Kai Wang,Yi Yang,Tian C. Zhang,Ying Liang,Qingguo Wang
Magnetic Co-doped Fe3O4@FeOOH nanocomposites were prepared in one step using the hydrothermal synthesis process for catalyzing peroxymonosulfate (PMS) to degrade refractory methylene blue (MB) at a wide pH range (3.0–10.0). The catalysts' physiochemical properties were characterized by different equipment; Fe3+/Fe2+ and Co3+/Co2+ were confirmed to coexist in the nanocomposite by X-ray photoelectron spectroscopy. The nanocomposite effectively catalyzed PMS's decoloration (99.2%) and mineralization (64.7%) of MB. The formation of Co/Fe–OH complexes at the surface of nanoparticles was proposed to facilitate heterogeneous PMS activation. Compared with the observation for Fe3O4@FeOOH, the pseudo-first-order reaction constant was enhanced by 36 times due to Co substitution (0.1620 min−1 vs. 0.0045 min−1), which was assigned to the redox recycle of Fe3+/Fe2+ and Co3+/Co2+ in Co-doped Fe3O4@FeOOH. Besides, the catalyst could be easily reused by magnetic separation and exhibited relatively long-term stability.
The convenience of colorimetric sensors is useful for practical applications. In this work, we constructed a novel colorimetric sensor with magnetic separation ability that can be operated in nearly neutral conditions and achieve one-step detection of metabolites. Magnetic Cu doped Fe 3 O 4 @FeOOH magnetic nanocomposite (Cu/Fe 3 O 4 @FeOOH) with an oxygen vacancy was prepared by a one-step self-assembly hydrothermal method, and fully characterized by different methods. The oxygen vacancy generated by the incorporation of Cu 2+ cations into the Fe 3 O 4 @FeOOH structure was confirmed to be a vital reactive site for enhancing the catalytic activity, which opens up a new way of designing highly efficient enzyme mimics. Benefiting from its inherent horseradish-peroxidase-like activity, a simple and selective enzyme-based colorimetric sensor was developed for one-step detection of H 2 O 2 and cholesterol, and 3,3′,5,5′-tetramethylbenzidine was catalyzed by H 2 O 2 to generate a colored product of oxidized 3,3′,5,5′-tetramethylbenzidine for signaling. H 2 O 2 and cholesterol can be linearly detected in the same range from 0.01 to 0.4 mmol L -1 with detection limits of 0.0075 mmol L -1 and 0.0082 mmol L -1 , respectively. The proposed colorimetric sensor has satisfactory reusability, accuracy, and practicability in human serum samples, indicating its potential application for the detection of different metabolites in the fields of life science and analytical science.
Graphical abstract
危险品化学品经营许可证（带存储）