Study On Preparation And Enzyme-Like Properties Of Platinum Group Elements-Porous Carbon Nanocomposites

Because native enzymes are predominantly globular proteins（with a few being RNA ribozymes）,they are often expensive to manufacture and produce,unstable to store,and sensitive to physicochemical conditions.Following a systematic study of the structure-function relationship of natural enzymes,it can be hypothesized that a rational assembly of functional atoms or molecules might lead to similar catalytic activities on enzyme substrates.Emerging research has shown that various metal and metal oxide nanoparticles（such as iron oxide,ceria,and gold nanoparticles）,carbon nanomaterials（including carbon nanotubes and graphene oxide）,and various metal-organic frameworks（MOFs）are It mimics the structure or function of natural enzymes and exhibits excellent catalytic activity.Such man-made nanomaterials with enzyme-like activity are called nanozymes.Compared with natural enzymes,these nanozymes have higher catalytic stability,easier modification,and lower fabrication cost in various biomedical applications.The concept of nanozymes has revolutionized our fundamental understanding of biology and chemistry,facilitating its research and applications in biosensing,biology,and medicine.Based on the above research background,we prepared porous carbon nanocomposites loaded with platinum group elements with peroxidase-like activity for the detection of biomass and heavy metal ions.The specific research contents of this paper are as follows:Chapter 1.IntroductionThe main classification and application status of nanozymes are introduced,and the peroxidase-like colorimetric sensor and its application status are mainly introduced.Finally,the research significance and innovation of the work of this paper are introduced.Chapter 2.Preparation of SA-Pd/NPC and its peroxidase-like activityIn this chapter,single-atom palladium-supported nitrogen-doped porous carbon catalysts（SA-Pd/NPC）were prepared by a solvothermal reaction,and their performance as a mimic peroxidase-catalyzed oxidation of TMB was explored.Aniline monomers first self-polymerize on rigid silica sphere templates,and then agglomerate to form nitrogen-doped porous carbon shells（NPCs）.Under certain reaction conditions,divalent palladium salts can generate single-atom Pd by inserting into the nitrogen cavities of NPCs.Characterization by transmission electron microscopy（TEM）and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）showed that the final SA-Pd/NPC composites were cloud-like and uniform in morphology.Due to the etching of the silica nanoparticles,the composite has a large number of mesopores with high stability,and the single palladium atoms are uniformly distributed on the carbon matrix.The catalytic ability of SA-Pd/NPC was tested by TMB-H₂O₂system.Due to the abundant catalytic centers of single-atom Pd,high porosity,large specific surface area,and strong electron transfer ability,the SA-Pd/NPC composite exhibits excellent catalytic ability.The antioxidant levels of two different radical trapping models were sensitively detected by UV-Vis spectroscopy via SA-Pd/NPC-catalyzed TMB-H₂O₂reaction.Chapter 3.Preparation of NP-Pt/NHCS and its peroxidase-like activityIn this chapter,a platinum nanoparticle catalyst（NP-Pt/NHCS）was synthesized by a hard-template method as a peroxidase mimetic to catalyze the oxidation of TMB as a substrate,achieving highly sensitive detection of Cr（VI）.The platinum nanoparticles are encapsulated in silica spheres,and the carbon shell is coated,and then the middle layer of silica is etched to obtain a hollow platinum nanoparticle-containing carbon shell material NP-Pt/NHCS.Due to its unique cage-bell structure,NP-Pt/NHCS exhibits excellent catalytic activity for oxidation.In addition,using 3,3’,5,5’-tetramethylbenzidine（TMB）as a colorimetric sensing probe,and 8-hydroxyquinoline（8-HQ）as an inhibitor of TMB oxidation,the detection of Cr（VI）detection.A specific interaction between Cr（VI）and 8-HQ results in the reversion of ox TMB to blue color.The method showed excellent sensitivity with a detection limit of 2.5 n M and a linear range from 25 n M to 5μM.It also exhibits high selectivity for a range of metal cations.