研究生英语文献汇报PPT.ppt

1,Paper Review,李俊乾 化学工程（专）14102932,Synthesis of bimetallic Pt/Pd nano-tubes and their enhanced catalytic activity in methanol electro-oxidation（双金属铂/钯纳米管的合成和其在甲醇电氧化增强的催化活性）,2,Literature source,3,Contents,Introduction,1,2,Experimental section,1,Conclusions,2,3,4,Results and discussion,4,1.Introduction,The shortage of traditional energy resources and serious environmentalpollution due to combustion emissions have resulted in a number of scientific studies on the development of sustainable and clean energy,including fuel cells.,5,1.Introduction,Methanol oxidation in a direct methanol fuel cell(DMFC)can generate electrochemical energy.,DMFCS working principle:,Anode：CH3OH+H2O CO2+6H+6e-0=0.046V Cathode：3/2 O2+6H+6e-3H2O 0=1.229V,CH3OH+3/2 O2 CO2+2H2O,E0=1.183V,This oxidation usually needs a catalyst to lower the reaction barrier to make the process efficient.So far,platinum(Pt)is the most efficient catalyst in the field.Scarcity of Pt,which causes its high cost,inevitably impedes the active development of both scientific research and practical utilization.The utilization of single-component Pt in DMFCs suffers from serious carbon monoxide(CO)poisoning.CO,one of the main intermediate molecules,can easily stain Pt atoms,which deteriorates their catalytic activity.,6,The article thought：,In this study,we achieved higher catalytic activity for methanol oxidation using the perpendicular bimetallic Pt/Pd NT array as a catalyst.The investigation of the catalytic properties of bimetallic materials paves a way to substituting expensive Pt with cost-competitive materials in the future.,7,Experimental section,2,8,2.Experimental section,5 mM PdCl2,5 mM H2PtCl6,40 mM HCl,used for deposition,The lengths of the NTs can be controlled by using 0.3 to 2 C.,AAO,a vertically-aligned bimetallic Pt/Pd nanotube array,Scheme 1 Schematic drawing of the ion distribution in a porous alumina nano-template.Dashed lines show the electrical double layer of the classical GouyChapmanSterns model between(b)diffusion layer and(c)bulk layer regions in a nanochannel.Region(a)depicts a compact layer.,9,2,3,Results and discussion,10,3.Results and discussion,The average outer diameter and wall thickness of the Pt/Pd NTs were measured as 217(39 nm)and 37(12 nm),respectively.As shown in the SEM images,the resulting morphology of the nanostructures was quite homogeneous over a large area of the sample.,Synthesis of bimetallic Pt/Pd nano-tubes and morphology analysis,11,3.Results and discussion,As the Pt/Pd ratio increased(i.e.,the proportion of Pt4+increased),the nanostructures became rod shapes.,As the Pt/Pd ratio decreased(i.e.,the concentration ofPd2+increased),the nanostructures gradually started to show an open nano-tubular(ONT)shape.,12,3.Results and discussion,When 5 mM Pd and 5 mM Pt precursor ions were in the plating solution,Pt49/Pd51 NTs could be prepared,A plot of atomic%of Pt in Pt/Pd bimetallic nanostructures vs.amount of Pt source,13,3.Results and discussion,(A)TEM image of Pt/Pd NTs with 1 C(2.4 0.4 mm)shows the totally tubular structure from bottom to top.(B)TEM image of a Pt/Pd NT and line-scanning profiles in the radial direction,indicating Pt(red trace)and Pd(green trace)distributions.The corresponding elemental mapping images are shown for(C)Pt and(D)Pd.,14,3.Results and discussion,FE-SEM images(BSE mode)of the Pt/Pd NTs.The lengths of the Pt49/Pd51 NTs were tuned by using(A)0.3 C,(B)1 C and(C)2 C.(D)The Pt/Pd NTs have average lengths from 1.1 0.1 mm to 4.9 0.9 mm.,15,3.Results and discussion,返回,Electro-catalytic properties,(A)Cyclic voltammograms(CVs)of Pt and/or Pd nanostructures withsame lengths(ca.2.4 mm)in 0.5 M H2SO4 solution at room temperature.,As shown in Fig.A,the value of the surface charge of the Pt/Pd NT catalysts was found to be 1.7 times larger than that of the Pt/Pd NRs.,16,3.Results and discussion,(B)Anodic striping of CO oxidation in 0.5M H2SO4 aqueous solution for different catalysts(only the oxidative CO removal region is shown).,The observed peak intensity of CO oxidation on the Pt/Pd NRs was two times higher than that of the pure Pt and Pd NRs.Interestingly,the onset potential of CO oxidation for the Pt/Pd bimetallic nanostructures(0.61 V)appeared at a lower potential compared tothe pure Pt NRs(0.69 V)and the pure Pd NRs(0.79 V).,17,3.Results and discussion,(C)Cyclic voltammograms of methanol oxidation using different catalysts.The inset image shows the magnified onset potential region of the CVs.,The Jf/Jb ratios of the Pt/Pd NTs and Pt NRs were determined to be 1.6 and 1.2,respectively.,The Vonset was found to be in the order:Pt/Pd NTs(0.42 V)Pt/Pd NRs(0.44 V)Pt NRs(0.49 V),18,3.Results and discussion,(D)Comparison of chronoamperograms of methanol oxidation for different catalysts at 0.4 V(vs.Ag/AgCl).Electrolyte for methanol oxidation:0.5 M H2SO4 and 0.2 M CH3OH solution at room temperature.Scan rate:50 mV s-1.,We found that Pt/Pd NTs showed the highest current density compared to other nanostructures.,19,Conclusions,4,20,4.conclusions,1、We demonstrated a facile route to synthesize highly ordered Pt/Pdbimetallic nano-tube electrodes based on an AAO template-directed electrochemical method.,2、The perpendicular Pt/Pd bimetallic nano-tubes presented in this manuscript are potentially useful as enhanced electro-catalysts in methanol or other types of fuel cell.,21,Thank you for your attention!,