Study On The Catalytic Performance Of Nanoenzyme Based On Metal Sulfide FeS₂ Composite Materials

Nanoenzymes,nanomaterials with intrinsic enzyme-like properties,have boomed in the past decade due to their ability to address the limitations of natural enzymes such as low stability,high cost,and difficulty in storage.With the rapid development and deepening understanding of nanoscience and nanotechnology,nano-enzymes are expected to serve as direct substitutes for traditional enzymes by simulating and further designing the active centers of natural enzymes.Among many nanomaterials,ferric sulfide（FeS₂）exhibits intrinsic peroxide-like activity,but its inherent defects limit the catalytic activity.Therefore,how to further improve the catalytic activity of these nanomases has become a research hotspot.Composite materials not only maintain the advantages of the material properties of each component,but also through the complementary and correlation of the properties of each component can obtain the comprehensive properties that can not be achieved by a single component material.Iron-based sulfide composites usually exhibit high surface area,rapid electron transport capacity and superior enzyme-like activity.In this paper,hollow spherical SiO₂ as composite material,using a simple onestep solvothermal method to prepare hollow spherical FeS₂/SiO₂,SiO₂ carbonized into hollow C spheres,synthesis of S-doped FeS₂/SC,and on the basis of the incorporation of transition metal Ni,to obtain a better enzyme activity,substrate affinity more excellent nanase.The related characterization and the mechanism of enzyme activity were studied.The main contents of this paper are:1.FeS₂/SiO₂ was synthesized by one step solvothermal method.FeS₂ grows uniformly on the surface of hollow spherical SiO₂,the specific surface area increases by about 8.5 times,and the Zeta potential becomes more negative.By colorimetric method,the detection of ascorbic acid（AA）has a lower detection limit（0.026 μM,S/N=3）,and the detection time is short（1 min）.The detection system has excellent repeatability and anti-interference.It can show good detection ability in real samples.2.The hollow spherical SiO₂ was carbonized into hollow carbon spheres,and then S-doped FeS₂/SC was prepared by one-step solvothermal method.The catalyst retained a large specific surface area（36.94 m²/g）,and the surface defects of graphite carbon caused by S atom doping during the synthesis process increased the surface electron transport rate,thus improving the peroxidase activity.Compared with FeS₂/SiO₂,the Km value of H₂O₂ and TMB decreases,and the catalytic efficiency（Kcat/Km）increases.A colorimetric assay system for the detection of cysteine（Cys）was established.The detection range was wide（20-120 μM）and the detection limit was 0.061 μM（S/N=3）.The system could quickly and sensitively detect Cys in real samples within 1 min at room temperature.3.On the basis of the previous chapter,FexNi1-xS2/SC was synthesized by one-step solvothermal method with transition metal Ni.The incorporation of Ni metal improves the specific surface area（67.33 m²/g）,the defect sites on the carbon surface increase,and ≡Ni²⁺accelerates the conversion rate of ≡Fe³⁺ to ≡Fe²⁺,and the enzyme-like activity is improved.With the incorporation of Ni element,the affinity with substrate was enhanced and the catalytic efficiency increased.The range of Cys detected by colorimetric method increased（1.0-180 μM）,and the detection limit decreased（0.049μM,S/N=3）.