Interfacial heterojunction-engineered magnetic alpha-Fe2O3@NiFe LDH@biotemplate catalyst for heterogeneous photocatalytic activated persulfate removal of organic pollutants

The integration of multiple degradation pathways in a single catalyst has been proposed as a promising strategy for environmental remediation. The successful transition process from MnO2 to alpha-Fe2O3 is used to prepare 1D/2D/3D alpha-Fe2O3 @NiFe LDH@diatomite (FENFD) nanocomposite for improving conversion efficiency during pollutant degradation. The effects of initial pH, pollutant concentration, persulfate (PS) dosage, and catalyst dosage on the degradation rate were systematically investigated. FENFD demonstrated favorable PS activation performance and high degradation efficiency for Rhodamine B, azo dyes, and tetracycline over a broad pH range. Comparative experiments with quenching catalytically active radicals and analysis of electron spin resonance (ESR) spectra reveal that the sulfate radical generated by PS photocatalytic activation has a synergistic effect with superoxide radical and hydroxyl radical to degrade pollutants. Biotemplate-diatomite effectively achieves the dispersion of magnetic nano Fe2O3 and LDH and increases light utilization. Meanwhile, density functional theory (DFT) calculations demonstrate that the in situ grow Fe2O3 @NiFe LDH heterojunctions can efficiently transform the interface band structure to inhibit the recombination of photogenerated electron-hole pairs. The stability and reusability of the magnetic nanocomposites were also evaluated, and the degradation efficiency reached 96.4% even after five cycles, which provides new insight into designing single catalysts with different degradation mechanisms.