CDs-BOC Nanophotocatalyst Activating Persulfate Under Visible Light for the Efficient Degradation of Typical PPCPs

Abstract

A new type of CDs-BOC photocatalyst was synthesized in a convenient two-step method of hydrothermal and calcination processes. Carbon quantum dots (CDs) were used to modify BiOCl nanosheets. The as-prepared nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL), which showed that CDs were successfully introduced. The absorption edge of 7% CDs-BOC nanocomposite was broadened to the visible light region (424 nm), and the charge separation efficiency was remarkably improved. To improve the degradation efficiency of organic pollutants, persulfate (PS) was also introduced into the system. Due to the excellent photocatalytic ability of the nanocatalyst, the photogenerated electrons can effectively activate the PS to produce more reactive oxidizing species (ROS). Under visible light (λ>420 nm) irradiation, 5 mg·L-1 acetaminophen (AAP) can be completely removed within 20 min. Via radical quenching experiments and electron paramagnetic resonance spectroscopy (EPR), the major ROS are determined to be·OH,·SO4-,·O2-, and h+, and the photo-degradation mechanism is proposed. The excellent photocatalytic performance of the CDs-BOC/PS system shows broad practical potential for wastewater treatment.