Photocatalytic degradation of dissolved organic matter in landfill leachate by heterostructural ZnO-rGO composite catalysts

The dissolved organic matter (DOM) in landfill pollutes not only the landfill and surroundings, but also the environment far away from the landfill by infiltrating into the soil and/or flowing on the ground surface. Developing an efficient photocatalyst to degrade DOM is an interesting topic. Herein, the catalysts composed of ZnO and reduced graphene oxide (ZnO-rGO) with different morphologies were fabricated with a two-step hydrothermal method. The phase composite and microstructure were analyzed, and the degradation efficiency of the DOM under ultraviolet light was investigated. Three kinds of ZnO-rGO composite catalysts with different morphologies were successfully synthesized, and rGO was coated on the ZnO surface to form heterostructural composite catalysts. The catalyst powders have similar Raman and FT-IR spectra, but have different specific surface areas and band gaps. The degradation efficiency of DOM by ZnO-rGO composites is higher than that of pure ZnO powder. Compared to pure ZnO, ZnO-rGO composite catalysts contain more oxygen vacancies and a narrower band gap, and the heterostructure is beneficial for accelerating electron separation, inhibiting electron recombination.

Automated summary

In this study, ZnO-rGO composite catalysts with different morphologies were successfully synthesized using a two-step hydrothermal method. The degradation efficiency of dissolved organic matter (DOM) under ultraviolet light was higher for ZnO-rGO composites compared to pure ZnO powder. The heterostructure formed by coating rGO on the ZnO surface was beneficial for accelerating electron separation and inhibiting electron recombination.