Bioinspired catalytic generation of high-valent cobalt-oxo species by the axially coordinated CoPc on pyridine-functionalized MWCNTs for the elimination of organic contaminants

摘要

Graphical abstractBioinspired catalyst, axially coordinated cobalt phthalocyanine (CoPc) on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs-Py), has been synthesized for efficient and selective H2O2activation, where the high-valent cobalt-oxo species have been formed during the heterolysis of peroxide OO bond depending on the strong interaction between the coordinated N atoms in MWCNTs-Py and CoPc. The “anchored” high-valent cobalt-oxo species exhibit high reactivity and enough persistence during the oxidation, and such strategy provides a foundation on developing efficient and persistent catalytic system, in particular oxidation processes based on the complex catalysts with N4macrocycle structures.Display OmittedHighlights•Cobalt phthalocyanine (CoPc) was anchored on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs-Py).•CoPc-Py-MWCNTs were used for elimination of organic contaminants by selective H2O2activation.•High-valent cobalt–oxo species have been formed depending on the interaction between the MWCNTs-Py and CoPc.•Provide a new thought to develop persistent complex catalysts with N4 macrocycle structures.AbstractEnzymes have always been a source of inspiration for the design and improvement of catalysts. Many examples are occurring in hemeon-heme metalloenzymes with the generation of active high-valent metal-oxo intermediates that are controlled by the surrounding amino acids/protein and axial residue ligands, facilitating the efficient oxidation of substrates in biochemical processes. Here, the high-valent cobalt-oxo species have been formed during the heterolysis of H2O2activated by the bioinspired catalyst, axially coordinated cobalt phthalocyanine (CoPc) on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs-Py), characterized by ultraviolet–visible and X-ray photoelectron spectroscopy. Formation process of the active cobalt-oxo species has been further confirmed by electrospray ionization mass spectrometry analysis and the results from the density functional theory (B3LYP/6-311G) calculations. Such high-valent cobalt-oxo species exhibit high reactivity and enough persistence for the oxidation of the target substrate, C.I. Acid Red 1. The oxidation products are nearly biodegradable small molecules identified by ultra-performance liquid chromatography/high-definition mass spectrometry. This strategy provides a foundation on developing efficient and persistent catalytic system, in particular oxidation processes based on the complex catalysts with N4macrocycle structures.