Energy-Efficient MIL-53(Fe)/Sn3O4 Nanosheet Photocatalysts for Visible-Light Degradation of Toxic Organics in Wastewater

The fabrication of photocatalystswith preferable degradation abilityis critical to purify wastewater. MIL-53-(Fe), as a representativeFe-based metal-organic framework (Fe-MOF), has been widelyused in photocatalysis due to its excellent intrinsic characteristics.However, the inadequate electron number in MIL-53-(Fe) has restrictedthe ability of photodegradation of organic pollutants. Herein, desirable,energy-efficient, and environmentally friendly MIL-53-(Fe)/Sn3O4 nanosheet photocatalysts were first constructed bythe solvothermal method. The characterization results indicated thatthe MIL-53-(Fe)/Sn3O4-5 (5 wt % Sn3O4) catalyst exhibited optimal photoelectric propertiesand maintained a relatively regular morphology. Moreover, the preparedMIL-53-(Fe)/Sn3O4-5 exhibited preferable photodegradationability for dyes and antibiotics under visible light, and the maximumphotodegradation capacity for malachite green, methylene blue, tetracycline,ciprofloxacin, and ofloxacin could reach 96.9, 88.2, 70.3, 83.5, and88.1%, respectively. The initial pH, photocatalyst dosage, and initialconcentration were comprehensively investigated for degrading malachitegreen. In addition, we also explored the prepared catalyst for theremoval of malachite green from different actual wastewater samples.After three cycles, the degradation efficiency of malachite greenby MIL-53-(Fe)/Sn3O4-5 decreased very little,exhibiting good reuse performance. The enhanced photodegradation efficiencyof MIL-53-(Fe)/Sn3O4-5 could be attributed tothe construction of heterojunctions derived from a compact joint interfacebetween Sn3O4 and Fe-MOF, which expedited theseparation ability of photogenerated carriers and broadened the visibleresponse range. The active species trapping experiments and electronspin-resonance results determined that many active species (h(+), center dot OH, and center dot O-2 (-)) were involved in the photocatalytic process. Correspondingly, aconvincible photodegradation mechanism between Sn3O4 and MIL-53-(Fe) was proposed according to the experimentalresults. This study demonstrates that the fabricated Sn3O4 and MOF composites can provide a feasible solutionfor the purification of wastewater.

Automated summary

In this study, desirable, energy-efficient, and environmentally friendly MIL-53-(Fe)/Sn3O4 nanosheet photocatalysts were constructed by the solvothermal method. The catalyst exhibited optimal photoelectric properties, maintained a relatively regular morphology, and showed preferable photodegradation ability for dyes and antibiotics under visible light. The study provides a feasible solution for the purification of wastewater.