Metal-organic framework helps photocatalyst to breakdown antibiotics in nature

Antibiotics, although an indispensable invention of modern medicine, can bioaccumulate in the natural environment and pose risks to human and ecosystem health. One such antibiotic, tetracycline, had been detected in natural water sources, such as in rivers and underground water. Researchers have explored strategies to remove tetracycline from water, including using biodegradation and physical adsorption, but have yet to find an effective method.

Photocatalytic oxidation could provide a solution – with the right photocatalyst. For this purpose, Li et al. developed a photocatalyst that uses sunlight to degrade tetracycline.

Although the semiconductor bismuth oxybromide (BiOBr) can be an efficient photocatalyst due to its bandgap, chemical stability, and simple synthesis, it contains defects that hinder its photocatalytic ability. To help BiOBr overcome these defects, the authors synthesized BiOBr/UiO-66 nanocomposites based on UiO-66, a metal-organic framework.

UiO-66 is not a great photocatalyst itself, but its metal-organic framework helps enhance the photocatalytic performance of BiOBr. The nanocomposites demonstrated a high degradation efficiency and mineralization ability under visible light, with a maximum degradation activity about 2.15 times higher than pure BiOBr. The hydrothermal method used to synthesize the nanocomposites also enhanced the interaction between BiOBr and UiO-66.

“Our work combined two useful materials to construct a BiOBr/UiO-66 composite with an improved photocatalytic performance by optimizing both the active facet ratio and energy band structure,” said author Yonghu Han.

The authors determined that the byproducts of using BiOBr/UiO-66 nanocomposites to degrade tetracycline were carbon dioxide and water, plus some other minor degradation products, suggesting that this photocatalysis avoids secondary pollution.

Next, the authors plan to extend this technique for the removal of other environmental pollutants.

Source: “Zr-MOFs based BiOBr/UiO-66 nanoplates with enhanced photocatalytic activity for tetracycline degradation under visible light irradiation,” by Xianyang Li, Deqi Zhang, Rongbiao Bai, Ruixue Mo, Chengwei Yang, Caolong Li, and Yonghu Han, AIP Advances (2020). The article can be accessed at https://doi.org/10.1063/5.0030228 .