Defect engineering of water-dispersible g-C3N4 photocatalysts by chemical oxidative etching of bulk gC3N4 prepared in different calcination atmospheres

In this study, water-dispersible graphitic carbon nitride (g-C 3 N 4 ) photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C 3 N 4 that was polymerized thermally in different calcination atmospheres such as air, CO 2 , and N 2 . The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C 3 N 4 , changing the photocatalytic degradation behavior of methylene blue (MB) and tetracycline hydrochloride (TCHCl) for water-dispersible g-C 3 N 4 . The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C = O groups that preferred substituting the C-NH x groups over bulk g-C 3 N 4 . In the oxygen-free N 2 atmosphere among the different calcination atmospheres, more C = O functional groups were generated on the defective edges of bulk g-C 3 N 4 , resulting in the highest N vacancy of the tri-s-triazine structure. During the successive chemical oxidation, S- or O-containing functional groups were introduced onto water-dispersible g-C 3 N 4 . The water-dispersible g-C 3 N 4 photocatalyst from the oxygen-free N 2 atmosphere (NTw) contained the most O- and S- functional groups on the g-C 3 N 4 surface. Consequently, NTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process, which was ascribed to the unique surface properties of NTw such as abundant functional groups on the defective edges and N-deficient property. ?? 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, water-dispersible graphitic carbon nitride (g-C3N4) photocatalysts were prepared by chemically oxidative etching of thermally polymerized bulk g-C3N4 in different calcination atmospheres. The different atmospheres influenced the physicochemical and optical properties of the photocatalysts and their photocatalytic degradation behavior. The water-dispersible g-C3N4 photocatalyst from the oxygen-free N2 atmosphere exhibited the highest photocatalytic activity.