Achieving ultra-trace analysis and multi-light driven photodegradation toward phenolic derivatives via a bifunctional catalyst derived from a Cu(i)-complex-modified polyoxometalate

In the field of water decontamination, the design of a new catalyst for sensitive detection and effective removal of toxic phenolic compounds are important and challenging. Herein, a new bifunctional Cu(i)-naphthalene-amide-complex-modified catalyst, [Cu-4(I)(L)(4)(SiW12O40)(H2O)(4)] (1, L = N,N'-bis(3-methylpyridin-yl)naphthalene-2,6-dicarboxamide), was obtained by incorporating [SiW12O40]4- clusters into the Cu-L 3D supramolecular framework. 1 can be used as a peroxidase-like enzyme to detect seven kinds of phenolic compounds (phenol, 4-chlorophenol, o-cresol, p-cresol, 4-nitrophenol, resorcinol and phloroglucinol), which has an "nM" level LOD, satisfactory selectivity, stability, and applicability in various water environments. Using 1 as the photocatalyst, the effects of different irradiation light sources (UV light, visible light, NIR light, full spectrum light, and sunlight) on the photocatalytic degradation of phenol were studied. Taking visible light as representative irradiation, the photocatalytic performance toward the above seven phenolic compounds was also investigated. The removal efficiencies by photocatalytic degradation of the above phenolic derivatives within a relatively short time are satisfactory. By photocurrent response experiments and electrochemical impedance spectroscopy, the corresponding relationships between the types of irradiation light sources and the degradation effect of catalysts on phenol under different excitation light sources were studied. The photocatalytic mechanisms were also investigated using radical trapping experiments, VB-XPS and Mott-Schottky plots in detail.