Heterogeneous Z-scheme CuO/ZnO aerogel photocatalyst for photocatalytic degradation of organic dye

Background: Although photocatalysis is an effective and eco-friendly technique for the degradation of persistent organic pollutants, fabricating an efficient photocatalyst with high photocatalytic performance, low cost, and reasonable recyclability is a major problem. Methods: In this work, we synthesized Z-scheme CuO/ZnO aerogels (CuO/ZnO AG) via epoxide-triggered gelation and photo-deposition methods and used the materials as photocatalysts for the photocatalytic degradation of rhodamine B dye (RhB) in water. While the photodeposition of CuO on the surface of ZnO AG evidently decreased the recombination rate of electrons and holes, 20 wt. % was the optimum loading amount of CuO. Significant findings: Over 20 wt. % CuO/ZnO AG, complete degradation of RhB was achieved within just 20 min with the reaction possessing a pseudo-first-order rate constant (k) of 0.0274 min-1. It was revealed that although both hydroxyl (center dot OH) and superoxide (center dot O2-) radicals contributed to the performance of the photocatalytic system, the contribution of center dot OH radicals in degrading RhB was much higher than center dot O2-. Meanwhile, the reusability test showed that the material can be reused for the reaction for at least four runs without a significant decrease in photocatalytic activity.