Construction of Fe3O4/ZnO heterostructure photocatalysts derived from Fe-doped ZIF-8 for enhanced photocatalytic degradation of tetracycline and hydrogen peroxide production

Abstract

This study focuses on the development of Fe₃O₄/ZnO heterostructures derived from Fe-doped ZIF-8 through a precipitation and thermal decomposition approach. Fe³⁺ ions were incorporated into the ZIF-8 framework to partially replace Zn²⁺ ions, facilitating the formation of Fe₃O₄ during calcination under air. Optical and structural characterization, including ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), confirmed the successful formation of crystalline heterostructures. These heterostructures exhibited extended visible-light absorption, a narrowed bandgap, and the formation of defect states, which improved charge separation and suppressed electron–hole recombination. The Fe₃O₄/ZnO heterostructures demonstrate enhanced photocatalytic performance for two critical applications: tetracycline (TC) degradation and hydrogen peroxide (H₂O₂) production under visible light irradiation. Among the tested materials, Fe-ZIF-8 calcined at 500 °C showed the highest photocatalytic efficiency, achieving 74.8% TC degradation within 2 h, with a rate of 8.21 × 10⁻³ min⁻¹. Additionally, it exhibited a significantly enhanced H₂O₂ production yield of 919.2 μM within 3 h of irradiation. Radical scavenging experiments identified superoxide radicals (˙O₂⁻) as the primary reactive species driving the photocatalytic reaction. These findings highlight the potential of ZIF-8-derived photocatalysts as efficient and promising materials for sustainable wastewater treatment and green chemical production.