Direct 2D/2D Z-scheme SnNb2O6/ZnO hybrid photocatalyst with enhanced interfacial charge separation and high efficiency for pollutants degradation

The development of high-efficiency heterostructure photocatalysts is an attractive strategy for aquatic pollutants degradation. Herein, a novel 2D/2D Z-scheme heterojunction between SnNb 2 O 6 nanosheets and flower-shaped ZnO nanosheets was designed and fabricated through a simple two-step hydrothermal method. As expected, the obtained composite photocatalyst exhibits outstanding photodegradation efficiencies for RhB and phenol. The optimal reaction rate constant over 20%-SnNb 2 O 6 /ZnO heterostructure in RhB degradation is almost 15.03 and 3.95 times higher than pristine SnNb 2 O 6 and ZnO, respectively. Such an improved photocatalytic activity is mainly ascribed to the broader optical absorption and facilitated charge separation, which can be proved by various analytical methods. This designed composite also displayed excellent stability in four-cycle experiments. Additionally, a possible direct Z-scheme electron migration mechanism under an internal electric field was proposed with the aid of reactive species trapping experiments. This work provides a feasible strategy to obtain high-performance photocatalysts and might inspire   a new perspective in the design of other 2D/2D Z-scheme heterojunctions for environmental purification.