A bimetallic (Co/2Fe) metal-organic framework with oxidase and peroxidase mimicking activity for colorimetric detection of hydrogen peroxide

A bimetallic metal-organic framework of the type MOF(Co/2Fe), synthesized by a hydrothermal method, is demonstrated to exhibit peroxidase-like activity and oxidase-like activity. The material catalyzes the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) to produce a blue product both in the absence and presence of H2O2. Its catalytic activity strongly depends on temperature and the solution pH value. With its dual enzyme mimetic activity, MOF(Co/2Fe) has the advantages of low cost, good stability, ease of preparation, and attractive Michaelis-Menten behavior. The mechanisms and kinetics of the pseudo-enzymatic activity were studied in some detail. A colorimetric method was developed for determination of H2O2 that is based on the peroxidase-like activity of MOF(Co/2Fe). Under the optimal conditions, the absorbance of oxidized TMB at 652 nm increases linearly in the 10 to 100 μM H2O2 concentration range, with a 5 μM limit of detection.