Abstract
Semiconductor quantum dots have been recently employed as luminescent probes for the detection of hazardous nitroaromatic compounds. Despite the high sensitivity, such detection systems involve laboratory procedures and employ complex instrumentation. Here, we demonstrate the use of colloidal PbS quantum dots as the main component of a chemiresistor for the detection of nitroaromatic compounds. The proposed device is low-cost, reusable, and produces an electric signal that can be acquired with off-the-shelf electronic components. In this paper, we demonstrate the operation of the proposed device and we discuss its sensing mechanism. We also show the sensor’s response to nitrobenzene in the 65 ppb–16 ppm range, estimating a theoretical detection limit of 2 ppb.
Highlights
Detection of nitroaromatic compounds (NACs) vapor is essential for homeland security,[1] unrecovered land mines finding,[2] human health,[3] and environmental safety[4] since they are registered on the US Environmental Protection Agency’s (EPA) list of priority pollutants for environmental remediation.[5]
Gas sensors are a suitable technology to meet these needs, where the interaction of sensing materials with explosive molecules leads to observable outputs like a change in conductivity, color, or fluorescence.[13−15] In the last few years, many different approaches have been proposed for explosive sensing, employing a variety of materials.[16−19] Among all, sensors based on colloidal quantum dots (QD) have been widely investigated over the past few years as luminescent probes for the detection of a variety of analytes, including NACs
Gas sensors based on PbS QD have already been demonstrated, but there are no examples to date of QDbased chemiresistors for NAC detection.[29−34] In this article, we report on a novel and high-performance chemiresistive sensor based on PbS QD for the detection of traces of nitroaromatic explosives at room temperature
Summary
Detection of nitroaromatic compounds (NACs) vapor is essential for homeland security,[1] unrecovered land mines finding,[2] human health,[3] and environmental safety[4] since they are registered on the US Environmental Protection Agency’s (EPA) list of priority pollutants for environmental remediation.[5]. The majority of QD-based sensors are based either on photoinduced electron transfer (PET) or fluorescence resonance energy transfer (FRET) mechanisms In the former case, the interaction between electron-rich surface-functionalized QD and electron-withdrawing NACs’ nitro groups leads to the quenching of QD photoluminescence. Sensors based on the change of conductivity are potentially advantageous with respect to those based on photoluminescence quenching since they can be implemented in lowpower and low-cost electronics Their fabrication is suitable for integration with silicon technology. Sensor performance was evaluated through the sensor response (S), expressed in percentage, and calculated according to eq 1, where Ia and Ig are the initial current and its value after exposure to a given vapor concentration of the target gas, respectively. The recovery time is the time required to reach 10% of the total current change after purging the measurement chamber with clean air
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