In-Situ Implantation of Bivo4 Qds into Ti-Based Metal-Organic Framework Photocatalyst for Efficient Wastewater Treatment

Abstract

A novel photocatalyst of BiVO4 QDs/NH2-MIL-125 was successfully obtained via deposition of BiVO4 in a Ti-based metal-organic framework (NH2-MIL-125) for the first time. The crystal structure, morphology and optical properties were investigated by XRD, SEM, TEM and diffuse absorption spectrum, respectively. The electrochemical performance was analyzed by transient photocurrent test and EIS test. The result of N2 adsorption-desorption isotherm suggests the porous structure and larger specific surface area for the sample of BiVO4 QDs/NH2-MIL-125. Notably, the sample of 1BiVO4 QDs/NH2-MIL-125 exhibited a higher photocatalytic activity in 30 mg/L RhB degradation experiment and the degradation rate constant of 1BiVO4 QDs/NH2-MIL-125 is 2.337×10-2 min−1 which is 4.2 and 5.4 times higher than that of NH2-MIL-125 and BiVO4 QDs respectively. The free radical trapping experiment demonstrates that h+ and ⋅O2− play the major contributions during the degradation process, which is further confirmed by the electron paramagnetic resonance. In addition, a possible Z-Scheme reaction mechanism was proposed based on band potential. The Z-Scheme heterojunction facilitates carrier migration without loss of photoelectron energy. It is expected that this work could promote the application of QD-MOF composites in the field of water treatment.

Keywords: BiVO4, Photocatalysts, Quantum dots, Z-Scheme, NH2-MIL-125