Photo-Fenton composite catalyst CuBi2O4@MIL-53(Fe) for efficient organic pollutant removal in light and dark conditions

The construction of heterojunction photo-Fenton catalysts to activate hydrogen peroxide for the efficient degradation of organic pollutants in water has attracted considerable attention. Herein, a CuBi 2 O 4 @MIL-53(Fe) Z-scheme heterojunction catalyst was successfully prepared by solvothermal method for tetracycline (TC) degradation. In this catalytic system, the heterogeneous photocatalytic reaction and the Fenton reaction form a strong synergistic effect in the degradation of organic pollutants through the transfer of photogenerated electrons. The results indicate that in the presence of trace concentrations of H 2 O 2 (2.60 mM), 0.20 g/L of MC-15 (with CuBi 2 O 4 accounting for 15 % of the mass of MIL-53(Fe)) exhibited the highest catalytic activity, with a TC (150 mg/L) removal rate of 94.0 % after 50 min of visible light irradiation. Interestingly, the MC-15 catalyst can still achieve a removal rate of 62.1 % of TC even under dark conditions. Furthermore, in degradation experiments, MC-15 exhibited high environmental stability and applicability in different natural water system. The excellent catalytic performance of the light/MC-15/H 2 O 2 system is attributed to the quick separation of photogenerated electron-hole pairs from Z-scheme heterojunction CuBi 2 O 4 @MIL-53(Fe) and the accelerated bimetallic ions cycle. A possible photo-Fenton catalytic mechanism of MC-15 catalyst is proposed based photoelectrochemical tests, free radical capture experiment and electron paramagnetic resonance (EPR) analysis. This study provides a reference for the development of iron-based metal-organic framework composite photo-Fenton catalysts.