Novel Zn0.8Cd0.2S/g-C3N4 heterojunctions with superior visible-light photocatalytic activity: Hydrothermal synthesis and mechanism study

• Zn0.8Cd0.2S/g-C3N4 heterojunctions with intimate interface were successfully fabricated.
• These Zn0.8Cd0.2S/g-C3N4 heterojunctions exhibit enhanced photocatalytic activities.
• The enhanced activity can be due to the efficient photoinduced carrier separation.
• O2− were the main reactive species for the photodegradation of MB.
• The Zn0.8Cd0.2S/g-C3N4 heterojunctions have good stability.

A simple hydrothermal method was used to fabricate a novel series of heterostructured Zn0.8Cd0.2S/g-C3N4 photocatalysts. The photocatalytic activity of the Zn0.8Cd0.2S/g-C3N4 was evaluated by the degradation of methylene blue (MB) under visible light irradiation. The as-prepared heterostructured Zn0.8Cd0.2S/g-C3N4 heterostructures showed enhanced photocatalytic activity for the degradation of MB, with compared to the pure Zn0.8Cd0.2S and g-C3N4. An optimum photocatalytic activity was observed over 50 wt% Zn0.8Cd0.2S incorporated g-C3N4 nanocomposite. The superior photocatalytic performance of Zn0.8Cd0.2S/g-C3N4 could be ascribed to its strong absorption in the visible region and low recombination rates of photoinduced electron–hole pairs because of the heterojunction formed between Zn0.8Cd0.2S and g-C3N4. We proposed the scheme for electron-hole separation and transport for the visible-light-driven Zn0.8Cd0.2S/g-C3N4 hybrid photocatalyst. It was found that the photodegradation of MB molecules is mainly attributed to the oxidation action of the generated O2− radicals and partly to the action of hvb+ via direct hole oxidation process.

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