Enhanced photocatalytic activity of magnetically recyclable spherical Fe3O4/Cu2O S-scheme heterojunction

In this study, magnetically recyclable spherical Fe3O4/Cu2O particles comprising S-scheme heterojunctions were prepared by a simple hydrothermal approach using n-type semiconductor Fe3O4 as precursor and p-type semiconductor Cu2O. A Fenton-like system was thus constructed via the addition to Fe3O4/Cu2O of hydrogen peroxide. A rhodamine B (RhB) solution was used to simulate polluted wastewater, and photocatalytic RhB removal experiments were conducted under visible light irradiation. Powder X-ray diffractometry, vibrating-sample magnetometry, nitrogen adsorption-desorption, transmission electron microscopy, and X-ray photoelectron spectroscopy experiments were conducted to characterise Fe3O4 and Fe3O4/Cu2O composite. The band gap of Fe3O4/Cu2O was 1.76 eV, narrower than that of Fe3O4 (2.14 eV). The effects of the pH, sample dosage, hydrogen peroxide concentration, and RhB initial concentration on RhB removal were investigated. According to evidence, under the optimum reaction conditions, the RhB removal rate was 99.4%. The Fe3O4/Cu2O composite exhibited good photocatalytic efficacy even after four cycles of testing. Based on the results of free radical capture experiments, hydroxyl radicals and holes cooperated as main reactive species in the photocatalytic system. The Fe3O4/Cu2O photocatalyst can be easily removed based on magnetism, and it has been proven to be very effective for the degradation of RhB under both UV and visible light irradiation.