Enhanced photo-Fenton activity over a sunlight-driven ignition synthesized α-Fe2O3-Fe3O4/CeO2 heterojunction catalyst enriched with oxygen vacancies

Abstract

The use of catalysts with several degradation mechanisms has emerged as a promising technique for advanced water treatment. Herein, a ternary α-Fe2O3-Fe3O4/CeO2 nanocomposite is synthesized using a sunlight-driven ignition method for the photo-Fenton degradation of organic dyes under sunlight irradiation. The fabrication of the nanocomposite using this method facilitates the introduction of oxygen vacancies on its surface, which enables the occurrence of multiple degradation mechanisms. The oxygen vacancies prolong the photogenerated charge recombination and expedite the redox cycle between Fe3+/Ce4+ and Fe2+/Ce3+. The effective construction of the α-Fe2O3-Fe3O4/CeO2 heterojunction catalyst enriched with oxygen vacancies is confirmed using different powerful analytical techniques. α-Fe2O3-Fe3O4/CeO2 shows higher photocatalytic activity toward the degradation of methylene blue (MB) than CeO2, α-Fe2O3, and α-Fe2O3-Fe3O4, which can be attributed to the enhanced light absorption in the visible region along with the improved charge separation among the components of the heterojunction through the oxygen vacancies. An inspection of the sample in the presence of H2O2 reveals that the degradation of MB dye is enhanced by 2.6 times, confirming the photo-Fenton catalytic process. Photoluminescence and active species trapping experiments evidence the role of •OH, •O2−, and 1O2 in the degradation of the dye. A synergistic mechanical pathway is proposed to explain the improved photo-Fenton reaction of the synthesized heterojunction composites.