Photocatalytic degradation of persistent antibiotic pollutants by MOF-derived bird-nest ferric molybdate

Abstract

A photocatalyst (PC) with an optimized morphology exhibits better pollutant photodegradation because of the augmentation of the surface area available for redox reactions and light harvesting. Here, we synthesized a Fe2(MoO4)3 (FMO) PC from a coordinated Fe metal-organic framework (MOF) precursor. During this process, FMOMOF was pyrolyzed to rearrange the organic structure of the Fe-MOF precursor. This synthesis strategy resulted in a unique PC made of stacked nanosheets (NSs) organized in a bird-nest structure. Compared to smooth FMOFC spheres synthesized from uncoordinated Fe ions, FMOMOF exhibited a 3.6-time larger surface. In addition, FMOMOF NSs were accompanied by smaller nanoparticle and quantum dot satellites, which expedited charge separation. FMOMOF was evaluated for the photodegradation of the polluting antibiotics tetracycline hydrochloride (TCH) and oxytetracycline hydrochloride (OTCH). The PC readily photodegraded above 90 % of both antibiotics and completely mineralized a large fraction. Illuminated FMOMOF oxidized TCH and OTCH 1.6 to 3.0 times faster than FMOFC and was also reusable. A larger surface exposing more redox sites and a better charge separation efficiency were responsible for the improved photooxidation performance of FMOMOF. Thus, these results describe how a MOF precursor can be employed to develop a promising FMO PC capable of removing recalcitrant antibiotics.