Fabrication of double Z-scheme photocatalyst BiOI/g-C3N4/CoFe2O4 with enhanced photocatalytic activity for tetracycline hydrochloride degradation

[Display omitted] The enhanced photocatalytic performance of BiOI/g-C3N4/CoFe2O4 benefits from the synergistic effect of increased visible light absorption, double Z-scheme charge transfer mechanism and layered structure. •Double Z-scheme BiOI/g-C3N4/CoFe2O4 was prepared to improve photocatalytic activity.•Strong absorption, double Z-scheme charge transfer and structure improve performance.•Degradation is divided into fast stage and slow stage due to slight photocorrosion. Double Z-scheme BiOI/g-C3N4/CoFe2O4 was prepared and used for tetracycline hydrochloride degradation under visible light. The degradation rate can reach 85.2% after 240 min. The enhanced photocatalytic performance benefits from the synergistic effect of increased visible light absorption, double Z-scheme charge transfer mechanism and layered structure. Slight photocorrosion of CoFe2O4 causes the degradation process to be divided into a fast stage and a slow stage. BiOI/g-C3N4/CoFe2O4 is still stable during the photocatalytic reaction.