Visible-light-assisted generation of high-valent iron-oxo species anchored axially on g-C3N4 for efficient degradation of organic pollutants

As highly active species, in theory, hydroxyl radicals ((OH)-O-center dot) can move freely and destroy almost all organic compounds, including catalysts with a conjugate structure. Therefore, a system that can generate oxidative species with a high activity, but where the active species is anchored to avoid autooxidation, is urgently required. In this work, we fabricated a novel visible-light-assisted advanced oxidation process based on high-valent iron species (Fe(IV)=O) over graphitic carbon nitride (g-C3N4) that was coordinated to iron hexadecachlorophthalocyanine (FePcCl16) through imidazole ligands (IMD). Under visible-light excitation, the phthalocyanine ring of the g-C3N4-IMD-FePcCl16/hydrogen peroxide (H2O2) can be motivated to an excited state FePcCl/(16)*, in which active H2O2 and the generation of anchored Fe(IV)=O species are used for the degradation of carbamazepine (CBZ). Because the molecular movement of transient Fe (IV)=O species is restricted, the possibility of oxidative collision is minimized, which provides good stability. An analysis of the electron paramagnetic resonance, gas chromatography/mass spectrometry, photoluminescence spectra, periodic on/off photocurrent density response and the photo-assisted catalytic active experiments, indicates that the rapid generation of Fe(IV)=O species occurs as the catalyst contacts the H2O2, which inhibits the conduction-band electrons of the g-C3N4 from reacting with H2O2 and generating (OH)-O-center dot. This study provides insight into the construction of suitable structures that will enhance visible-light-assisted catalytic oxidation activity and allow for the fabrication of an anchored highly active species. (C) 2017 Elsevier B.V. All rights reserved.