Quantitative Time-Resolved Visualization of Catalytic Degradation Reactions of Environmental Pollutants by Integrating Single-Drop Microextraction and Fluorescence Sensing

Current methods for evaluating catalytic degradation
reactions
of environmental pollutants primarily rely on chromatography that
often suffers from intermittent analysis, a long turnaround period,
and complex sample pretreatment. Herein, we propose a quantitative
time-resolved visualization method to evaluate the progress of catalytic
degradation reactions by integrating sample pretreatment [single-drop
microextraction, (SDME)], fluorescence sensing, and a smartphone detection
platform. The dechlorination reaction of chlorobenzene derivatives
was first investigated to validate the feasibility of this approach,
in which SDME plays a critical role in direct sample pretreatment,
and inorganic CsPbBr3 perovskite encapsulated in a metal–organic
framework (MOF-5) was utilized as the fluorescent chromogenic agent
(FLCA) in SDME to realize fast in situ colorimetric detection via
the color switching from green (CsPbBr3) to blue (chlorine
lead bromide, inorganic CsPbCl3 perovskite). The smartphone,
which can calculate the B/G value of FLCA, serves as a data output
window for quantitative time-resolved visualization. Further, a [Eu(PMA)]n (PMA= pyromellitic acid) fluorescent probe
was constructed to use as an FLCA for the in situ evaluation of cinnamaldehyde
and p-nitrophenol catalytic reduction. This approach
not only minimizes the utilization of organic solvents and achieves
quantitively efficient time-resolved visualization but also provides
a feasible method for in situ monitoring of the progress of catalytic
degradation reactions.