A Research Of Noble Metal Catalyst Preparation And Electrocataly Performance In Direct Methanol Fuel Cell

Direct Methanol Fuel Cell（DMFC）is an energy source with high energy conversion efficiency,green and high security.Therefore,it has great application prospect in the field of large power and portable energy.Oxygen reduction reaction（ORR）occurred in the cathode and methanol oxidation reaction（MOR）in anode of the methanol fuel cell,However,ORR and MOR reaction kinetics are slowly.So we need some catalyst to quicken the reaction rate.At present,a large of platinum-based precious metal catalysts are used in methanol fuel cell.While the high cost and low stability limit its commercial development.So it is a great significance to preparation of high performance,low cost and high stability anode（methanol oxidation,MOR）and cathode catalyst（oxygen reduction,ORR）to accelerate its development.Due to noble metal has an irreplaceable position in the catalysis field,There fore,this paper mainly studies for the low-Pt noble metal catalysts and non-platinum noble metal catalyst.We prepare a small size catalyst with high performance and high stable,and study those electrocatalytic behavior to discover its kinetic process.Pt has good performance in electrocatalyst,while bad stability and easy to poison by Methanol.So adding some Au can improve its stability.First,we prepared different proportion of gold and platinum loading on multi-walled carbon nanotubes by one-pot method,Marked Au_4-x-x Pt_x/MWNTs（x=1,2,3）,those material has small size,through TEM test found that the mix nanoparticles size is about 3 nm,combined with XRD found between gold and platinum is not a simple mixture,but the formation of alloys.Electroche mical test indicated that when x=3（the ratio of Au and Pt is 1:3）,it shows the best ORR and MOR catalytic activity.Moreover,adding the Au increases the durability of the catalyst,and realise the less application of platinum.It is found that the cata lyst is a direct 4 electron process and has less intermediate products by rotating disk/ring electrode.Due to the high cost and little stock for Pt,research in the non-platinum catalyst is very hot.Such as the excellent stability of Au.One-pot method is used to prepare nanometer gold loading on multi-walled carbon nanotubes（Au/MWNTs）.We found that gold nanoparticles size is about 2.9 nm and there is minimal change after 3000 times cycle（3 nm）using transmission electron microscopy（TEM）,because of nanometer gold surface has been protected by ligand utilizing FT-IR and XPS analysis.electrochemical test found that this catalyst is a kind of high efficiency,high performance catalysts.No matter catalytic performance or durability are so much better than commercial 10%Pt/C,electrocatalytic performance is slightly lower than commercial 20%Pt/C,but its good resistance to methanol,excellent stably for a long time,make it becomes a good electrocatalytic material.The catalytic mechanism is the same as the commercial Pt/C catalyst,which is the direct four-electron process,by using the rotating disk electrode and the rotating disk electrode.Then continue to reduce costs and increase activity.We use one-pot method to prepare nano silver catalyst loading on multi-walled carbon nanotubes（Ag-MWNTs）,TEM found that the the catalyst has small size（3 nm）.We all known that silver is a much cheaper precious metal than Au and Pt,while it shows amazing electrocatalyst performance,which is similar to commercial 20%Pt/C by electrochemical testing.To study the influences between different loads and its catalytic performance.We prepared three different component Ag/MWNTs（17.8%,28.1%and 39.5%）.The study found the performance is the best when the load is28.1%,possibly due to the good synergistic effect of nano-silver and multi-walled carbon nanotubes under this loading.Using the rotating disk electrode and the rotating disk electrode,the process of the catalytic process was found to be a four-electron process that directly reacts to generate water.