Metal-Free Enhanced Photocatalytic Activation of Dioxygen by g-C3N4 Doped with Abundant Oxygen-Containing Functional Groups for Selective N-Deethylation of Rhodamine B

Abstract

To develop highly efficient heterogeneous photocatalysts for the activation of dissolved oxygen is very interesting in the field of green degradation of organic pollutants. In the paper, oxygen atom doped g-C3N4 (O-g-C3N4) was prepared via a facile chemical oxidation of g-C3N4 by peroxymonosulfate. X-ray photoelectron spectroscopy analysis suggests the oxidative treatment of g-C3N4 by peroxymonosulfate evidently increased atomic percentage of oxygen on O-g-C3N4 surface to 6.9% as compared with 1.8% for g-C3N4. Meanwhile, the doped oxygen atom mainly existed as carbonyl and carboxyl groups. Optical characterization indicates the introduction of oxygen improved the response of O-g-C3N4 to visible light, and more obviously, separation of photo-generated h+-e−. 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) probe measurement indicates the formation of O2•− was dramatically enhanced through activation of dioxygen by photo-generated electrons in the O-g-C3N4 photocatalytic system. Through high performance liquid chromatography (HPLC) and Liquid chromatography–mass spectrometry (LC-MS) analysis, it was found rhodamine B (RhB) photocatalytic degradation by O-g-C3N4 followed step by step N-deethylation reaction pathways induced by the formed O2•−, rather than the non-selective decomposition of the chromophore in RhB by other radicals, such as hydroxyl radicals. This study provides a facile method to develop oxygen atom doped g-C3N4 photocatalyst, and also clarifies its photocatalytic activation mechanism of molecular oxygen for N-deethylation reaction of RhB.

Construction of ZnTiO3/Bi4NbO8Cl heterojunction with enhanced photocatalytic performance

“…In addition, the position of absorption peak shifted from 554 to 499 nm during photocatalytic reaction. This blue shift of absorption maximum is caused by the N-deethylation of RhB [21][22][23].…”

g-C3N4/dendritic fibrous nanosilica doped with potassium for photocatalytic CO2 reduction

“…Peak fitting of the spectra was performed using XPSPEAK 4.1 software. The relative positions of the valence band (E VB ) and conduction band (E CB ) against NHE were calculated from the XPS valence band spectra: 27 E VB against NHE is estimated using the following equation:…”

Copper loaded nitrogen-rich mesoporous carbon nitride as a highly efficient photocatalyst for selective oxidative cleavage of C(sp3)–C(sp3) bonds at room temperature under visible light

“…Clearly, PCN and Cu/PCN have a typical V shape isotherm and H3 shape hysteresis loop. 45,51 Moreover, PCN has a kind of mesoporous structure with 30 nm pore size. In addition, the content of Cu in Cu/PCN is determined to be 9.1% by ICP-AES, which is consistent with the amount of Cu introduced.…”