Facile construction novel SnO2/NiFe2O4 Z-scheme heterojunctions with largely enhanced photocatalytic activities

Photocatalytic technology is promising in the wastewater treatment field due to its environmental friendliness and high degradation rate. Herein, a highly photocatalytic active magnetic composite SnO2/NiFe2O4 is successfully prepared through the hydrothermal and physical grinding method, and its structure and properties are analyzed using advanced characterization methods. The results indicate a significant improvement in the light absorption of SnO2 with the incorporation of NiFe2O4, thus significantly improving the utilization of light energy by the wide bandgap semiconductor SnO2. The SnO2 composite with 3% wt NiFe2O4 (hereafter, SN-3) demonstrates outstanding photocatalytic performance, achieving a 97.3% degradation rate of Rhodamine B (RhB) under visible light for 120 min, which is much superior to that of pure phase SnO2. Characterizations of SN-3 show a decrease in fluorescence peak intensity and a rise in photocurrent density compared with SnO2, suggesting a lower recombination of photogenerated electron-hole pairs in SN-3 and a greater separation efficiency. Meanwhile, the magnetization strength of 1.06 emu/g for SN-3 provides the possibility of recycling the material. In addition, the degradation process primarily involves the participation of superoxide radicals (<middle dot>O-2(-)) and hydroxyl radicals (<middle dot>OH) as the main active groups. Based on this, the possible photocatalytic mechanism is explored and explained. This study provides a strategy for novel and effective composite semiconductor fabrication and further use in dye wastewater treatment.