Hydrogen Bonds and In-situ Photoinduced Metallic Bi0/Ni0 Accelerating Z-scheme Charge Transfer of BiOBr@NiFe-LDH for Highly Efficient Photocatalysis.

ABSTRACT

For heterojunction system, the lack of stable interfacial driving force and definite charge transfer channel makes the charge separation and transfer efficiency unsatisfactory. The photoreaction mechanism occurring at the interface also receives less attention. Herein, a 2D/2D Z-scheme junction BiOBr@NiFe-LDH with large-area contact featured by abundant interfacial hydrogen bonds and a strong interfacial electric field (IEF) is synthesized, and in-situ photoinduced metallic species assisting charge transfer mechanism is demonstrated. The hydrogen bonds between O atoms from BiOBr and H atoms from NiFe-LDH induce a significant interfacial charge redistribution, establishing a robust IEF. Notably, during photocatalytic reaction, Bi0 and Ni0 are in-situ isolated from BiOBr and NiFe-LDH in heterojunction, which separately act as electron transport mediator and electron trap to further accelerate charge transfer efficiency up to 71.2%. Theoretical calculations further demonstrate that the existence of Bi0 strengthens the IEF. Therefore, high-speed spatial charge separation is realized in Bi0/BiOBr@Ni0/NiFe-LDH, leading to a prominent photocatalytic activity with a tetracycline removal ratio of 88.3% within 7 minutes under visible-light irradiation and the presence of persulfate, far exceeding majority of photocatalysts reported previously. This study provides valid insights for designing hydrogen bonding heterojunction systems, and advances mechanistic understanding on in-situ photoreaction at interfaces.