A facile approach for the synthesis of Z-scheme photocatalyst ZIF-8/g-C3N4 with highly enhanced photocatalytic activity under simulated sunlight

Abstract

In this study, ZIF-8-modified g-C₃N₄ (ZIF-8/g-C₃N₄) composites were successfully synthesized by hydrothermal reaction. The properties of the ZIF-8/g-C₃N₄ composites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy. The results indicated that the ZIF-8 grew on the surface of the g-C₃N₄, forming closely contacted interfaces between the ZIF-8 and the g-C₃N₄ component. The photocatalytic performance of the ZIF-8/g-C₃N₄ composites was evaluated through the photodegradation of Rhodamine B (RhB). The results showed that 99.8% of RhB was degraded by the ZIF-8/g-C₃N₄ composite with 3 wt% of ZIF-8 in 60 min under simulated sunlight, which was much higher than that of pure g-C₃N₄ and ZIF-8. This highly enhanced photocatalytic activity of the ZIF-8/g-C₃N₄ composites can be mainly attributed to strong interfacial interaction promoting the photo-generated electron–hole separation and migration. The results of radical scavenger experiments showed that ˙O₂⁻ and h⁺ were the dominant reactive species in the photocatalytic reaction. In addition, the ZIF-8/g-C₃N₄ composites showed excellent stability over several reaction cycles. Finally, a possible Z-scheme photocatalytic mechanism was proposed based on the experimental results.