Phase transformation and microwave hydrothermal guided a novel double Z-scheme ternary vanadate heterojunction with highly efficient photocatalytic performance

Abstract

Semiconductor-based heteronanostructures with the high carriers-flow steering and high activity and stability in the visible-light-driven multicomponent photocatalytic system have been of great concern due to its long-standing demand in the wide application of environmental protection and energy conversion. However, the construction of ternary-component nanocrystals usally undergos multiple complex steps to restrict its application. In the work, we successfully report the facile design and synthesis of a novel double Z-scheme Zn3(VO4)2/Zn2V2O7/ZnO ternary heteronanostructure system (THS) via self-phase transition with heating on basis of the Zn3(OH)2V2O7·2H2O precursor in a low-cost microwave hydrothermal assistant, which exhibited excellent photocatalytic performances. In this case, the employment of Zn3(OH)2V2O7·2H2O as the heteronanostructure precursor is the key for fabricating the THS material, which not only boosted the interaction with its structure and but also maintained the mesoporous nanosheet structure. It has been proved that Zn3(OH)2V2O7·2H2O firstly lost it H2O and then the partial Zn3(VO4)2 underwent the self-phase transition process to produce Zn2V2O7 and ZnO (Zn3(OH)2V2O7·2H2O → Zn3(VO4)2 → Zn2V2O7 + ZnO), which obtained the double Z-scheme THS. Accordingly, the interfacial-dominated photocatalysis reactivities such as the removal of phenols and dyes were used as ideal experiments to verify the responsibility of the constructed double Z-scheme THS material that was equipped with the narrow band gap, intimate contact interface, the wide visible light absortion and more efficient charge transfer and separation for high visible-light photocatalytic reactivity and stable cycling. PL spectra, radicals trapping experiments and ESR tests confirmed that the nontraditional transport of photoinduced h+ and e− caused by double Z-scheme mechanism played an important role in the efficient removing the target pollutants. Such a synthetic approach maybe render double Z-scheme THS to advance the development for large-scale applications of the hetero-transition metal vanadates.