Engineering of ZnO/Graphene Nanocomposite for Enhancing Visible Photocatalytic Ability

Herein, the visible light-photocatalytic performance of synthesized ZnO/Gr composite materials with different Gr content under various conditions, i.e., pH, dye concentration, and different scavengers (to understand the photocatalytic activity mechanism) is systematically investigated. Photocatalytic performance is evaluated with the degradation of methylene blue (MB) in solution under sunlight irradiation. The presence of graphene (Gr) in the ZnO/Gr composites shows enhanced photocatalytic activity compared to pure ZnO under natural sunlight illumination. The highest photodegradation efficiency of approximate to 94% when the content of Gr is 1 wt% in comparison to approximate to 76% for the pure ZnO, corresponding to reaction rate constants of 0.01038 and 0.00615 min(-1), respectively. Compared to recent publications, the degradation efficiency is high with relatively high dye concentration, low catalyst amount, and large solution volume. The enhanced visible light absorption and the reduction of bandgap value are attributed to the enhanced photocatalytic properties of the hybridized composite. Moreover, the investigation of the effect of scavenger substances shows that H2O2 strongly enhanced their photocatalytic ability, suggesting that holes (h(+)) contribute as the reactive agent in the photodegradation process.

Automated summary

This study systematically investigates the visible light-photocatalytic performance of synthesized ZnO/Gr composite materials with different Gr content under various conditions. The presence of graphene in the composites enhances their photocatalytic activity compared to pure ZnO under sunlight irradiation. The highest photodegradation efficiency is achieved when the content of Gr is 1 wt%, reaching approximately 94%. This enhancement is attributed to the increased visible light absorption and the reduction of bandgap value in the hybridized composite. The investigation of scavenger substances suggests that holes contribute as the reactive agent in the photodegradation process.