The Preparation And Application Of Polyimide/Graphene Electrode

In this thesis, a polyimide/reduced graphene oxide (PI/rGO) composite was prepared by means of in situ polymerization. The prepared PI/rGO composite film has excellent conductivity, corrosion resistant, strong acid and alkali resistant and high or low temperature resistant. Semiconductor materials were prepared on this PI/rGO electrode by various electrochemical techniques. The modified electrode was characterized by means of cyclic voltammeter (CV), Open circuit potential-t (OCP-t), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and so on. Main contents of this thesis include,1. Preparation of SnSe on conductive polyimide electrode by electrochemical atomic layer deposition method and the study on enhanced electrochemical performance. Because of polyimide (PI) is an insulation film, a conductive polyimide electrode is prepared by incorporating PI with chemical reduced graphene oxide (rGO) which has excellent conductivity. With aim to further optimize surface properties, the surface of PI/rGO electrode is modified with a layer of electrochemical-reduced graphene oxide (EGO). Compared with bare PI/rGO film, the hybrid EGO-PI/rGO electrode own larger active area and better conductivity, which offers the electrode more extensive field to prepare compound and more sensitive surface to detect electrochemical signal. SnSe is prepared on both PI/rGO and EGO-PI/rGO electrode by electrochemical atomic layer deposition (EC-ALD) technology. The semiconductor appears more excellent photoelectric property on EGO-PI/rGO electrode. Moreover, open-circuit potential (OCP) and Mott-Schottky measurement indicated the obtained SnSe is a p-type semiconductor.2. Preparation of Cu-Te compound on Pt particles decorated EGO-PI/rGO electrode via a layer-by-layer electro-deposition method. A Pt nanoparticles decorated conductive polyimide film (Pt/EGO-PI/rGO) was successful prepared and employed as working electrode in this work. The modified Pt particles play a key role in preparing Cu-Te compound array. The density of Cu-Te compound array could be adjusted by controlling the density of modified Pt particles on EGO-PI/rGO electrode. Detailed deposition process was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Photoelectricity characterization and XRD pattern demonstrat the as-prepared Cu-Te compound is a p-type semiconductor with structure. SEM images demonstrated Cu-Te compound was selected grown on Pt particles.3. The study on growth mechanism of dendritic Te on PI/rGO electrode and its application in detection of Pb(Ⅱ) by UPD-ASV technique. Two kinds of dendritic Te crystals were prepared by electrodepositing TeO2 in acidic and alkaline solutions respectively. The nucleation of Te in acidic solution was conformed to progressive type while in alkaline solution was conformed to instantaneous type. By combine with the evolution of morphologies, a growth mechanism for dendritic crystal was proposed. Pb(II) has obvious underpotential deposition phenomenon on Te crystal, therefore, on Te/PI/rGO electrode the deposited Pb could be stripped at a more positive potential. The stripping peak currents varies linearly with the concentration of Pb(Ⅱ) in range of 1.0-55×10-7 mol·L-1 (R=0.9996), with a detection limit of 3×10-8 mol·L-1 (S/N=3).4. A sensitive hydrogen peroxide sensor based on monolayer Ag covered dendritic Te. A monolayer Ag covered dendritic Te (monoAg-Te) was prepared by replacing the monolayer Pb covered dendritic Te (monoPb-Te) with Ag, and the monoPb-Te was prepared by depositing Pb(II) on dendritic Te/PI/rGO under its UPD potential. SEM results demonstrated Ag particles were uniformly dispersed on the surface of Te crystal, and EDS result demonstrated there was no Pb remained on Te crystal. Cyclic voltammetry results demonstrated that the monoAg-Te/PI/rGO electrode exhibited excellent electrocatalytic activity to the reduction of H2O2. The fabricated amperometric hydrazine sensor exhibits high sensitivity of 2580.76μA mM-1·cm-2 and a detection limit of 1.7×10-6 mol·L-1 (S/N=3) with linear range of 5.0-1200×10-6 mol·L-1. In addition, the monoAg-Te/PI/rGO showed good selectivity for H2O2 detection in the presence of several interfering species.5. Electrodeposition of MoTe2 on PI/rGO electrode and its application in detection of hydrazine. MoTe2 was prepared by a pulse electrodeposition method. By adjusting deposition potential and time, three Mo-Te compounds with different stoichiometries were obtained. Cyclic voltammetry was used to evaluate the catalysis of three stoichiometries Mo-Te compound towards hydrazine respectively. Compared to Te/PI/rGO, Mo/PI/rGO, MoTe36/PI/rGO and MoTe0.85/PI/rGO electrode, the MoTe2/PI/rGO electrode displays the best electrocatalytic activity. Amperometric response results indicated that the modified electrode displayed a fast response of less 5s with linear range of 5～3700×10-7 mol·L-1, and a detection limit of 1.7×10-7 mol·L-1 (S/N=3).