The photocatalytic performance and mechanism of magnetically retrievable Z-scheme Cr2O3–Fe3O4/C hetero-nanostructure polyhedra

Abstract

In this study, Z-scheme Cr₂O₃–Fe₃O₄/C hetero-nanostructure polyhedra are prepared using the amine-functionalized metal–organic framework NH₂-MIL-101(Fe) as the precursor through a simple hydrothermal method and impregnation–calcination route. Systematic characterization was conducted on the phase structure, morphology, optical/electrochemical properties and the photocatalytic performance exhibited by the magnetic Cr₂O₃–Fe₃O₄/C samples. As observed from the results, Congo red (CR) degradation rates of the magnetic polyhedron-like Cr₂O₃–Fe₃O₄/C hetero-nanostructures under visible light are found to be nearly 1.86 and 1.21 times higher than those achieved by Cr₂O₃ and Fe₃O₄/C samples, respectively. Complying with the results achieved by the active specie tests, superoxide radicals could be the major active species in the CR photocatalytic degradation due to graphite carbon with high conductivity. On this basis, a model Z-scheme photogenerated carrier transfer system was developed. In the present paper, an approach for developing and designing Z-scheme hetero-nanostructure photocatalysts for purifying wastewater is presented.