Preoaration Of Noble Metals And Carbon Based Functional Nanomaterials And Their Applications In Chemical Sensing And Catalysis

In recent decades,nanoscience has developed very rapidly.The unique physical and chemical properties make nanomaterials widely used in sensing,catalysis,energy storage and conversion,and biomedicine.The properties of nanomaterials mainly depend on the composition and structure of the material.Therefore,assembling materials with different properties into composite materials with a variety of specific functions becomes a research hotspot in the field of nanoscience today.Noble metal-based nanomaterials have excellent chemical stability,biocompatibility,and catalytic activity.Carbon-based nanomaterials have the characteristics of low cost,good conductivity,large specific surface area,and easy surface modification and modification.Focused on noble metals and carbon-based nanomaterials,combining the advantages of macrocyclic moleculars with adjustable cavity size,easy-to-modify chemical groups,strong molecular recognition capability,and good water solubility,this article constructed a series of nanocomposites with excellent sensing and catalytic properties through the covalent and non-covalent interactions between them,to solve technical problems in biosensing,ion detection,pollutant degradation,etc.The main contents include the following parts:（1）Water-soluble pillar[6]arene（WP6）functionalized Pd Pt porous core-shell octahedral nanocrystals（WP6@Pd Pt PCONs）were successfully synthesized by wet chemical method and characterized by TEM,SEM,FT-IR,XRD,XPS and other techniques.The constructed nanocomposite would effectively capture toluidine blue（TB）through the host-guest recognition between WP6 and the probe molecule TB to improve the loading capacity and robustness of TB.In this chapter,an electrochemical immunosensor based on WP6@Pd Pt PCONs nanocomposite was constructed and successfully applied to the detection of neuron-specific enolase（NSE）,a tumor marker of small cell lung cancer.The immunosensor showed excellent analytical capabilities and robustness in the quantitative detection and selectivity test of NSE.（2）Using hydroxyl pillar[5]arene（HP5）as reducing and regulating agent,HP5functionalized gold nanoparticles（Au NPs）,denoted as HP5@Au NPs,were greenly synthesized by one-pot method without heating.With the help ofπ-πstacking,HP5@Au NPs was modified on g-C₃N₄ nanosheets.HP5@Au NPs@g-C₃N₄nanocomposite with good dispersion,large specific surface area and excellent molecular recognition ability was obtained and characterized by TEM,XRD,FT-IR,XPS,BET and other techniques.HP5@Au NPs@g-C₃N₄ would effectively capture the probe molecule methylene blue（MB）through host-guest interaction,which was beneficial to improve the loading capacity and robustness of MB.In this chapter,an electrochemical immunosensor based on HP5@Au NPs@g-C₃N₄ nanocomposite was constructed and successfully applied to the sensing of prostate specific antigen（PSA）,a tumor marker of prostate cancer.The immunosensor showed excellent analytical capabilities in the detection of PSA.（3）The sea urchin-like Au@Pt bimetallic nanocrystals and WP6 were constructed on the surface of nitrogen-deficient carbon nitride（ND-C₃N₄）nanosheets,and WP6@Au Pt@ND-C₃N₄ nanocomposite was prepared and characterized by TEM,FT-IR,XPS,XRD,Raman,EPR and other technical means.The binding constant of the host-guest recognition between WP6 and the probe molecule MB is as high as（1.15±0.30）×10⁷ M^-1,which played an important role in improving the analysis capability of the sensor.The hepatitis B surface antigen（HBs Ag）electrochemical sensor based on WP6@Au Pt@ND-C₃N₄ nanocomposite material showed satisfactory analytical capabilities in stability and sensitivity.（4）Using KMnO₄ and sulfonic calix[8]arene（SCX8）as raw materials,and Au NPs as the nucleation center to grow Mn O₂ nanosheets in situ by wet chemical method,SCX8 functionalized Au@SCX8@Mn O₂ nanoflakes with ultra-thin structure was constructed,denoted as Au@SCX8@Mn O₂.This nanocomposite was characterized by TEM,XRD,Zeta-potential,DLS,FT-IR,XPS and other technical means.The as-prepared Au@SCX8@Mn O₂ was applied to the catalytic reduction of 4-nitrophenol（4-NP）and the catalytic degradation of environmental pollutants MB,and achieved excellent catalytic performances.In addition,using carbon quantum dots（CQDs）as fluorescent probe,a fluorescence sensing platform of CQDs-Au@SCX8@Mn O₂ was constructed and applied to the sensing of glutathione（GSH）,an important component in the human body.In the detection experiment of GSH,the sensing platform showed excellent analytical performances.（5）Nitrogen-doped carbon quantum dots（N-CQDs）with high quantum yield were synthesized by hydrothermal method using citric acid and allylamine hydrochloride as raw materials and characterized by TEM,XPS,XRD,FT-IR and Raman.The prepared N-CQDs were applied to the colorimetric and fluorescence detection of Fe³⁺and showed good analytical performances.In this chapter,the fluorescence quenching mechanism of N-CQDs was studied in detail by means of Stern-Volmer equation,fluorescence lifetime,UV-Vis absorption spectra,fluorescence excitation and emission spectra.Fundamentally,it is mainly attributed to the joint action of coordination interaction and inner filter effect（IFE）.This result makes us have a new understanding of the quenching mechanism between N-CQDs and Fe³⁺.Because of strong luminescent properties and chemical inertness,N-CQDs is also used as a new substitute for fluorescent inks.