Carbon nitride nested tubes with graphene as a dual electron mediator in Z-scheme photocatalytic deoxynivalenol degradation

This work reports a facile and generally feasible method to construct carbon nitride nested tubes with graphene by directly heating cyanamide and zinc oxalate inside an anodic aluminium oxide (AAO) template. The nested tubular structure just like the shape of Russian dolls with RGO as a dual electron mediator exhibits excellent charge separation efficiency and strong redox ability, thus showing excellent photocatalytic activity for degradation of pollutant deoxynivalenol under visible and UV light irradiation. Meanwhile, the effect of graphene (RGO) as a dual electron mediator for two interfaces in the Z-scheme ZnO/g-C3N4/RGO photocatalytic deoxynivalenol degradation system was demonstrated. The ESR and trapping experimental results confirmed that the introduction of graphene as a dual electron mediator changed the mechanism of the photocatalytic reaction from a traditional type-II process to a Z-scheme mechanism responsible for remarkable photocatalytic properties. Systematic studies on the electronic energy level structure, nested tubular structures within the Z-scheme ZnO/g-C3N4/RGO system, and photocatalytic performance have been carried out. Our findings will provide a novel approach toward the use of graphene as a dual electron mediator in the Z-scheme system as well as the role localization of graphene in the photocatalytic mechanism.