Preparation of a direct Z-scheme α-Fe2O3/MIL-101(Cr) hybrid for degradation of carbamazepine under visible light irradiation

A series of direct Z-scheme alpha-Fe2O3/MIL-101(Cr) hybrids were successfully prepared through a facile hydrothermal method in this work. And, the materials were characterized by some technologies including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption, photoluminescence (PL) spectroscopy, Ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (DRS) and electron spin resonance (ESR). The photocatalytic activities of the hybrids were evaluated by degradation of carbamazepine (CBZ) under visible light irradiation. It is found that 100% of CBZ was able to be removed after 180 min irradiation over the optimum alpha-Fe2O3 (0.3)/MIL-101(Cr) hybrid. The superior activity was engendered from good textural properties and the formation of a direct Z-scheme heterojunction in the hybrid. The decomposition process of CBZ and the formation of intermediate products were analyzed through liquid chromatography-tandem mass spectrometry (LC-MS) and a possible photodegradation pathway of the CBZ was proposed. Also, the possible mechanism for the photodegradation process was provided to illustrate the excellent performance. The work has paved a new way for the application of MOF materials in the design of efficient Z-scheme system for organic pollution degradation in wastewater.