Synthesis of g-C3N4/ZnO composites with enhanced photocatalytic activity under visible light

Abstract

The g-C3N4/ZnO composites were synthesized by heating a mixture of urea and ZnO at 500 °C and denoted as g-C3N4/ZnO-w, where w is the weight ratio of urea/ZnO and equals to 3, 4 and 5. The obtained materials were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy ultraviolet-visible diffuse reflectance spectroscopy. The results showed that all g-C3N4/ZnO-w samples are composites of orthorhombic ZnO and g-C3N4. The photocatalytic activity of g-C3N4/ZnO-w samples was evaluated by degradation of methylene blue in water under visible light. Among them, g-C3N4/ZnO-4 sample exhibits the highest photocalalytic efficiency. The enhancement of photocatalytic activity of the g-C3N4/ZnO composites compared to single components g-C3N4 and ZnO was observed, which can be attributed to the reduction of combination rate of photogenerated electron - hole pairs in the composites.