Graphitic carbon nitride (g-C3N4) is a promising photocatalyst for environmental protection but its development is greatly limited for its application in dark Fenton-like reactions due to its extremely low specific surface area and lack of suitable active sites. Herein, for the first time, graphitic carbon nitride with large surface area and abundant defect sites was developed by tailoring oxygen via a simple and green method without any templates, namely, the calcination-hydrothermal-calcination successive treatment of melamine. The structure of the catalyst was characterized using several technologies, including XRD, SEM, TEM, N2-physisorption, FT-IR, Raman spectroscopy and XPS. The results revealed that it possessed a large specific surface area (ca. 236 m2 g-1), while changes in its structural properties such as the formation of new defect sites and change in the content of nitrogen atoms were observed. These properties were beneficial for the in situ activation of H2O2 toward reactive oxygen species, as confirmed by the reactive oxygen species capturing experiments. Furthermore, various influencing factors were systemically investigated. The results clearly showed that the oxygen-doped g-C3N4 was light-independent and metal-free Fenton-like catalyst for the enhanced degradation of organic pollutants in wastewater. Compared to the pristine g-C3N4, the oxygen-doped g-C3N4 showed superior performance under various conditions such as broad pH range and excellent stability. Thus, this study provides a novel pathway for the treatment of organic pollutants in water.
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