Synthesis of Os@ZIF-8 nanocomposites with enhanced peroxidase-like activity for detection of Hg²

Metal organic framework (MOF)-derived nanostructures display remarkable characteristics and have broad application potential. Os@ZIF-8 nanocomposites were prepared by a depositional method. The Os nanoparticles distributed on the surface of ZIF-8. The nanocomposites displayed enhanced peroxidase-like activity with smaller K_m for both 3,3',5,5'-tetramethylbenzidine (TMB) and H₂O₂ compared to Os NPs due to the confinement effect and large surface area that ZIF-8 provided. From the average reaction rate constants obtained from three different temperatures, the activation energy values were determined. The kinetic data indicated that the Os@ZIF-8 NCs are catalytically more active than Os NPs. In addition, quantitative measurement of Hg²⁺ was performed based on the formation of Os-Hg alloy. Os@ZIF-8 NCs had a wide detection range between 0 μM and 71.43 μM for Hg²⁺ with a limit of detection (LOD) of 2.29 μM. Using a MOF with a large surface area to load Os nanoparticles to achieve enhanced nanozyme activity is the novelty of this work.