2D/2D materials have attracted extensive attention in the field of photocatalysis due to their large contact surfaces and short charge transfer distances. However, 2D/2D heterojunction materials, especially those that connect different materials together using strong chemical bonds, are still challenging to prepare. Herein, a novel hydrogen bond-assisted 2D/2D Z-scheme SnNb 2 O 6 /Bi 2 WO 6 system was successfully prepared using a facile hydrothermal method . The 2D/2D Z-scheme system increases the accessible area for charges and constructs interfacial electric fields, thereby reducing the barriers for electron transport and enhancing the photocatalytic activity . In addition, the electronic coupling of the surface hydrogen bonds can further enhance the interfacial electric fields, which offers a new route for lowering the interfacial potential barrier of the system. As expected, the hydrogen bond-assisted 2D/2D Z-scheme SnNb 2 O 6 /Bi 2 WO 6 system results in an outstanding improvement of the norfloxacin (NOR) photodegradation efficiency, and the degradation rate constant (4.06 × 10 −2 min −1 ) is 9 and 2 times higher than those of SnNb 2 O 6 (4.33 × 10 −3 min −1 ), and Bi 2 WO 6 (1.70 × 10 −2 min −1 ), respectively. Simultaneously, three differently degradation pathways for the degradation of NOR were proposed based on the degradation products that were identified. Finally, a fast charge transfer mechanism of the hydrogen bonds that are connected to the 2D/2D Z-scheme SnNb 2 O 6 /Bi 2 WO 6 system is proposed, which is based on the ESR analysis and the DFT calculations.
He Wang,Jie Yu,Xiaohui Zhan,Lei Chen,Yanping Sun,Huixiang Shi
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.
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