Internal electric field and oxygen vacancies synergistically boost S-scheme VO/BiOCl-TiO2 heterojunction film for photocatalytic degradation of norfloxacin

Abstract

Sluggish interfacial dynamics and weak redox properties make the degradation of antibiotics by photocatalysts still a great challenge. Herein, constructing S-scheme heterojunction between BiOCl and TiO2 nanorod arrays (TNA) by hydrothermal method, and the synergistic effect of oxygen vacancies (VO) and Internal Electric Field (IEF) on improving the performance of the photocatalysts was revealed by adjusting the VO. The VO modified BiOCl-TiO2 (VBiTNA) exhibited excellent photocatalytic activities for norfloxacin, achieving a degradation efficiency of up to 90.2 % in just 60 min, and the rate constant was as high as 3.67 × 10-2 min−1. In addition, it also showed great photocatalytic degradation performance of NOR in a wide pH range, complex ionized water environment and real water source. The degradation intermediates and degradation pathway of NOR were predicted with LC-MS technology and Fukui function. Combined with free radical capture, electron paramagnetic resonance, relevant electrochemical testing, and DFT calculations reveals the mechanism of the enhanced photocatalytic performance of VBiTNA. The performance enhancement can be attributed to the expansion of the light absorption range, enhanced adsorption of O2 and effective activation to generate ·O2–, while improving the separation efficiency of electron-hole pairs and maintaining a strong redox capacity. This research focusing on VO and IEF mechanisms will help to advance the rational design of high-performance defective photocatalysts.