Preparation Of MOFs Derived Composites And Its Biomimetic Catalytic Performance

This study concentrated on the synthesis of these derivative composite materials from iron-based metal-organic frameworks Fe(Ⅲ)-MOFs and the catalytic properties of their mimetic peroxidase.Natural peroxidase is a kind of widespread enzyme protein in biological systems. Due to their high efficiency and substrate specificity under very mild and environmentallyfriendly conditions, they have significant practical applicationsin medicine, biotechnology and environmental analysis. However, natural enzymes bear some considerable disadvantages, such as a relatively low stability, a sensitivity of catalytic activity in environmental conditions, difficulty in storage and purification. Thus, nanomaterials peroxidase mimetics gradually develop a hotspot in the field of materials research. Metal-organic frameworks (MOFs) are a relatively new class of porous inorganic-organic materials with fascinating structures and intriguing properties, such as high specific surface area, uniform structured nanoscale cavities, and wide variety of shapes and porosity. Therefore, MOFs become ideal material of building biomimetic systems.In this paper, we prepared four kinds of Fe(Ⅲ)-MOFs materials MIL-n (n=101, 53,100,88A) and MOFs derivative composites. The composite materials, including magnetic mesoporous carbon (FeOx-C), iron oxides (Fe2O3), hematite iron oxides-MOFs composites (α-Fe2O3@MOFs) and Fe3O4 magnetic particles, were formed by controlling the calcining condition during thermolysis of Fe(Ⅲ)-MOFs. The peroxidase-like activity of these MOFs and their derivative composites was evaluated by the catalytical oxidation of typical peroxidase substrates 3,3’,5,5’-tetramethylbenzidine (TMB) and o-phenylendiamine (OPD) by H2O2. It was found that the as-prepared MOFs derivative composite materials exhibit intrinsic peroxidase-like activity.Based on the systematic research, MIL-100 derivative composites (α-Fe2O3@MIL-100, Fe3O4) were found to show much higher peroxidase-like catalytic activity. The effect of various factors on the catalytic activity of peroxide mimic enzymes were studied. The results showed that the best pH value is 5.0 and the best temperature is 40℃. The catalytic kinetics of the as-prepared MIL-100 and its derivative composites was carried out, and the Michaelis constant values with H2O2 and TMB as the substrates were obtained.Kinetic analysis indicated that the catalytic behavior was consistent with typical Michaelis-Menten kinetics.The Km values of the as-prepared α-Fe2O3@MIL-100 with H2O2 and TMB as the substrates was lower than those of MIL-100 and Fe3O4. This implies that the as-prepared α-Fe2O3@MIL-100 has higher affinity for H2O2 and TMB than MIL-100 and Fe3O4.MIL-100(Fe) and its derivative composites composites (a-Fe2O3@MIL-100, Fe3O4) were successfully used for the catalytic removal of methylene blue with H2O2. With 0.05 mg/mL catalysts and 80℃,α-Fe2O3@MIL-100 could catalytic degradation of methylene blue (MB) in 14 min.It will have great potential applications in the environment protection.