Preparation Of New Transition Metal/Carbon Nanocomposites And Their Application In Analytical Chemistry

In this paper, we studied the electrochemical behavior of several biological molecules on the transition metal/graphene-carbon nanotubes(Gr-CNTs) nanocomposites modified electrodes. The transition metal/Gr-CNTs nanocomposites were synthesized through liquid phase reduction method, several noble metal nanocomposites were successfully synthesized and their morphology and crystalline structures were characterized and analyzed carefully. Additionally, transition metal/Gr-CNTs nanocomposites-based nanocomposites modified electrodes were prepared and applications in electrochemical analysis were also extensively studied. The main contents are as follows:1. The sandwich lamination structure of Gr-CNTs nanocomposite has been fabricated through in situ facile and green method. Then Pt nanoparticles are fabricated on Gr-CNTs via a simple one-step chemical reduction method in ethylene glycol (EG) and water system. The Pt/Gr-CNTs was further characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), which indicated that the as-synthesized Pt nanoparticles was successfully dispersed on the surface of Gr-CNTs nanocomposite. Electrochemical study has been proved that the Pt/Gr-CNTs nanocomposite has higher catalytic activity in neutral medium for methanol oxidation, which is hopefully used in variety types of cells and biosensors in physiological medium.2. Pt/Gr-CNTs nanocomposite based electrochemical sensors for the determination of endocrine disrupter bisphenol A in thermal printing papers. A facile and green method was developed to synthesize the Gr-CNTs nanocomposite with a sandwich lamination structure. Pt nanoparticles were loaded on the assynthesized Gr-CNTs nanocomposite to prepare an electrochemical sensor for determining bisphenol A (BPA) in thermal printing paper. The electrochemical behavior of BPA on the Pt/Gr-CNTs nanocomposite was investigated by cyclic voltammetry (CV) and chronocoulometry (CC). The direct determination of BPA was accomplished by using differential pulse voltammetry (DPV) under optimized conditions. The oxidation peak current was proportional to the BPA concentration in the range from6.0*10"8to 8.0x10-5M. The detection limit was4.2×10-8M (S/N=3). The fabricated electrode showed good reproducibility, stability and selectivity. The proposed method was successfully applied to determine BPA in thermal printing papers samples and the results were satisfact.3. Anew facile in situ direct synthesis method of graphene-aniline (Gr-aniline) nanocomplex by a chargetransfer self-assembly technology at organic-aqueous interface was developed in this work. The graphene-polyaniline (Gr-PANI) nanocomposite was prepared by simultaneous electropolymerization of Gr-aniline, and palladium nanoparticles were loaded onto the Gr-PANI nanocomposite to be used as a new electrode material for electrochemical sensing. Hydroquinone (HQ) and catechol (CC) were used as probe molecule to evaluate the electrocatalytic activity of Pd/Gr-PANI nanocomposite. The Pd/Gr-PANI nanocomposite shows so excellent electro-catalytic activities toward the oxidation of HQ and CC isomers that the oxidation peaks of the two molecules were well and easily resolved. The excellent reproducibility, stability and selectivity of the Pd/Gr-PANI nanocomposite make it a potential candidate as electrochemical sensor for simultaneous determination of HQ and CC isomers.4. Silver nanoparticles modified graphene-carbon nanotubes/polyimide (Gr-CNTs/PI) films have been prepared by electrochemical reduction of silver nitrate on potassium hydroxide hydroxylated of Gr-CNTs/PI films surface. The as-prepared nanocomposites were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), X-ray diffraction(XRD) analyzer and semiconductor characterization system. The lower content of Gr-CNTs (10wt.%) doping in PI matrix can improve the conductivity of PI films more clearly than pure CNTs. The conductivity can be regulated by controlling Gr-CNTs content in PI matrix. These silver nanoparticles into Gr-CNTs/PI films presented here can act as deposition seeds which can initiate subsequent electroless silver or copper or electrodeposition other metal.5. In this work, a simple MoS2/PDDA-MC modified glassy carbon electrode (GCE) sensor has been fabricated. The electrochemical behavior of L-Cys was investigated on MoS2/PDDA-MC modified GCE.