A novel CuAl2O4/MoS2/BaFe12O19 magnetic photocatalyst simultaneously coupling type I and Z-scheme heterojunctions for the sunlight-driven removal of tetracycline hydrochloride

Abstract

A novel CuAl₂O₄/MoS₂/BaFe₁₂O₁₉ (CAO/MS/BFO) magnetic photocatalyst simultaneously coupling type I and Z-scheme heterojunctions is synthesized using a wet chemistry method and heat treatment technology and exhibits high photocatalytic activity for the degradation of tetracycline hydrochloride (TC) under simulated sunlight irradiation. Various characterization techniques confirm that CAO/MS/BFO magnetic photocatalysts contain only cubic CAO, hexagonal MS and hexagonal BFO. By adjusting the content of BFO, not only the magnetic properties of the CAO/MS/BFO magnetic photocatalyst are regulated, but also the photocatalytic activity of the type I MS/BFO photocatalyst is improved. The photocatalytic activity of the CAO/MS/BFO magnetic photocatalyst increases first and then decreases as the BFO content, remanent magnetization (M_r), saturation magnetization (M_s) and coercivity (H_c) increases due to the combined effects of magnetothermal conversion and magnetic response characteristics. The CAO/MS/BFO magnetic photocatalyst demonstrated high photocatalytic activity with a degradation percentage of 95% at a catalyst content of 1 g L⁻¹, drug concentration of 100 mg L⁻¹ and pH of 11. The free radical verification experiment, liquid chromatography-mass spectrometry (LC-MS) analysis and toxicity analysis confirmed the role of free radical, degradation pathway and intermediate product toxicity of CAO/MS/BFO magnetic photocatalyst in the degradation of TC. A new photocatalytic mechanism of CAO/MS/BFO magnetic photocatalyst simultaneously coupling type I and Z-scheme heterojunctions is proposed based on energy band theory and experimental results. The design of this new photocatalyst provides a new idea for the development of other similar photocatalysts.