Fabrication of new MIL-53(Fe)@TiO2 visible-light responsive adsorptive photocatalysts for efficient elimination of tetracycline

Novel semiconductor-MOFs composites based on TiO2 and MIL-53(Fe) were constructed using a facile one-pot solvothermal process and acted as effective visible-light responsive adsorptive photocatalysts for the removal of tetracycline (TC). The resultant MIL-53(Fe)@TiO2 composites were characterized by comprehensive analyses, ESR, and photoelectrochemical measurements. Experimental results showed that the synthesized MIL-53(Fe) @TiO2 composites possessed enhanced adsorption and excellent photocatalytic activity for TC solution under visible light irradiation. Among all the composites, the MIL-53(Fe)@TiO2 = 1:2 exhibited optimal removal performance compared with pristine MIL-53(Fe) and TiO2. The results of UV-vis DRS verified the visible light absorption range of the prepared composite was improved, and the results of the Nyquist plot illustrated that the transfer ability of photo-generated charge carriers was boosted. More importantly, the ESR results showed that the center dot O-2(-) and center dot OH active species played a crucial role in photocatalytic reactions. The enhanced photocatalytic ability was due to not only the fabrication of the n-n type heterojunction photocatalysts, which could provide more active species, but also the synergy between MIL-53(Fe) and TiO2 in the composites. A possible reaction mechanism was proposed to elucidate the reason for the photocatalytic performance enhancement. Our findings may open up a new field for Fe-MOF and semiconductor composite materials in removing TC in visible light.

Automated summary

The novel semiconductor-MOF composites based on TiO2 and MIL-53(Fe) showed enhanced adsorption and photocatalytic activity for tetracycline under visible light, with the 1:2 ratio of MIL-53(Fe)@TiO2 demonstrating optimal performance. The improved performance was attributed to the n-n type heterojunction photocatalysts and synergy between MIL-53(Fe) and TiO2 in the composites, leading to enhanced visible light absorption and boosted charge carrier transfer ability.