Electrocatalytic Performance Of Pd-based Catalyst Synthesized Through Pyrolysis Using Ionic Liquids As Solvent

With the rapid development of modern science and technology, people are increasinglyaware of the importance of environmental protection. Direct ethanol fuel cell because of itshigh rate of energy conversion, green and Pt resources are limited and expensive, so theresearch of a new type of anode catalyst gradually become research focus. In this thesis, thePd and Pd-based catalyst material were prepared by pyrolysis method. The catalysts werecharacterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanningelectron microscopy （SEM） and energy dispersive spectroscopy （EDS）, Electrochemical testswere carried out by cyclic voltammeters （CV）, impedance （EIS） and chronoamperometry （i-t）for the preparation of a variety of catalysts.The main experiment as follows:1.The sample which different molar ratios of Pd and Ni were synthesized by a method ofpyrolysis in room temperature ionic liquid （EMIBF₄）, denoted as Pd_xNi_y/MWCNTs. Pdparticles supported on MWCNTs（multi-walled carbon nanotubes） were tested by the XRDand the results showed that Pd nanoparticles with highly crystalline structure and a diameterof around6nm were prepared. EDS proved the existence of elemental Ni on the surface ofthe MWCNTs. TEM images proved the preparation of Pd_xNi_ynanoparticles, too. Theelectrocatalytic performance of Pd3Ni1/MWCNTs-modified glassy carbon electrode towardsethanol oxidation reaction （EOR） was also probed by CV, demonstrating that it showed thehighest electrocatalytic activity.2.Multi-walled carbon nanotubes （MWCNTs） decorated with PdxCoy（atomic ratios of Pdto Co were3:1,3:1.5,3:2,3:3,respectively） nanoparticles （denoted as PdxCoy/MWCNTs）were fabricated by a simple pyrolysis process, in which room temperature ionic liquids（RTILs） of butyl-3-methylimidazolium hexafluorophosphate （denoted as [BMIM]PF6） wasused as the solvent. X-ray diffraction （XRD）,energy dispersive spectroscopy （EDS） andtransmission electron microscopy （TEM） were all used to characterize the PdxCoy/MWCNTscatalysts, showing that the PdxCoyparticles were uniformly dispersed on the surface of theMWCNTs with an average particle size of²5.0nm. The electro-catalytic activity of the PdxCoy/MWCNTs catalysts toward ethanol oxidation reaction （EOR） was examined by cyclicvoltammetry （CV） and linear sweep voltammetry （LSV）, and the results showed that the onsetpotential of Pd₃Co_1.5/MWCNTs catalyst since peak potential approximately is negative90mVthan Pd₃Co₁/MWCNTs catalyst in an alkaline environment.Therefore, it can be concluded,Pd₃Co_1.5/MWCNTs has the best catalytic activity towards ethanol oxidation reaction （EOR）.The test of CV and EIS further proved this conclusion, too.3.Pd3Au1/MWCNTs, Pd₃Co₁/MWCNTs, Pd/MWCNTs and Pd₃Cu₁/MWCNTs catalystwere synthesized using ionic liquids successfully. The samples were tested by the XRD andEDS, the results showed that the Pd₃Cu₁/MWCNTs had the minimum average particlediameter. The electrocatalytic performance of the sanmle toward ethanol oxidation reaction（EOR） was examined by cyclic voltammetry （CV）, the results showed that Pd₃Cu₁/MWCNTs modified GC electrode have the highest catalytic activity for ethanol, but thestability of the Pd₃Co₁/MWCNTs was higher than Pd₃Cu₁/MWCNTs.4.The large particles of Au was prepared in ionic liquids by a simple pyrolysismethod.The different crystal structures of the samples were prepared by varying the pyrolysistime. The structure and crystal types of the sample were characterized by SEM and XRD. Theelectrocatalytic performance of the sanmle toward oxygen reduction reaction （ORR） wasexamined by cyclic voltammetry （CV） in a solution of0.1M Na₂SO₄, the results showed thatthe catalyst of pyrolysis of three time modified GC electrode has the best catalytic activitytowards oxygen reduction reaction （ORR）.