Electrophoresis-driven AIE luminogens encapsulated within silica isoporous membrane for acid vapor sensing

Acid vapors emitted by chemical industries pose an increasing threat to public health. The development of a cost-effective sensor for the on-site and real-time monitoring of environmental acid vapor is of great significance. Aggregation-induced emission (AIE) luminogens overcome the aggregation-caused quenching effect and exhibit intense fluorescence when supported in the solid matrices. Silica isoporous membrane (SIM), characterized by vertically ordered nanochannels, holds great promise as a platform for encapsulating AIE luminogens and enabling gas sensing applications. The SIM containing surfactant micelles was prepared on an ITO electrode to obtain the M-SIM/ITO, and Tetrakis(4-carboxyphenyl)ethylene (TCPE) was employed as the investigated AIE luminogen. Upon application of positive potential, the negatively charged TCPE molecules were driven into the vertically ordered nanochannels, resulting in observable AIE fluorescence. By investigating the electrophoresis conditions such as TCPE charge, nanochannel microenvironment, and driving electric field, the AIE mechanism within the nanochannels was elucidated. The fluorescence of TCPE@M-SIM/ITO exhibited high sensitivity towards acid vapor and displayed reversible changes during the absorption and desorption processes. This behavior can be attributed to the SIM's strong absorption capability towards acid vapor as well as the reversible conversion of acid vapor on TCPE aggregates. This work presented an innovative methodology for studying luminophores within an orderly nanoconfined space, leading to a new perspective on the AIE mechanism.