Self-assembly of nanoflower-like MIL-125(Ti)/Bi2O2CO3 hierarchical tandem heterojunctions for enhanced visible-light degradation of antibiotic contamination

Abstract

A high-efficiency photocatalytic composite with nano-flower-like structure was self-assembly constructed with Bi2O2CO3 as the main body to solve the problem of antibiotic pollution. Considering the high surface area and porous structure of MOFs, solvothermal method was used to introduce the porous band-matched n-type semiconductor MIL-125 into Bi2O2CO3 compound to construct a Self-assembly hierarchical tandem heterojunction, the tight binding of MIL-125(Ti) nanoparticles and Bi2O2CO3 nanoparticles facilitated charge transfer and separation under illumination. In the photocatalytic degradation experiment, the concentration of tetracycline was 20 mg/L, and the content of MIL-125(Ti) was 20 %, the composite photocatalyst has the best degradation rate of tetracycline that can reach 92.2 % after 60 min irradiation. In addition, the effects of different mass ratios of MIL-125(Ti)/Bi2O2CO3 composite photocatalysts on the photocatalytic performance were also discussed. Compared with the Bi2O2CO3 monomer, the degradation efficiency of the composites increased gradually with the addition of MIL-125(Ti) from 10 % to 20 %. Through electrochemical characterization, the self-assembly Z-type electron transfer mechanism of MIL-125(Ti)/Bi2O2CO3 composite photocatalyst is expounded, and the problem of overcoming the mismatch of electron and hole mobility is revealed, which solves the wide band gap defect of Bi2O2CO3, according to the first-order kinetic curve, the reaction rate of 20 % MIL-125/Bi2O2CO3 is 4.9 times that of pure Bi2O2CO3.