Dielectric barrier discharge plasma-assisted construction of LDH containing multiple defects for photocatalytic degradation of tetracycline

Abstract

Defect engineering is an increasingly popular strategy for boosting photocatalytic activity. However, given the variety of defect types and their differential performance across various materials, it remains unclear that how different defects affect photocatalytic performance. Accordingly, a defective Layered double hydroxides (LDH) containing two different types of defects (bulk defects and point defects (oxygen vacancies)) are created by Dielectric Barrier Discharge (DBD) plasma treatment, which confirmed the presence of the defects using scanning electron microscope (SEM), Transmission Electron Microscope (TEM), and Electron Paramagnetic Resonance (EPR). As the DBD treatment time increases, the bulk defect and point defects (oxygen vacancies) also increase and the distribution of oxygen vacancies is more uniform. These defects work together to enhance the visible light absorption, and to separate electrons and holes effectively, leading to a significant reduction in impedance. Kelvin Probe Force Microscopy (KPFM) analysis shows that the material with double defects and a more uniform distribution of oxygen vacancies has more electrons accumulated on its surface, and the electron transfer rate inside the material is faster. The effectiveness of LDH-90 was 66% higher than LDH in the degradation of tetracycline in 80 min. The study also explored the active species and degradation pathways involved. Lastly, the impact of the two types of defects on the performance of LDH is demonstrated. This study offers a fresh strategy to build two types of defects for improving interfacial charge migration by DBD plasma treatment.