Photocatalytic activation of environmental-friendly and lowcost peracetic acid (PAA) is a “green” strategy for wastewater treatment. Herein, C 2 N 3 , an allotrope of g-C 3 N 4 , was prepared for the first time via a simple calcination. The C 2 N 3 /PAA/Vis system was used to degrade sulfamethoxazole (SMX) and inactivate E. coli . The SMX was completed removed within 70 min, and its degradation rate constant was 10 times that of g-C 3 N 4 /PAA/Vis system. The system showed excellent degradation performance under wastewater simulation experiments. Electrochemical and EPR experiments verified that C 2 N 3 acted as an electron donor under visible light, and its electrons were transferred to O 2 to produce O 2 – . PAA acted as another electron acceptor and accepted electrons to generate 1 O 2 via non-radical pathways. This work reveals that high–efficiency bifurcated electron transport processes enhanced the degradation of contaminants and provides a superior metal–free catalyst/matrix-material for further doping to improve the performance in other applications.
Haini Wu,Wei Wang,Fatang Tan,Xinyun Wang,Xueliang Qiao,Po Keung Wong
Metal-free g-C 3 N 4 semiconductor has been extensively utilized as green catalyst for visible-light-driven degradation of various organic contaminants. However, its application has been constrained due to its inherent shortcomings, including weak visible light adsorption, low specific surface area and high recombination rate of electron-hole pairs. Herein, a novel carbon nitride (C 2 N 3 ) photocatalyst was synthesized via a one-step calcination method utilizing 3-amino-1,2,4-triazole (3-AT) as precursor for the first time. Unlike widely reported two-dimensional carbon nitride materials, the obtained C 2 N 3 exhibited a granular-like morphology with relatively high specific surface area. Under visible light (λ > 420 nm) irradiation, C 2 N 3 exhibited an excellent photocatalytic activity for Rhodamine B (RhB) degradation, due to its stronger visible-light absorption, faster photogenerated electron-hole separation and easier charge transfer, surpassing that of the popular g-C 3 N 4 . After 5 cycles, the degradation efficiency of RhB still remained over 94 %, suggesting high stability and reusability. Moreover, the C 2 N 3 /Vis system had high adaptabilities to temperature, solution pH and organic pollutant, even in the presence of high concentration of common matrix species like Cl − , NO 3 − , SO 4 2 − and humic acid. •O 2 − and 1 O 2 were revealed to be the main reactive species generated in the C 2 N 3 /Vis system, a combination process of radical and non-radical pathways for organic degradation. This work developed a novel granular-like C 2 N 3 material for visible light photocatalysis, which showed an incredible potential in photocatalytic degradation of organic pollutants.
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