Sonochemical Synthesis of a Z‐Scheme CoFe ₂ O ₄ /TiO ₂ Heterojunction for Solar‐Light‐Driven Photocatalytic Degradation of Rhodamine B

A CoFe 2 O 4 /TiO 2 p–n heterojunction composite was synthesized via a facile sonochemical route and characterized using thermogravimetric analysis (TGA), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), and UV–visible diffuse reflectance spectroscopy (UV–Vis DRS). Additionally, textural properties were investigated using the Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. Photocatalytic activity was evaluated by monitoring RhB degradation under various operating conditions using a UV–vis spectrophotometer. The optimized CoFe 2 O 4 /TiO 2 composite exhibited outstanding performance, achieving over 99% degradation of RhB (10 mg.L − 1 ) within 300 min under visible light at neutral pH, without the addition of external oxidants. Kinetic analysis indicated that the process followed a pseudo‐first‐order model, with an apparent rate constant ( K app ) of 0.0160 min − 1 and a half‐life of 43.32 min, with photogenerated holes and superoxide radicals playing a major role in the degradation mechanism. The catalyst also maintained good performance over a wide pH range, which is advantageous for practical applications. The enhanced activity can be attributed to the effective coupling between CoFe 2 O 4 and TiO 2 , which improves visible‐light absorption and facilitates charge separation via a Z‐scheme heterojunction. In addition, the composite's magnetic properties enable easy recovery and reuse after treatment.