Enhanced photocatalytic activity of a hydrogen bond-assisted 2D/2D Z-scheme SnNb2O6/Bi2WO6 system: Highly efficient separation of photoinduced carriers.

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 SnNb2O6/Bi2WO6 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 SnNb2O6/Bi2WO6 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 SnNb2O6 (4.33 × 10-3 min-1), and Bi2WO6 (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 SnNb2O6/Bi2WO6 system is proposed, which is based on the ESR analysis and the DFT calculations.