Efficient fluorescent vapour sensing induced by ZnO buffer

Abstract

Fluorescent film sensors have been widely used in the detection and alarm of toxic and harmful gases such as explosives and drugs. However, its current development is limited by the complex design and synthesis of high-performance sensitive materials. Therefore, simple and effective methods that can improve the sensing performance of the existing fluorescent materials are severely demanded, which can further reduce the dependence on sensitive materials in fluorescent sensors. In this study, by simply growing or depositing ZnO film on the quartz substrate, enhanced sensing performance of the fluorescent sensor is realized. The sensing process between 4- (phenyl (4- (4,4,5,5-tetramethyl-1, 3,2-dioxaborolan-2-yl) phenyl) amino) benzaldehyde (OTB) probe molecules and H2O2 gas is effectively accelerated by utilizing the catalytic properties of ZnO buffer. Through mimicry, the reaction rate constant is increased 4.76 times, and the time required for 50% fluorescence quenching is reduced from 258 min to 80 min. In the film-based sensor, the time required for 50% fluorescence quenching is reduced from 531.7 s to 186.0 s. It is shown that zinc oxide buffers prepared by atomic layer deposition or hydrothermal method have similar effects for enhanced sensing capability. In addition, such a method is further verified to be effective for the detection of other two dangerous gas simulants, methamphetamine (MPEA) and diethyl chlorophosphate (DCP). Specifically, for MPEA and DCP sensing, the fluorescence enhancement ratio increases from 1.2 to 5 times to 2.7 and 18 times in the control group within 300 s and 20 s, respectively. Moreover, theoretical calculation and solution mimic experiments further reveal the mechanism of ZnO buffer for accelerated sensing is due to the catalytic activity of ZnO buffer for the reaction.