Platinum Nanoparticle Encapsulated Metal-Organic Frameworks for Colorimetric Measurement and Facile Removal of Mercury(II).

Pt nanoparticle (Pt NP)@UiO-66-NH composites were synthesized and encompassed the benefits of permanent porosity, high thermal and chemical stability of metal-organic frameworks (MOFs), together with the functional behavior of isolated Pt NPs. The PVP-stabilized Pt NPs with the average diameter of 2.48 nm were well dispersed and confined within the framework of UiO-66-NH. Pt NPs possess highly peroxidase-like activities and make the composites oxidize 3,3',5,5'-tetramethylbenzidine in the presence of HO. Moreover, the specific interaction between Hg and Pt NPs leads to the effective suppression of the peroxidase-like activity of Pt NP@UiO-66-NH, which endows excellent selectivity for Hg measurement over the interfering metal ions. Based on the colorimetric sensing system, Hg is linearly measured over the range from 0 to 10 nM with a detection limit of 0.35 nM. Moreover, the as-obtained Pt NP@UiO-66-NH nanocomposites exhibit high capacity and good selectivity for Hg adsorption, which is successfully applied to treat Hg in water with removal efficiency over 99%. With these findings, Pt NP@UiO-66-NH composites can be used to develop a simple and rapid colorimetric sensing system and are utilized as nanoadsorbents for facile removal of Hg. This work not only expands the scientific researches on MOFs but also provides practical application in environmental, biological, and relative fields.