Controllable preparation of imine-based nanofilms towards ozone detection and removal

Developing affordable, robust and less cumbersome ozone sensing materials is of pivotal importance for on-site and at real-time ozone monitoring in air, but that remains a challenge. Herein, we report for the first time the highly controllable preparation of a new kind of imine-based nanofilms with commercially available tris(4-aminophenyl) amine (TAPA) and 4,4',4''-((1,3,5-Triazine-2,4,6-triyl)tris(oxy))tribenzaldehyde (TOH-CHO) as the building blocks and their applications in the fast, sensitive detection and efficient removal of the analyte. The nanofilms as prepared are highly flexible and adaptive to substrates of very different properties and morphologies. In addition, the thickness of the nanofilms can be fine-tuned via variation of the precursor concentration. Ozone sensing and removal were realized by cumulative adsorption and decomposition accompanied with color change, where the nanofilms can be fully recovered via ammonia purging. Mechanism studies revealed that the high sensing and removing performance may originate from the protonation of imine bonds within the nanofilms. Further studies demonstrated that the sensing is highly selective and shows an experimental detection limit lower than 0.7 ppm. Moreover, visualized sensing of ozone in real-life scenarios was also realized via utilization of a test strip based on the nanofilms.