Preparation And Application Of Graphene, Carbon Nanotubes/Polyimide Modified Electrodes

In this thesis, reduced graphene oxide/ polyimide?rGO/PI? and multiwalled carbon nanotubes/polyimide?MWCNTs/PI? composite membrane electrodes were prepared by means of in situ polymerization. The prepared PI-based composite electrodes have advantages of excellent electrical conductivity, good stability and repeatability, low cost, easy operation, green and pollution-free. Sequences of modified electrode materials were prepared on the PI-based electrodes via electrochemical techniques. Modified electrode materials were prepared by methods of current^time?i^t?, underpotential deposition?UPD?, pulse electrodeposition method?PED? and cyclic voltammeter?CV?. The morphologies, structures and characteristics of the modified electrode materials were studied by scanning electron microscope?SEM??JSM-6701 F Japan?, X-ray photoelectron spectroscopy?XPS?, X-ray diffraction?XRD?, open circuit potential^time?OCP^t? and so on. Main contents of the thesis are described as follows:2. Preparation of Pt@Te-rGO/PI modified electrode and its application in hydrogen evolution. A promising Pt@Te nanoparticles catalyst has been synthesized on the surface of the rGO/PI substrate. First of all, Te was deposited on the rGO/PI using electrochemical deposition method to obtain Te-rGO/PI that has various morphologies. Secondly, a monolayer Pb film was deposited on the Te-rGO/PI by the similar electrochemical method to get a transition state material of Pb@Te-rGO/PI. Finally, the target Pt@Te catalyst on the rGO/PI with large surface area was obtained by a chemical oxidation method. Then the prepared Pt@Te-rGO/PI was used as a working electrode to study the hydrogen evolution behavior in 0.5 mol/L H₂SO₄. By comparison the catalyst of sole Pt-rGO/PI nanoparticles, Pt@Te-rGO/PI catalyst considerably abated the demanding of Pt. And it shows excellent HER activities with a low overpotential of 0.1 V. The Tafel slope of 55 mV dec-1 reveals most likely the Volmer-Heyrovsky mechanism for hydrogen evolution reaction?HER?. On the other hand, the catalyst displays satisfactory stability.2. Pulsed electrodeposition of Cd-MoTe₂-MWCNTs/PI modified electrode and its photoelectrical properties. Nanosemiconductor Cd doped MoTe₂ thin films were prepared on self-made MWCNTs/PI membrane electrode by a PED method that consists ofrepeated cycles of three potential application steps. The Cd, Mo, Te electrochemical system and the related single component electrolytes were studied by CV to identify the electrode processes and study the deposition processes. By adjusting deposition potential and time, four kinds of Cd, Mo, Te compounds with different stoichiometries were obtained. The OCP-t characterization study showed that the Cd doped MoTe₂ thin films exhibited good p-type properties and four kinds of photoelectrical phenomena were observed. The obtained results indicate that the Cd doped MoTe₂ thin films depositing on MWCNTs/PI membrane is appropriate to serve as the solar energy transfer material. This simplified preparation using pulse electrodeposition gives superior quality Cd doped MoTe₂ thin films which are promising for application in thin-film solar cells and photoelectrochemical cells.3. Preparation of CoO_x-rGO/PI modified electrode and its sensitive detection for nitrite. An electrochemical sensor based CoO_x-rGO/PI?Cobalt oxide decorated reduced graphene oxide/ polyimide? modified electrode material was prepared via a simple and environment friendly method of dynamic potential deposition. Through this method, stable and well-distributed CoO_x nanoparticles were formed. The nanomaterials were characterized by XRD, SEM and XPS. CV method was adopted to investigate the electrochemical behaviors of nitrite ion?NO₂^-? on CoO_x-rGO/PI modified electrode preparatorily. The i^t curve indicated that the incorporation of CoO_x-rGO/PI modified electrode had a good catalytic activity for the oxidation of NO₂^-. And this electrochemical sensor showed a good linear relationship in the range of 20 ?M ¹.55 mM, with a low limit of 0.03?m?S/N = 3?. What's more, the sensor exhibited satisfactory anti-interference performance, repeatability and stability.