Microscopy. UV-Vis spectra showed a blue shift of the membrane when exposed to Hg0 vapors. The adsorbed mercury was thermally desorbed for a few minutes, and then quantified by a mercury vapor analyzer. Such a sampling system reported an efficiency of adsorption that was equal to ≈95%. Temperature and relative humidity only mildly affected the membrane performances. These structures seem to be promising candidates for mercury samplers, due to both the strong affinity of gold with Hg, and the wide adsorbing surface.

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Abstract. The combination of the affinity of gold for mercury and nanosized frameworks has allowed for the design and fabrication of novel kinds of sensors with promising sensing features for environmental applications. Specifically, conductive sensors based on composite nanofibrous electrospun layers of titania easily decorated with gold nanoparticles were developed to obtain nanostructured hybrid materials capable of entrapping and revealing gaseous elemental mercury (GEM) traces from the environment. The electrical properties of the resulting chemosensors were measured. A few minutes of air sampling were sufficient to detect the concentration of mercury in the air, ranging between 20 and 100 ppb, without using traps or gas carriers (LOD: 1.5 ppb). Longer measurements allowed the sensor to detect lower concentrations of GEM. The resulting chemosensors are expected to be low cost and very stable (due to the peculiar structure), requiring low power, low maintenance, and simple equipment.

<p><strong>Abstract.</strong> The combination of gold affinity for mercury with nanosized frameworks has allowed to design and fabricate novel kinds of sensors with promising sensing features for environmental applications. Specifically, conductive sensors based on composite nanofibrous electrospun layers of titania easily decorated with gold nanoparticles were developed to obtain nanostructured hybrid materials, capable of entrapping and revealing GEM traces from environment. The electrical properties of the resulting chemosensors were measured. Few minutes of air sampling were sufficient to detect the concentration of mercury in the air, in the range between 20–100 ppb, without using traps or gas carriers (LOD ~ 1.5 ppb). Longer measurements allowed the sensor to detect lower concentrations of GEM. The resulting chemosensors are expected to be low-cost, very stable (due to the peculiar structure), and requiring low power, low maintenance and simple equipment to work.</p>

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