Porous Halide Perovskite–Polymer Nanocomposites for Explosive Detection with a High Sensitivity

Abstract

a field-based environment, is critical for homeland security and public safety.In practice, trained canines and spectroscopic techniques have both been used to detect explosive chemicals. However, trained canines are expensive. They can also be fatigued and are not suitable for continuous monitoring. [15] Ion mobility spectrometry has been one of the most used commercial spectroscopic tools to detect explosive chemi cals. [16] It has a high sensitivity ranging from picograms to nanograms. [16] However, due to its high cost and large size, it is usually used in a stationary setting such as a security checkpoint. Alternatively, fluorescence-based explosive detection can be applied in-field at a relatively low cost. The detection mechanism is based on fluorescence quenching of the fluorophores after absorbing particles and/or vapors of the explosives. [17] Trace amount detection has been realized in literature using conjugated polymers, [18,19] metal-organic frameworks (MOFs), [20] and luminescent quantum dots (QDs), [21] etc. as the fluorophores. Very recently, halide perovskites have also been studied as new alternative fluorophores. For instance, Aamir et al. prepared cesium lead bromoiodide (CsPbBr 2 I) microcrystals in dimethylformamide (DMF) and demonstrated their use for detecting nitrophenol explosives. [12] Muthu et al. used methylammonium lead tribromide (MAPbBr 3 ) nanoparticles in toluene and reported their photoluminescence (PL) quenching characteristics by adding 2,4,6-trinitrophenol. [11] Halide perovskites have the advantage of an easier synthesis process at room temperature and exhibit more intense fluorescence due to their ultrahigh PL quantum yield compared to conjugated polymers, MOFs, and luminescent QDs fluorophores. Furthermore, previous reports used suspensions of halide perovskite particles in a solvent. In a humid environment, these perovskites will inevitably undergo composition degradation and fluorescence decrease, thus leading to false responses in a field detection. [22] In this work, we report porous nanocomposites consisting of MAPbBr 3 nanocrystals embedded in a poly(vinylidene fluoride) (PVDF) polymer matrix. The composites have a pore size of 2-10 µm and a wall thickness of hundreds of nanometers. The high porosity facilitates the diffusion process of explosive chemicals to the fluorescent perovskite nanocrystals, and the hydrophobic PVDF polymer matrix inhibits the penetration of water and alcohol molecules into the composites. As a result, the nanocomposites show no fluorescence degradation upon A porous halide perovskite-polymer nanocomposite is developed using a freeze-drying process. Such a composite shows strong fluorescence quenching after exposure to explosive nitroaromatics, nitroamines, and nitrate esters with a sensitivity of a few nanograms. In addition, this composite is robust against moisture and solvents, showing negligible change in fluorescence intensities after submersion in water, alcohol, and acid, base, and salt solutions. Transient absorption spectroscopy st...

Molecularly imprinted nanocomposites of CsPbBr3 nanocrystals: an approach towards fast and selective gas sensing of explosive taggants

“…The exact sensing mechanism behind PL quenching is still controversial: some authors propose a charge transfer mechanism between the PVK NCs and the analyte, and other authors propose trap-state generation in PVK NCs. 38,39…”

It is an All‐Rounder! On the Development of Metal Halide Perovskite‐Based Fluorescent Sensors and Radiation Detectors

“…To understand the quenching mechanism against nitrophenol exposure, femtosecond transient absorption spectroscopy was performed for the CH 3 NH 3 PbBr 3 thin films with and without TNT exposure. [30] The ground state bleaching and excited state absorption of the CH 3 NH 3 PbBr 3 have shown fast decay at 540 nm within first picosecond and all other signals have shown decay between 1 ps and 6 ns. [31] Among these decay processes, the fast decay was attributed to the cooling of hot carriers, whereas, the delayed processes was the decay of exciton or carriers.…”

“…Shan et al [30] reported the trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and trinitroglycerin (TNG) explosives detection by using porous CH 3 NH 3 PbBr 3 -PVDF nanocompsite that is stable in water/isopropanol medium and showed no degradation on expoure to the water contents. The nanocomposite showed 4% PL quenching upon addition of 2 ng of TNT solution.…”

Miscellaneous and Perspicacious: Hybrid Halide Perovskite Materials Based Photodetectors and Sensors

“…Reproduced with permission. [ 144 ] Copyright 2018, Wiley‐VCH. h) Schematic of the solar‐powered tactile sensor.…”

“…Hao et al embedded MAPbBr 3 nanocrystals in a poly(vinylidene fluoride) (PVDF) polymer matrix via the freeze‐drying process, obtaining a porous nanocomposite that showed strong fluorescence quenching when exposed to various explosive compounds such as, 2,4,6‐trinitrotoluene (TNT), 1,3,5‐trinitroperhydro‐1,3,5‐triazine (RDX), and trinitroglycerin (TNG), with a high sensitivity of a few nanograms (Figure 15g). [ 144 ] The high porosity increased the specific surface area, thus enhancing the absorption and diffusion process of explosive chemicals toward the perovskite nanocrystals. Meanwhile, the PVDF polymer matrix prevented the penetration of water and alcohol molecules into the composites due to the hydrophobicity.…”