Comparative study on photocatalytic activity: Ni ferrite/Mg ferrite vs. Z-scheme Ni ferrite/silver/Mg ferrite heterojunction under solar radiation

Abstract

This study investigates the photodegradation efficiency of core/shell structures comprising NiFe2O4/MgFe2O4 (NiF/MgF) and Z-scheme NiFe2O4/Ag/MgFe2O4 (NiF/Ag/MgF) heterojunctions for Methylene Blue dye degradation. In this study, solar radiation was used as a source of excitation. X-ray diffraction analysis reveals an increase in particle size and micro-strain for NiF/MgF and NiF/Ag/MgF, confirming the formation of core/shell structures. The NiF/Ag/MgF sample exhibits the highest magnetization, attributed to the RKKY magnetic interaction between NiF and MgF moments via the conduction electron of the Ag metal layer. Optical measurements indicate increased absorption coefficient and absorption bandwidth for core–shell structures. Photocatalytic activity measurements demonstrate that while bare MgFe2O4 MgF shows limited photodegradation efficiency, NiF/MgF and NiF/Ag/MgF heterojunctions significantly enhance photodegradation. The presence of the Ag metal layer in the NiF/Ag/MgF heterojunction reduces electron-hole pair recombination and enhances their separation, leading to exceptional photodegradation efficiency. These results highlight the significance of Z-scheme heterojunction configurations in augmenting photodegradation processes under solar radiation, offering notable economic advantages. Additionally, the high magnetization observed in the studied samples presents an opportunity for efficient waste material retrieval using a simple magnetic extraction method.