Electrocatalytic Electrodes For Methanol Oxidation And Carbon Dioxide Reduction

In the past century, Along with the rapid economic development, the demand forenergy keeps increasing. Generally, human gets energy from the burning of fossilresources （including oil, gas and coal）. However, the fossil resources are of limitedand non-renewable, and the pollution resulting from fossil fuels is caused by the toxicemissions. Meanwhile, the burning of fossil fuels increases the amount of green housegases in atmosphere, especially carbon dioxide. Therefore, the development ofrenewable clean energy and the conversion of CO₂into useful fuel is dedicated toresearch.Nanomaterials with high catalytic activity, large surface area, strong affinity，have been widely used in the field of electrocatalytic materials. Nanomaterialselectrode is of significant nanometer effect and special electrocatalytic activitycompared with a bulk electrode. Several nanomaterials based electrodes have beenprepared and have been researched on the performance of its electrochemicaloxidation of methanol and reduction of CO₂. The main points in this thesis aresummarized as follows:（1） Carbon nanotubes were non-covalently functionalized by poly（diallyldimethylammonium chloride）（PDDA）. We used a strategy to spontaneouslydeposit noble metal NPs on carbon nanotubes. CNTs-PDDA was characterized byFourier transform infrared spectrometry, thermogravimetric analysis and Ramanspectroscopy. The results implied that the surface of CNTs was successfully coatedwith PDDA film by Ï€-Ï€ stacking interaction and the functionalization process had nodetrimental effect on the structure of CNTs. The obtained catalyst （PtNPs/CNTs-PDDA） was characterized by transmission electron microscopy and theresults showed that Pt NPs with an average diameter of ca.2nm were highlydispersed on the surface of CNTs-PDDA. The electro-catalytic properties of PtNPs/CNTs-PDDA nanohybrids towards methanol oxidation were further characterizedby cyclic voltammetry and chronoamperometry. Compared with Pt NPs supported onthe pristine CNTs, the obtained catalyst （Pt NPs/CNTs-PDDA） had a higherelectrochemical surface area, specific mass activity and better stability towardsmethanol electro-oxidation.（2） Pb NPs and Au NPs were supported on CNT， and the obtained Pb NPs/CNTs and Au NPs/CNTs nanohybrids were used as electrocatalysts for theelectrochemical reduction of CO₂. Ionic liquids BMIM-BF₄is selected as a cocatalyst.The micrograph of Pb NPs/CNTs and Au NPs/CNTs nanohybrids and theirelectrocatalytic properties for reduction of CO₂were characterized by transmissionelectron microscopy （TEM） and cyclic voltammetry （CV）, respectively. The resultsshowed that Pb NPs and Au NPs were highly dispersed on the surface of CNTs.Electrocatalytic activity for the reduction of CO₂in aqueous solution of BMIM-BF₄was much better than that of KHCO3. The potential of carbon dioxide reduction PbNPs/CNTs in BMIM-BF₄aqueous solution was420mV more positive than hydrogenevolution potential. Meanwhile, the onset peak potential of CO₂reduction of AuNPs/CNTs in BMIM-BF₄aqueous solution was-0.58V Vs Ag/AgCl.（3） Zeolitic imidazolate framework-8（ZIF-8） nanopolyhedrons was prepared.The morphological of ZIF-8were characterized by scanning electron microscopy（SEM）, and the electrocatalytic properties for reduction of CO₂were characterized bycyclic voltammetry （CV）, and Linear sweep voltammetry（LSV）. The results showedthat: ZIF-8NPs showed dodecahedral structure and uniform shape and showedcapability for the electrochemical reduction of CO₂. ZIF-8supported on Acetyleneblack was prepared to improve performance of electrocatalytic. The electrochemicalimpedance spectroscopy test and chronoamperometry test found that the electrontransfer performance and stability of ZIF-8NPs/C was better than ZIF-8NPs.