Nowadays, significant progress has been achieved in the detection of explosives, such as 2,4,6-trinitrotoluene (TNT). To detect TNT with high sensitivity and high selectivity, a lot of detection methods have been explored in the past two decades. Fluorescence based detection has the notable advantages of high sensitivity, simplicity and high selectivity for vapor phase nitroaromatic explosives at very low concentrations. However, most of the fluorescence sensing films suffer from the poor mechanical stability, poor diffusion of analyte vapors and thus long response time, multistep syntheses method, low quenching efficiency and poor selectivity. 

Researchers from Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences (XTIPC), designed and synthesized novel flexible PVP/Pyrene/APTS/rGO fluorescent nanonets to detect TNT vapor via a one-step electrospinning method for the first time. The functional fluorescent nanonets, which are highly stable in air, show an excellent quenching efficiency of 81% towards TNT vapor (<10 ppb) with an exposure time of 540 s at room temperature. Compared to the analogues of TNT, the PVP/Pyrene/APTS/rGO nanonets showed excellent selectivity in ppb level (Fig.1). 

Researchers found the excellent performance of the nanonets was ascribed to the synergistic effects induced from APTS and rGO. APTS could provide receptor sites for electron-deficient TNT molecules to create strong charged complexes, resulting in a more efficient electron transfer from pyrene to TNT molecules. RGO not only enables fast charge transfer, but also enables effective π–π stacking with pyrene and TNT, leading to the formation of extended conjugation of π electrons and efficient long-range energy migration along the PVP/Pyrene/APTS/rGO nanonets.  

The explored modification method opens up a brand new insight for sensitive and selective detection of vapor phase nitroaromatic explosives. 

The result has been published online in Nanoscale. This work was supported by the National Natural Science Foundation of China, the “Hundred Talent Program” of CAS, the International Scientific Cooperation Program of Xinjiang, and the “Xinjiang Talent Plan” etc.  

Fig.1 Flexible PVP/Pyrene/APTS/rGO fluorescent nanonets with good performance and high selectivity towards TNT vapor
（Image by XTIPC）