Precious Metal / Polycaprolactone @ Polypyrrole Composite Nanometer Material And Its Application

Nano materials are referred to those of which one dimension is in the nanometer scale at least in the three-dimensional space or that the materials use as basic units. It can be an excellent catalyst due to its nano scale size, large specific surface characteristics, and highly unsaturated sites as well as the significant increase of surface active sites along with its surface defects. Generally, the nano materials can be categorized into four groups: nanopowder, nanofiber, nanofilm, and nanobulk. In this study, Nano-fiber is of interest because of its wire like material with a diameter of nanoscale and long length and its potential to be used in micro wires, micro fiber materials, novel laser materials, and Light-emitting diodes materials as well as the sensing materials. While in this specific study, Electrospinning has been employed to fabricate the nanofibers due to its relatively simple and effective production method and its capability to prepare the materials with high porosity and high specific surface area.Metal nanomaterials are the great part of nanometer materials with the highly attractive chemical and physical properties. It has been applied to electrochemical sensors to improve its performance of reducing the overpotential, increasing surface active sites and enhancing the selectivity and the sensitivity. The electrochemical sensors based on metal nanomaterials have been becoming a hot topic in the research field. In order to avoid the aggregation during the preparation of nanoparticles of precious metals such as platinum, gold and silver, the metal nanoparticles are typically deposited on the surface of polymer to inhibit the agglomeration.Polypyrrole（PPy） is a major kind of heterocyclic conjugated conducting polymerswith the excellent electrical conductivity electron transportation, and chemical stability as well as the redox-oxidation property. It has been used as a reactive substrate or a functional supporting substrate with high conductive surface area because of its outstanding physical and chemical properties, while at the same time it has been becoming the important research field because of its relatively simple fabrication and various potential applications.According to the above-mentioned characteristics, in this work, we have fabricated the metal（Ag, Au, Pt）-PPy nanocomposites and investigated the catalytic performance of those materials toward the reaction and detection of hydrogen peroxide（H2O2）, uric acid（UA） and methanol（CH₃OH） as well as their practical applications. The research work has been focused in 3 areas:1. A piece of conductive cloth has been successfully constructed with polypyrrole coated silver nanoparticle（Ag@PPy） composites decorated on electrospun polycaprolactone（PCL） nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via photo-induced one-step redox reaction. The resulting Ag@PPy/PCL@PPy composites hold the advantages of improved stability, enhanced dispersion of Ag NPs and the Ag@PPy/PCL@PPy composites can be prepared in the massive way. The composite has been applied for H2O2 detection. The results showed that the obtained electrode has the low detection limit of 1μM and the wide linear detection range from 0.01 mM to 3.5 mM toward the detection of H2O2. The electrode also shows the good stability and selectivity during the detection.2. Gold/polycaprolactone@polypyrrole（Au/PCL@PPy） composite has been prepared by electrospinning and one-step redox reaction and used as the enzyme-free UA sensor. The structures and surface morphologies of Au/PCL@PPy were characterized by field emission scanning electron microscopy（FE-SEM）, transmission electron microscope（TEM）, X-ray diffraction spectrum（XRD） and X-ray photoelectron spectroscopy（XPS）. The electrochemical properties toward to reaction of UA were analyzed by cyclic voltammetry（CV） and differential pulse voltammetry（DPV）. The as-prepared electrode demonstrated its high sensitivity, wide linear range and excellent stability toward the detection of UA which has been attributed to the synergy effect of gold nanoparticles and conductive polymers. In addition, Au/PCL@PPy-based electrode has been proved to detect UA in the presence of AA and can be applied to detect UA in human urine.3. Platinum/polycaprolactone@polypyrrole（Pt/PCL@PPy） composite has been prepared by the electrospinning, one-step redox reaction and the electrochemical deposition technique. The catalytic activity of Pt has been greatly improved using the conductive nanofiber as the catalyst carrier with high surface area and high conductivity. The electrochemical properties of Pt/PCL@PPy toward the oxidation CH₃ OH were evaluated by cyclic voltammetry（CV） and linear sweep voltammetry（LSV）.