ZnO nanowires as effective luminescent sensing materials for nitroaromatic derivatives

Abstract

We report on the efficient room-temperature photoluminescence (PL) quenching of ZnO in the presence of 2,4-dinitrotoluene (DNT) vapor and for concentration as low as 180 ppb. Compared to ZnO thin films, ZnO nanowires exhibit a strong (95%) and fast (41 s) quenching of the PL intensity in the presence of DNT vapor. Assuming that the PL quenching is due to a trapping of the ZnO excitons by adsorbed DNT molecules, Monte-Carlo calculations show that the nanometric dimensions as well as the better crystallographic quality (longer mean free path) of the ZnO nanowires result in an enhanced trapping process at the origin of the improved sensing properties of the nanowires. The results demonstrate the importance of nanostructures in improving the sensitivity of ZnO. The study also reveals the sensing capability of ZnO nanowires and paves the path towards the potential realization of low-cost sub-ppb nitroaromatic derivative sensors.

Transition‐Metal‐Doped p‐Type ZnO Nanoparticle‐Based Sensory Array for Instant Discrimination of Explosive Vapors

“…ZnO‐based gas sensors have been applied in many fields to detect trace analytes, such as, ethanol, urea, and TNT . A ZnO nanorod‐based chemiresistor sensor shows good sensitivity toward trace (down to few ppb) DNT and TNT molecules . However, the most leading ZnO nanostructure‐based chemiresistor explosive sensors only have limited responses, such as, 20% toward 60 ppb TNT vapor .…”

Synthesis of ZnO nanowires and impacts of their orientation and defects on their gas sensing properties

“…The first one, which corresponds to the high peak located at the lower wavelength (around 380 nm), is associated to the near-band edge emission of the material. This strong emission corresponds to the recombination of electrons from the minimum of the conduction band with holes of the valence band of the semiconducting ZnO 25,26 . Additionally, by zooming in the visible light region of the spectra (see the inset in Fig.…”

Nanophotonics: Energy Transfer towards Enhanced Luminescent Chemosensing

“…The sensing surface can be easily enlarged by coating the polymer layer on non-planar surfaces. The enlarged sensing surface leads to gain in sensitivity due to the increased probability of analyte adsorption [15]. The approach was tackled by Zhu et al whom showed that coating a FSP on arrays of aligned ZnO nanorods allowed for better response time and quenching efficiency while having higher polymer fluorescence when compared to a polymer layer coated on a standard quartz plate [16].…”

“…The growth process by which the ZnO thin films were obtained is detailed in [19]. It is important to stress that most of the fluorescent polymers which are used for explosive chemosensing applications are excited by UV-blue light [9,10,11,12,13,14,15,16,22]. Thus, ZnO is not only adequate for exciting the FSP studied herein, but also adequate for most of the studied FSPs.…”