Applied Surface Science, Vol.430, 380-389, 2018
Carbon vacancy-induced enhancement of the visible light-driven photocatalytic oxidation of NO over g-C3N4 nanosheets
g-C3N4 (gCN) with carbon vacancy has been extensively investigated and applied in (photo) catalysis. Engineering the carbon vacancy in gCN is of great importance, but it remains a challenging task. In this work, we report for the first time the fabrication of gCN with carbon vacancy (C-v-gCN) via thermal treatment of pristine gCN in CO2 atmosphere. The photocatalytic performance of C-v-gCN is evaluated on the basis of NO oxidization under visible light irradiation (lambda > 400 nm) in a continual reactor. The successful formation of carbon vacancy in gCN is confirmed through electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). The photocatalytic oxidation removal rate of NO over C-v-gCN is 59.0%, which is two times higher than that over pristine gCN (24.2%). The results of the quenching experiment show that superoxide radicals (O-2(center dot-)) act as the main reactive oxygen species, which is responsible for the oxidation of NO. The enlarged BET surface areas and negatively shifted conduction band (CB) potential enhance the photocatalytic activity of Cv-gCN, which facilitates the efficient electron transfer from the CB of Cv-gCN to the surface adsorbed oxygen, resulting in the formation of O2(center dot-) that can oxidize NO. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Carbon vacancy;g-C3N4;Thermal etching;CO2;NO oxidation